EC-CDT-Unit-2; Corrosion and types of corrosion
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About This Presentation
Corrosion and types of corrosion
Slide Content
Dr.T.Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic-13
W4–L1-CDT13 Topic: Introduction to Corrosion
Corrosion by pure chemical reaction
(Dry corrosion)
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic-13
W4–L1-CDT13 Topic: Introduction to Corrosion
Corrosion by pure chemical reaction
(Dry corrosion)
Lecture Outcomes
(LOs)
After completion of this lecture, students will be able to…
LO1. discuss the chemical corrosion
LO2. select the physical conditions to preserve& protect
metals from dry corrosion.
U22CH103 Engineering Chemistry
2
(LOs)
After completion of this lecture, students will be able to…
LO1. discuss the chemical corrosion
LO2. select the physical conditions to preserve& protect
metals from dry corrosion.
U22CH103 Engineering Chemistry
2
CORROSION
Introduction: Corrosion has been defined as a destructive chemical and
electrochemical reaction of a metal with its environment (like O
2, moisture, CO
2
etc.) which disfigures metallic products leading to reduction in their thickness
and also causes loss of useful properties such as malleability, ductility, electrical
conductivity and optical refractivity.
Except few metals such as gold, platinum (called noble metal) are prone to
corrosion.
Typical examplesof corrosion
1.Rusting of iron due to formation of hydrated ferric oxide.
2.Tarnishing of silver wares in H
2S laden air due to formation of silver sulphide.
3
Introduction: Corrosion has been defined as a destructive chemical and
electrochemical reaction of a metal with its environment (like O
2, moisture, CO
2
etc.) which disfigures metallic products leading to reduction in their thickness
and also causes loss of useful properties such as malleability, ductility, electrical
conductivity and optical refractivity.
Except few metals such as gold, platinum (called noble metal) are prone to
corrosion.
Typical examplesof corrosion
1.Rusting of iron due to formation of hydrated ferric oxide.
2.Tarnishing of silver wares in H
2S laden air due to formation of silver sulphide.
3
CORROSION
Definition:
Any process of destruction and consequent loss of a solid
metallic material, through an unwanted chemical and
electrochemical attack by its environmental, starting at its
surface is called corrosion.
or
Disintegration of a metal by its surrounding chemicals
through a chemical or electrochemical reaction on the
surface of the metal is called corrosion.
Examples:
1.Formation of rust (Fe3O4 ) on the surface of iron
2.Formation of green film [CuCO3 + Cu(OH)2 ] on the surface
of coppe
Definition:
Any process of destruction and consequent loss of a solid
metallic material, through an unwanted chemical and
electrochemical attack by its environmental, starting at its
surface is called corrosion.
or
Disintegration of a metal by its surrounding chemicals
through a chemical or electrochemical reaction on the
surface of the metal is called corrosion.
Examples:
1.Formation of rust (Fe3O4 ) on the surface of iron
2.Formation of green film [CuCO3 + Cu(OH)2 ] on the surface
of coppe
CORROSION
U22CH103 Engineering Chemistry
W1-L1-CDT1 5
U22CH103 Engineering Chemistry
W1-L1-CDT1 5
CORROSION
6
6
Metals are electropositive in nature. Except few metals like gold,
platinum (noble metal) other metals are found in nature as their
compounds (such as oxides, hydroxides, carbonates, chlorides,
sulphides, phosphates, silicates etc.) which are called their ore.
Metals are thus obtained by extraction from their ores by reduction
process.
In nature, when metals exists as their compounds (or ore) they are
stable and they are in the low energy states.
7
platinum (noble metal) other metals are found in nature as their
compounds (such as oxides, hydroxides, carbonates, chlorides,
sulphides, phosphates, silicates etc.) which are called their ore.
Metals are thus obtained by extraction from their ores by reduction
process.
In nature, when metals exists as their compounds (or ore) they are
stable and they are in the low energy states.
7
However, during extraction of metals from their ores, free metals
become less stable and are in the higher energy state than in the ionic
state.
So, metals have a tendency to go back to the ionic state and hence metal
atoms are prone to get attacked by environment .
This is the main reason for corrosion of metals.
become less stable and are in the higher energy state than in the ionic
state.
So, metals have a tendency to go back to the ionic state and hence metal
atoms are prone to get attacked by environment .
This is the main reason for corrosion of metals.
R E F L E C T I O N S P O T - I
Define Corrosion
Answer:
Any process of destruction and consequent loss
of a solid metallic material, through an unwanted
chemical and electrochemical attack by its
environmental, stating at its surface is called
corrosion.
Define Corrosion
Answer:
Any process of destruction and consequent loss
of a solid metallic material, through an unwanted
chemical and electrochemical attack by its
environmental, stating at its surface is called
corrosion.
CORROSION
•Types Of Corrosion
⮚Dry or Chemical Corrosion
⮚Wet or Electrochemical
Corrosion
10
•Types Of Corrosion
⮚Dry or Chemical Corrosion
⮚Wet or Electrochemical
Corrosion
10
CORROSION
11
11
CORROSION
2M + n/2O
2 ) →
12
⮚Oxidation corrosion
⮚Occurs
⚫due to direct chemical reaction of atm. O2 with metal
surface forming metal oxide
⚫Absence of moisture
⚫Increases with increase in temp.
⮚Mechanism
⚫on exposure to atm., metal gets oxidized to form
metal ions
(i) M
+n
M (S) → + ne
-
⚫Electrons lost by metal are taken up by oxygen to
forms oxide ions
(ii)
1/2O
2 (g) + 2e
-
) → O
2-
2M
+n
+ nO
2- (
M2On
)
Metal oxide
2M + n/2O
2 ) →
12
⮚Oxidation corrosion
⮚Occurs
⚫due to direct chemical reaction of atm. O2 with metal
surface forming metal oxide
⚫Absence of moisture
⚫Increases with increase in temp.
⮚Mechanism
⚫on exposure to atm., metal gets oxidized to form
metal ions
(i) M
+n
M (S) → + ne
-
⚫Electrons lost by metal are taken up by oxygen to
forms oxide ions
(ii)
1/2O
2 (g) + 2e
-
) → O
2-
2M
+n
+ nO
2- (
M2On
)
Metal oxide
MECHANISM OF OXIDATION CORROSION
Rate of corrosion depends on the nature of the corrosion
produt
i.e metal oxide layer
•Nature of metal oxide layer
1.Unstable Layer :- Ag, Au, Pt
2.Stable Layer: - Al, Pb, Cu, Sn
3.Volatile Layer:- Mo
4.Porous Layer:- Alkali metals &alkaline earth metals
•
14
produt
i.e metal oxide layer
•Nature of metal oxide layer
1.Unstable Layer :- Ag, Au, Pt
2.Stable Layer: - Al, Pb, Cu, Sn
3.Volatile Layer:- Mo
4.Porous Layer:- Alkali metals &alkaline earth metals
•
14
CORROSION
15
15
CORROSION
16
16
⮚Pilling – Bedworth Rule
A protective and Non-Porous metal oxide layer has volume equal to
or greater than the volume of metal from which it is formed.
Protective layer: Volume of the oxide > Volume of the metal
NonProtective layer: Volume of the oxide <Volume of the metal
Specific Volume Ratio
A Non-Protective and Porous metal oxide layer has volume lesser than
the volume of metal from which it is formed.
Specific Volume Ratio = Volume of oxide formed
Volume of metal
A protective and Non-Porous metal oxide layer has volume equal to
or greater than the volume of metal from which it is formed.
Protective layer: Volume of the oxide > Volume of the metal
NonProtective layer: Volume of the oxide <Volume of the metal
Specific Volume Ratio
A Non-Protective and Porous metal oxide layer has volume lesser than
the volume of metal from which it is formed.
Specific Volume Ratio = Volume of oxide formed
Volume of metal
⮚Corrosion by Other Gases
• 2 Ag + Cl2 → 2 AgCl
(Non-Porous layer)
FeS + H2
•
• Fe + H2S →
Sn + 2Cl2 →
(Porous Layer)
SnCl4
(Volatile Layer)
⮚Liquid Metal Corrosion
•Occurs due to the action of flowing liquid metal at high temp on solid
metals or alloys.
•Observed in nuclear power plants where Na metal used as a
coolant leads to corrosion of Cd.
18
• 2 Ag + Cl2 → 2 AgCl
(Non-Porous layer)
FeS + H2
•
• Fe + H2S →
Sn + 2Cl2 →
(Porous Layer)
SnCl4
(Volatile Layer)
⮚Liquid Metal Corrosion
•Occurs due to the action of flowing liquid metal at high temp on solid
metals or alloys.
•Observed in nuclear power plants where Na metal used as a
coolant leads to corrosion of Cd.
18
Liquid Metal Corrosion
This is due to chemical action of flowing liquid
metal at high temperatures on solid metal or
alloy. Such corrosion occur in devices used for
nuclear power.
The corrosion reaction involves either:
(i)Dissolution of a solid metal by a liquid metal
or
(ii)Internal penetration of the liquid metal into
the solid metal.
This is due to chemical action of flowing liquid
metal at high temperatures on solid metal or
alloy. Such corrosion occur in devices used for
nuclear power.
The corrosion reaction involves either:
(i)Dissolution of a solid metal by a liquid metal
or
(ii)Internal penetration of the liquid metal into
the solid metal.
Define Pilling-Bedworth Rule.
Answer:
A protective and Non-Porous metal oxide layer hasvolume
equal to or greater than the volume of metal from which
it is formed.
Protective layer: Volume of the oxide > Volume of the metal
NonProtective layer: Volume of the oxide <Volume of the metal
R E F L E C T I O N S P O T - I I
Answer:
A protective and Non-Porous metal oxide layer hasvolume
equal to or greater than the volume of metal from which
it is formed.
Protective layer: Volume of the oxide > Volume of the metal
NonProtective layer: Volume of the oxide <Volume of the metal
R E F L E C T I O N S P O T - I I
SU MMA RY
Dry corrosion occurs mainly through the direct action of
atmospheric gases such as oxygen, halogen, hydrogen sulphide,
sulphur dioxide.
Dry corrosion is of following 3 types.
Oxidation corrosion occurs due to the direct action of
atmospheric oxygen. Extent of corrosion depends on the
nature of the corrosion product
Corrosion by other gases such as H
2S, Cl
2 .
Liquid metal Corrosion.
Dry corrosion occurs mainly through the direct action of
atmospheric gases such as oxygen, halogen, hydrogen sulphide,
sulphur dioxide.
Dry corrosion is of following 3 types.
Oxidation corrosion occurs due to the direct action of
atmospheric oxygen. Extent of corrosion depends on the
nature of the corrosion product
Corrosion by other gases such as H
2S, Cl
2 .
Liquid metal Corrosion.
LEC T U RE OU TC OM E REV I S I T ED
LO1. discuss the chemical corrosion
LO2. select the physical conditions to preserve& protect
metals from dry corrosion.
LO1. discuss the chemical corrosion
LO2. select the physical conditions to preserve& protect
metals from dry corrosion.
Lecture Level Problem (on LLO1):
1. Observe below given figure of mechanism of corrosion and solve the
following.
i)Identify the type of corrosion
ii)Give the corrosion reactions and over all corrosion reaction.
iii)Why corrosion product is always formed at nearer the surface of the metal.
iv)Which factor decides the corrosion of underlying metal? Explain.
1. Observe below given figure of mechanism of corrosion and solve the
following.
i)Identify the type of corrosion
ii)Give the corrosion reactions and over all corrosion reaction.
iii)Why corrosion product is always formed at nearer the surface of the metal.
iv)Which factor decides the corrosion of underlying metal? Explain.
FURTHER READING
Jain &Jain; Chapter 7
Topics:2
Thank you
Jain &Jain; Chapter 7
Topics:2
Thank you
Dr.T. Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
CLASSROOM DISCUSSION TOPIC-14
W4–L2-CDT14 TOPIC: ELECTRO CHEMICAL CORROSION
(WET CORROSION)
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
CLASSROOM DISCUSSION TOPIC-14
W4–L2-CDT14 TOPIC: ELECTRO CHEMICAL CORROSION
(WET CORROSION)
Lecture Outcomes (LOs)
After completion of this lecture, students will be able to…
LO1. distinguish electro chemical corrosion by hydrogen evolution
and by absorption of oxygen.
U22CH103 Engineering Chemistry
W1-L1-CDT1 2
After completion of this lecture, students will be able to…
LO1. distinguish electro chemical corrosion by hydrogen evolution
and by absorption of oxygen.
U22CH103 Engineering Chemistry
W1-L1-CDT1 2
It occurs when a metal is in contact with conducting liquid or when two dissimilar
metals are in contact with one another and either immersed or partially dipped in
conducting liquid.
Electrochemical corrosion involves:
i)The formation of anodic and cathodic areas or parts in contact with each other
ii)Presence of a conducting medium
iii)Corrosion occurs at anodic areas only
iv)Formation of corrosion product somewhere between anodic and cathodic areas.
This involves flow of electron-current between the anodic and cathodic areas.
WET OR ELECTROCHEMICAL CORROSION
metals are in contact with one another and either immersed or partially dipped in
conducting liquid.
Electrochemical corrosion involves:
i)The formation of anodic and cathodic areas or parts in contact with each other
ii)Presence of a conducting medium
iii)Corrosion occurs at anodic areas only
iv)Formation of corrosion product somewhere between anodic and cathodic areas.
This involves flow of electron-current between the anodic and cathodic areas.
WET OR ELECTROCHEMICAL CORROSION
Reactions of wet corrosion
At anodic area: oxidation reaction takes place (liberation of free electron), so
anodic metal is destroyed by either dissolving or assuming combined state
(such as oxide, etc.). Hence corrosion always occurs at anodic areas.
?????? �??????????????????� → ??????
�
+
�??????????????????� ??????�� + �??????
−
At cathodic area: Depends on the nature of the conducting liquid.
Cathodic reaction consumes electrons with either by (a) evolution of hydrogen or
(b) absorption of oxygen, depending on the nature of the corrosive environment.
At anodic area: oxidation reaction takes place (liberation of free electron), so
anodic metal is destroyed by either dissolving or assuming combined state
(such as oxide, etc.). Hence corrosion always occurs at anodic areas.
?????? �??????????????????� → ??????
�
+
�??????????????????� ??????�� + �??????
−
At cathodic area: Depends on the nature of the conducting liquid.
Cathodic reaction consumes electrons with either by (a) evolution of hydrogen or
(b) absorption of oxygen, depending on the nature of the corrosive environment.
(a) Evolution of Hydrogen Type:
It occurs in acidic environment.
All metals above hydrogen in the electrochemical
series have a tendency to get dissolved in acidic
solution with simultaneous evolution of hydrogen.
Consider the example of iron,
At anode: 2??????� → 2??????�
+2
+ 4�
−
These electrons flow through the metal, from anode to cathode, where H
+ ions of
acidic solution are eliminated as hydrogen gas.
The overall reaction is: 2??????� + 2??????2 + 4??????
+
→ 2??????�
+2
+ 2??????2??????
??????�
+2
��??????��� �??????�ℎ �??????��??????���� ??????2 �?????? �??????�� ����??????� ??????�??????�� (����)
At cathode:
+ −
2 ?????? + 2 � → ??????2
4 ??????
+
+ 4 �
−
+ ??????2 → 2??????2??????
It occurs in acidic environment.
All metals above hydrogen in the electrochemical
series have a tendency to get dissolved in acidic
solution with simultaneous evolution of hydrogen.
Consider the example of iron,
At anode: 2??????� → 2??????�
+2
+ 4�
−
These electrons flow through the metal, from anode to cathode, where H
+ ions of
acidic solution are eliminated as hydrogen gas.
The overall reaction is: 2??????� + 2??????2 + 4??????
+
→ 2??????�
+2
+ 2??????2??????
??????�
+2
��??????��� �??????�ℎ �??????��??????���� ??????2 �?????? �??????�� ����??????� ??????�??????�� (����)
At cathode:
+ −
2 ?????? + 2 � → ??????2
4 ??????
+
+ 4 �
−
+ ??????2 → 2??????2??????
(i) Evolution of Hydrogen Type
REFLECTION SPOT-I
Answer: a
Question:
Find the correct statement:
a.Corrosion always occurs at cathode
b.Corrosion always occur at anode
Answer: a
Question:
Find the correct statement:
a.Corrosion always occurs at cathode
b.Corrosion always occur at anode
Rusting of iron in neutral aqueous solution
of electrolytes (like NaCl solution) in the
presence of atmospheric oxygen is a
common example of this type of corrosion.
The surface of iron is usually coated with a
thin film of iron oxide.
However, if this iron oxide film develops some cracks, anodic areas are created on
the surface; while the well metal parts acts as cathodes.
(b) Absorption of Oxygen Type:
of electrolytes (like NaCl solution) in the
presence of atmospheric oxygen is a
common example of this type of corrosion.
The surface of iron is usually coated with a
thin film of iron oxide.
However, if this iron oxide film develops some cracks, anodic areas are created on
the surface; while the well metal parts acts as cathodes.
(b) Absorption of Oxygen Type:
(ii) If the supply of oxygen is limited, the corrosion product may be even black anhydrous
magnetite, Fe
3O
4.
At Anode: Metal dissolves as ferrous ions with
liberation of electrons. ??????� → ??????�
+2
+ 2�
−
At Cathode: The liberated electrons are
intercepted by the dissolved oxygen.
1
??????2 + ??????2?????? + 2�− → 2????????????
2
−
The Fe
2+ ions and OH
- ions diffuse and when they meet, ferrous hydroxide is precipitated.
????????????
??????
+
+ ??????????????????
−
→ ???????????? ????????????
??????
(i) If enough oxygen is present, ferrous hydroxide is easily oxidized to ferric hydroxide.
2 4??????� ???????????? + ??????2 + 2??????2?????? → 4??????� ???????????? 3 (??????���??????� ���� ??????�2??????3. ??????2??????
)
(b) Absorption of Oxygen Type:
magnetite, Fe
3O
4.
At Anode: Metal dissolves as ferrous ions with
liberation of electrons. ??????� → ??????�
+2
+ 2�
−
At Cathode: The liberated electrons are
intercepted by the dissolved oxygen.
1
??????2 + ??????2?????? + 2�− → 2????????????
2
−
The Fe
2+ ions and OH
- ions diffuse and when they meet, ferrous hydroxide is precipitated.
????????????
??????
+
+ ??????????????????
−
→ ???????????? ????????????
??????
(i) If enough oxygen is present, ferrous hydroxide is easily oxidized to ferric hydroxide.
2 4??????� ???????????? + ??????2 + 2??????2?????? → 4??????� ???????????? 3 (??????���??????� ���� ??????�2??????3. ??????2??????
)
(b) Absorption of Oxygen Type:
(ii) Absorption of Oxygen Type:
(ii) Absorption of Oxygen Type: Figure
Answer:
Diffusion rate of metal ion formed at anode is more than that of
negative ions formed at cathode
REFLECTION SPOT-II
Question:
Why corrosion product is always formed at a place nearer to
cathode?
Diffusion rate of metal ion formed at anode is more than that of
negative ions formed at cathode
REFLECTION SPOT-II
Question:
Why corrosion product is always formed at a place nearer to
cathode?
SUMMARY
Wet or electrochemical corrosion occurs due to the existence of separate anodic and
cathodic areas, between which current flows through the conducting solution.
At the anode: M
(s)M
n+
+ ne
-
At the cathode:
i)Hydrogen evolution
At anode: 2??????� → 2??????� +2 + 4� −
At cathode: ?????? + + 2 � − → ??????2 4 ?????? + + 4 � − + ??????2 → 2??????2??????
Net reaction: 2??????� + 2??????2 + 4?????? + → 2??????� +2 + 2??????2O
ii) absorption of oxygen depending upon the nature of corrosive environment.
At anode: ??????� → ??????� +2 + 2� −
At cathode: 1/2 ??????2 + ??????2?????? + 2�− → 2???????????? −
The Fe2+ ions and OH- ions diffuse and when they meet, ferrous hydroxide is precipitated.
?????????????????? + + ??????????????????− → ???????????? ???????????? ??????
If enough oxygen is present, ferrous hydroxide is easily oxidized to ferric hydroxide.
4??????� ???????????? 2 + ??????2 + 2??????2?????? → 4??????� ???????????? 3 (??????���??????� ���� ??????�2??????3. ??????2??????)
If the supply of oxygen is limited, the corrosion product may be even black anhydrous magnetite, Fe3O4 .
Wet or electrochemical corrosion occurs due to the existence of separate anodic and
cathodic areas, between which current flows through the conducting solution.
At the anode: M
(s)M
n+
+ ne
-
At the cathode:
i)Hydrogen evolution
At anode: 2??????� → 2??????� +2 + 4� −
At cathode: ?????? + + 2 � − → ??????2 4 ?????? + + 4 � − + ??????2 → 2??????2??????
Net reaction: 2??????� + 2??????2 + 4?????? + → 2??????� +2 + 2??????2O
ii) absorption of oxygen depending upon the nature of corrosive environment.
At anode: ??????� → ??????� +2 + 2� −
At cathode: 1/2 ??????2 + ??????2?????? + 2�− → 2???????????? −
The Fe2+ ions and OH- ions diffuse and when they meet, ferrous hydroxide is precipitated.
?????????????????? + + ??????????????????− → ???????????? ???????????? ??????
If enough oxygen is present, ferrous hydroxide is easily oxidized to ferric hydroxide.
4??????� ???????????? 2 + ??????2 + 2??????2?????? → 4??????� ???????????? 3 (??????���??????� ���� ??????�2??????3. ??????2??????)
If the supply of oxygen is limited, the corrosion product may be even black anhydrous magnetite, Fe3O4 .
LECTURE OUTCOME REVISITED
LO1. distinguish electro chemical corrosion by hydrogen
evolution and by absorption of oxygen.
LO1. distinguish electro chemical corrosion by hydrogen
evolution and by absorption of oxygen.
Lecture Level Problem (on LLO1):
1. Observe below given diagram and answer the following.
i)Identify the type of corrosion.
ii)Where corrosion product is formed?
iii)Write mechanism of the above type corrosion.
1. Observe below given diagram and answer the following.
i)Identify the type of corrosion.
ii)Where corrosion product is formed?
iii)Write mechanism of the above type corrosion.
FURTHER READING
Jain &Jain; Chapter 7
Topics:3
Thank you
Jain &Jain; Chapter 7
Topics:3
Thank you
Dr.T.Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic
W4–L3-CDT15 Topic: FACTORS INFLUENCING CORROSION
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic
W4–L3-CDT15 Topic: FACTORS INFLUENCING CORROSION
Lecture Outcomes (LOs)
After completion of this lecture, students will be able to…
LO1. list out the factors influencing corrosion
U22CH103 Engineering Chemistry
W1-L1-CDT1 2
After completion of this lecture, students will be able to…
LO1. list out the factors influencing corrosion
U22CH103 Engineering Chemistry
W1-L1-CDT1 2
There are two factors that influence the rate of corrosion. Hence a knowledge of
these factors and the mechanism with which they affect the corrosion rate is
essential because the rate of corrosion is different in different atmosphere.
1.Nature of the metal
2.Nature of the corroding environment
FACTORS INFLUENCING CORROSION
these factors and the mechanism with which they affect the corrosion rate is
essential because the rate of corrosion is different in different atmosphere.
1.Nature of the metal
2.Nature of the corroding environment
FACTORS INFLUENCING CORROSION
1) Nature of the metal:
a) Position in the galvanic series:
When two metals or alloy are in electrical
contact, in presence of an electrolyte, the
more active (or higher up in the series)
suffers corrosion.
The rate of severity of corrosion depends
on the difference in there position,
greater the difference faster the corrosion
of anodic metal.
Galvanic series have been prepared by studying the corrosion of metal and alloys in
a given environment like sea-water.
a) Position in the galvanic series:
When two metals or alloy are in electrical
contact, in presence of an electrolyte, the
more active (or higher up in the series)
suffers corrosion.
The rate of severity of corrosion depends
on the difference in there position,
greater the difference faster the corrosion
of anodic metal.
Galvanic series have been prepared by studying the corrosion of metal and alloys in
a given environment like sea-water.
b) Purity of metal: Impurities in a metal cause heterogeneity and form minute/tiny
electrochemical cells (at the exposed parts), and the anodic parts get corroded.
The cent percent pure metal will not undergo any type of corrosion.
For example, the rate of corrosion of aluminum in hydrochloric acid with increase
in the percentage impurity is noted.
c) Over voltage: The over voltage of a metal in a corrosive environment is inversely
proportional to corrosion rate.
For example, ???????????? rod placed in dilute ??????2????????????4, ??????2 is liberated with 0.74 ?????? over
voltage, ???????????? undergoes slow corrosion.
But when few drops of ????????????
+2
added to it, metallic copper deposited on ???????????? and acts
as cathode, with the result over voltage decreases to 0.33 ??????. Hence ???????????? undergo
rapid corrosion.
1) Nature of the metal:
electrochemical cells (at the exposed parts), and the anodic parts get corroded.
The cent percent pure metal will not undergo any type of corrosion.
For example, the rate of corrosion of aluminum in hydrochloric acid with increase
in the percentage impurity is noted.
c) Over voltage: The over voltage of a metal in a corrosive environment is inversely
proportional to corrosion rate.
For example, ???????????? rod placed in dilute ??????2????????????4, ??????2 is liberated with 0.74 ?????? over
voltage, ???????????? undergoes slow corrosion.
But when few drops of ????????????
+2
added to it, metallic copper deposited on ???????????? and acts
as cathode, with the result over voltage decreases to 0.33 ??????. Hence ???????????? undergo
rapid corrosion.
1) Nature of the metal:
d) Relative areas of the anodic and cathodic parts: When two dissimilar
metals or alloys are in contact, the corrosion of the anodic part is directly proportional
to the ratio of areas of the cathodic part and the anodic part.
Corrosion is more rapid and severe, and highly localized, if the anodic area is small
(e.g., a small steel pipe fitted in a large copper tank), because the current density
at a smaller anodic area is much greater and the demand for electrons can be met
by smaller anodic areas only by undergoing corrosion more risky.
e) Physical state of a metal: Less grain size of the metal, orientation of the
metallic crystal and stress influences corrosion
Less grain size causes more corrosion.
1) Nature of the metal:
metals or alloys are in contact, the corrosion of the anodic part is directly proportional
to the ratio of areas of the cathodic part and the anodic part.
Corrosion is more rapid and severe, and highly localized, if the anodic area is small
(e.g., a small steel pipe fitted in a large copper tank), because the current density
at a smaller anodic area is much greater and the demand for electrons can be met
by smaller anodic areas only by undergoing corrosion more risky.
e) Physical state of a metal: Less grain size of the metal, orientation of the
metallic crystal and stress influences corrosion
Less grain size causes more corrosion.
1) Nature of the metal:
2) Nature of the environment:
a)Temperature: The rate of corrosion is directly proportional to temperature i.e.,
rise in temperature increases the rate of corrosion. This is because the rate of
diffusion of ions increases with rise in temperature.
b)Moisture: The rate of corrosion will be more when the relative humidity of the
environment is high. The moisture acts as a solvent for oxygen, carbon
dioxide, sulphur dioxide etc. in the air to produce the electrolyte which is
required for setting up a corrosion cell.
c)Influence of pH: Generally acidic media (ie., pH<7) are more corrosive than
alkaline and neutral media.
Eg: Zn, which is rapidly corroded, even in weakly acidic solutions such as carbonic
acid suffers minimum corrosion at pH=11.
a)Temperature: The rate of corrosion is directly proportional to temperature i.e.,
rise in temperature increases the rate of corrosion. This is because the rate of
diffusion of ions increases with rise in temperature.
b)Moisture: The rate of corrosion will be more when the relative humidity of the
environment is high. The moisture acts as a solvent for oxygen, carbon
dioxide, sulphur dioxide etc. in the air to produce the electrolyte which is
required for setting up a corrosion cell.
c)Influence of pH: Generally acidic media (ie., pH<7) are more corrosive than
alkaline and neutral media.
Eg: Zn, which is rapidly corroded, even in weakly acidic solutions such as carbonic
acid suffers minimum corrosion at pH=11.
d)Presence of impurities in atmosphere: Atmosphere in industrial areas contains
corrosive gases like ????????????
2, ??????
2??????, ????????????
2 and fumes of ??????????????????, ??????
2????????????
4 etc. In presence of
these gases, the acidity of the liquid adjacent to the metal surfaces increases and
its electrical conductivity also increases, thereby the rate of corrosion increases.
e)Polarisation of electrodes: When certain substances added to corroding
environment corrosion is minimized, such substances are called as corrosion
inhibitors.
When inhibitor is added either anode becomes less anodic or cathode becomes
less cathodic with the resultant emf is decreased and corrosion is decreased.
2) Nature of the environment:
corrosive gases like ????????????
2, ??????
2??????, ????????????
2 and fumes of ??????????????????, ??????
2????????????
4 etc. In presence of
these gases, the acidity of the liquid adjacent to the metal surfaces increases and
its electrical conductivity also increases, thereby the rate of corrosion increases.
e)Polarisation of electrodes: When certain substances added to corroding
environment corrosion is minimized, such substances are called as corrosion
inhibitors.
When inhibitor is added either anode becomes less anodic or cathode becomes
less cathodic with the resultant emf is decreased and corrosion is decreased.
2) Nature of the environment:
Answer:
REFLECTION SPOT-I
Diffusion rate of metal ion formed at anode is increased with increasing of
temperature.
Question:
Why rate of corrosion increases with increasing of temperature?
REFLECTION SPOT-I
Diffusion rate of metal ion formed at anode is increased with increasing of
temperature.
Question:
Why rate of corrosion increases with increasing of temperature?
Answer: a
REFLECTION SPOT-II
Question:
In cathodic protection methods base metal forcedly
behaves as
a. Cathode
b. Anode
REFLECTION SPOT-II
Question:
In cathodic protection methods base metal forcedly
behaves as
a. Cathode
b. Anode
SUMMARY
Factors influencing corrosion
Nature of the metal and nature of the corroding environment influences
corrosion.
Hiher Position in the galvanic series, lowover voltage, less anodic area ,
impuririties in the metal, volatile,porous nature of the surface film, more
solubility of the corrosion products..etc favours corrosion.
High temperature, more humidity in the air, presence of impurities in
atmosphere, presence of suspended particles in atmosphere, low pH
etc..favours corrosion.
Factors influencing corrosion
Nature of the metal and nature of the corroding environment influences
corrosion.
Hiher Position in the galvanic series, lowover voltage, less anodic area ,
impuririties in the metal, volatile,porous nature of the surface film, more
solubility of the corrosion products..etc favours corrosion.
High temperature, more humidity in the air, presence of impurities in
atmosphere, presence of suspended particles in atmosphere, low pH
etc..favours corrosion.
LECTURE OUTCOME REVISITED
Having completed the discussion on factors influencing corrosion
LO1. list out the factors influencing corrosion
Having completed the discussion on factors influencing corrosion
LO1. list out the factors influencing corrosion
(a) Write the possible oxidation and reduction half reactions
that occur when magnesium is immersed in each of the
following solutions:
(i) HCl, (ii) an HCl solution containing dissolved oxygen, (iii)
an HCl solution containing dissolved oxygen and, in addition,
Fe2+ ions.
(iv) In which of these solutions would you expect the
magnesium to oxidize most rapidly? Why?
Lecture Level Problems ( LLO1):
that occur when magnesium is immersed in each of the
following solutions:
(i) HCl, (ii) an HCl solution containing dissolved oxygen, (iii)
an HCl solution containing dissolved oxygen and, in addition,
Fe2+ ions.
(iv) In which of these solutions would you expect the
magnesium to oxidize most rapidly? Why?
Lecture Level Problems ( LLO1):
FURTHER READING
Jain &Jain; Chapter 7
Topics:13
Thank you
Jain &Jain; Chapter 7
Topics:13
Thank you
Dr.T. Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic
W4– L4-CDT 16 TOPIC: CATHODIC PROTECTION
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic
W4– L4-CDT 16 TOPIC: CATHODIC PROTECTION
Lecture Outcomes (LOs)
After completion of this lecture, students will be able to…
LO1. explain prevention of corrosion by cathodic
protection.
2
After completion of this lecture, students will be able to…
LO1. explain prevention of corrosion by cathodic
protection.
2
b) Impressed current cathodic protection
1. Cathodic protection:
The principle involved in this method is to force the metal to be protected to behave
like a cathode.
Since there will not be any anodic area on the metal, corrosion does not occur.
to metallic There are two methods of applying cathodic protection
structures.
a)Sacrificial anodic protection (galvanic protection)
1. Cathodic protection:
The principle involved in this method is to force the metal to be protected to behave
like a cathode.
Since there will not be any anodic area on the metal, corrosion does not occur.
to metallic There are two methods of applying cathodic protection
structures.
a)Sacrificial anodic protection (galvanic protection)
a) Sacrificial anodic protection (galvanic protection)
Since Mg is a more active metal,
it is likely to lose electrons
??????
−
??????
−
The negative electrons are forced to flow from
anode structure to the structure protected
???????????? ???????????? ????????????????????????????????????????????????
Anode
Cathode
In this method, the metal structure can be protected from corrosion by connecting
it with wire to a more anodic metal.
As this more active metal is sacrificed in the process of saving metal from
corrosion, it is known as sacrificial anode.
The metals, commonly used as sacrificial anodes are Mg, Zn, Al and their alloys.
Soil
>
>
>
Since Mg is a more active metal,
it is likely to lose electrons
??????
−
??????
−
The negative electrons are forced to flow from
anode structure to the structure protected
???????????? ???????????? ????????????????????????????????????????????????
Anode
Cathode
In this method, the metal structure can be protected from corrosion by connecting
it with wire to a more anodic metal.
As this more active metal is sacrificed in the process of saving metal from
corrosion, it is known as sacrificial anode.
The metals, commonly used as sacrificial anodes are Mg, Zn, Al and their alloys.
Soil
>
>
>
Applications:
1.Protection of underground cables and pipelines from soil corrosion.
2.Protection of ships and boat hulls from marine corrosion.
3.Prevention of rusty water by inserting Mg sheets or rods into domestic water
boilers or tanks.
a) Sacrificial anodic protection (galvanic protection)
1.Protection of underground cables and pipelines from soil corrosion.
2.Protection of ships and boat hulls from marine corrosion.
3.Prevention of rusty water by inserting Mg sheets or rods into domestic water
boilers or tanks.
a) Sacrificial anodic protection (galvanic protection)
AN IMPRESSED CURRENT IS APPLIED TO
CONVERT THE CORRODING METAL FROM
ANODE TO CATHODE.
THE APPLIED CURRENT IS IN OPPOSITE
DIRECTION TO NULLIFY THE CORROSION
CURRENT.
THIS CAN BE ACCOMPLISHED BY APPLYING
CURRENT SOURCE LIKE BATTERY OR
RECTIFIER.
FINALLY, WILL BE CONNECTED TO THE
CORRODING METAL STRUCTURE WHICH IS TO
b) Impressed current cathodic protection
Inert
CONVERT THE CORRODING METAL FROM
ANODE TO CATHODE.
THE APPLIED CURRENT IS IN OPPOSITE
DIRECTION TO NULLIFY THE CORROSION
CURRENT.
THIS CAN BE ACCOMPLISHED BY APPLYING
CURRENT SOURCE LIKE BATTERY OR
RECTIFIER.
FINALLY, WILL BE CONNECTED TO THE
CORRODING METAL STRUCTURE WHICH IS TO
b) Impressed current cathodic protection
Inert
I
IMPRESSED CURRENT METHOD
IMPRESSED CURRENT METHOD
ADVANTAGES:
Operating and maintenance costs are less.
Suited for large structures and long term operations.
APPLICATIONS:
Tanks and pipelines, transmission line-towers, marine pipes, ships etc.
b) Impressed current cathodic protection
Operating and maintenance costs are less.
Suited for large structures and long term operations.
APPLICATIONS:
Tanks and pipelines, transmission line-towers, marine pipes, ships etc.
b) Impressed current cathodic protection
Answer: a
REFLECTION SPOT-I
Question:
In cathodic protection methods base metal forcedly
behaves as
a.Cathode
b.Anode
REFLECTION SPOT-I
Question:
In cathodic protection methods base metal forcedly
behaves as
a.Cathode
b.Anode
Question:
1.Name any one cathodic protection method.
Answer: sacrificial anode method
REFLECTION SPOT-II
Choose correct answer
1.Name any one cathodic protection method.
Answer: sacrificial anode method
REFLECTION SPOT-II
Choose correct answer
SUMMARY
•Cathodic Protection Methods: The principle involved in this method is
to force the metal to be protected to behave like a cathode
•In Sacrificial anodic protection method the base metallic structure is
connected by a wire to a more anodic metal, so that corrosion is
concentrated at this more active metal.
•In impressed current cathodic Protection,an impressed current is applied
in opposite direction to nullify the corrosion current, and convert the
corroding metal from anode to cathode
•Cathodic Protection Methods: The principle involved in this method is
to force the metal to be protected to behave like a cathode
•In Sacrificial anodic protection method the base metallic structure is
connected by a wire to a more anodic metal, so that corrosion is
concentrated at this more active metal.
•In impressed current cathodic Protection,an impressed current is applied
in opposite direction to nullify the corrosion current, and convert the
corroding metal from anode to cathode
LECTURE OUTCOME REVISITED
Having completed the discussion on Cathodic protection:
LO1. explain prevention of corrosion by cathodic protection
Having completed the discussion on Cathodic protection:
LO1. explain prevention of corrosion by cathodic protection
Lecture Level Problems (LLO1)
Observe below diagram and answer the following
(i) Identify the method of cathodic protection.
(ii) How Mg protects buried iron pipe line.
(iii) Give two examples for sacrificial anodes.
Observe below diagram and answer the following
(i) Identify the method of cathodic protection.
(ii) How Mg protects buried iron pipe line.
(iii) Give two examples for sacrificial anodes.
LLO2:
Observe the above diagram and answer the following
(i) Identify the method of cathodic protection.
(ii) Give the salient features of the process.
(iii) Give uses of above process.
Observe the above diagram and answer the following
(i) Identify the method of cathodic protection.
(ii) Give the salient features of the process.
(iii) Give uses of above process.
FURTHER READING
Jain &Jain; Chapter 7
Topics: 14
Thank you
Jain &Jain; Chapter 7
Topics: 14
Thank you
Dr.T.Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic
W4– L4-CDT 17 TOPIC: HOT DIPPING METHODS (GALVANISING AND TINNING)
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic
W4– L4-CDT 17 TOPIC: HOT DIPPING METHODS (GALVANISING AND TINNING)
Lecture Outcomes (LOs)
After completion of this lecture, students will be able to…
LO1. discuss Hot dipping methods(galvanising &
tinning) distinguish galvanising and tinning
LO2. distinguish galvanising and tinning
U22CH103 Engineering Chemistry
W1-L1-CDT1 2
After completion of this lecture, students will be able to…
LO1. discuss Hot dipping methods(galvanising &
tinning) distinguish galvanising and tinning
LO2. distinguish galvanising and tinning
U22CH103 Engineering Chemistry
W1-L1-CDT1 2
Figure:APPLICATION PROCESS OF ZINC COATING ON STEEL SHEET( GALVANIZING)
Figure: APPLICATION PROCESS OF ZINC COATING ON STEEL SHEET( GALVANIZING)
REFLECTION SPOT-I
Which Substance acts as flux in galvanizing?
a.Zinc chloride
b.Ammonium chloride
c.Ammonium hydroxide
d.None of the above
Answer: b
Which Substance acts as flux in galvanizing?
a.Zinc chloride
b.Ammonium chloride
c.Ammonium hydroxide
d.None of the above
Answer: b
Figure: APPLICATION PROCESS OF TINNING ON STEEL SHEET
Question:
1.How does tin protects base metal steel?
a. By its noble character
b. Sacrificial anode method
Answer: a
REFLECTION SPOT-II
Choose correct answer
1.How does tin protects base metal steel?
a. By its noble character
b. Sacrificial anode method
Answer: a
REFLECTION SPOT-II
Choose correct answer
S.n
o
Galvanizing Tinning
1 A process of covering iron or steel with a thin coat of
Zinc to protect from rusting
A process of covering steel with a thin coat of tin to
protect from corrosion
2 Zinc protects the iron sacrificially,since it is more
electropositive than iron and does not permit iron to
pass into the outside solution
tin protects the base metal,iron, from corrosion due to
its noble nature i.e less electropositive than iron and
higher corrosion resisstance
3 In galnized articles,zinc continues to protect the
underlying iron by galvanic cell action(i.e.,sacrificial
action),even if the coating of zinc is punctured or broken
at soime places
In tin-coated articles,tin is non-toxic and protects the
underlying iron till is the coating is perfect,Any break in
coating causes rapid corrosion of iron.
4 Galvanized containers cannot be used for storing acidic
foodstuff,since zinc reacts with food acids forming highly
toxic i.e., poisonous zinc compounds
Tin coated containers and utensils can be used for
storing any food stuff,since tin is non-toxic and protects
the metal from corrosion and avoids any food
poisoning.
GALVANIZING VERSUS TINNING
o
Galvanizing Tinning
1 A process of covering iron or steel with a thin coat of
Zinc to protect from rusting
A process of covering steel with a thin coat of tin to
protect from corrosion
2 Zinc protects the iron sacrificially,since it is more
electropositive than iron and does not permit iron to
pass into the outside solution
tin protects the base metal,iron, from corrosion due to
its noble nature i.e less electropositive than iron and
higher corrosion resisstance
3 In galnized articles,zinc continues to protect the
underlying iron by galvanic cell action(i.e.,sacrificial
action),even if the coating of zinc is punctured or broken
at soime places
In tin-coated articles,tin is non-toxic and protects the
underlying iron till is the coating is perfect,Any break in
coating causes rapid corrosion of iron.
4 Galvanized containers cannot be used for storing acidic
foodstuff,since zinc reacts with food acids forming highly
toxic i.e., poisonous zinc compounds
Tin coated containers and utensils can be used for
storing any food stuff,since tin is non-toxic and protects
the metal from corrosion and avoids any food
poisoning.
GALVANIZING VERSUS TINNING
SUMMARY
•Galvanizing: It involves application of Zn coating is
over steel
•Zn is more anodic than Iron
•Zn coating protects Iron by sacrificial anodic method
•Tinnig: It involves application of tin coating over steel
•Tin is more cathodic than Iron
•Tin coating protects Iron by its noble character
•Galvanizing: It involves application of Zn coating is
over steel
•Zn is more anodic than Iron
•Zn coating protects Iron by sacrificial anodic method
•Tinnig: It involves application of tin coating over steel
•Tin is more cathodic than Iron
•Tin coating protects Iron by its noble character
LECTURE OUTCOME REVISITED
Having completed the discussion on Introduction to Corrosion
Corrosion by pure chemical reaction(Dry corrosion)
LO1. discuss Hot dipping methods(galvanising & tinning)
LO2. distinguish galvanising and tinning
Having completed the discussion on Introduction to Corrosion
Corrosion by pure chemical reaction(Dry corrosion)
LO1. discuss Hot dipping methods(galvanising & tinning)
LO2. distinguish galvanising and tinning
Lecture Level Problems ( LLO1):
1. Observe below given figure and solve the following.
i. Identify the name of the process of application of coating on a base metal.
i. Mention the role of dil. H
2SO
4
ii. Give the role of flux ammonium chloride.
iii. How zinc coating protects Iron sheet from corrosion?
1. Observe below given figure and solve the following.
i. Identify the name of the process of application of coating on a base metal.
i. Mention the role of dil. H
2SO
4
ii. Give the role of flux ammonium chloride.
iii. How zinc coating protects Iron sheet from corrosion?
Lecture Level Problems ( LLO2):
1.Observe the below diagram and answer the following.
i)Identify the name of the process.
ii)Give the role of zinc chloride flux.
iii)Mention the role of palm oil.
iv)How does tin coating protects Iron sheet from corrosion? What happens if a crack/pore is
formed on the coating?
1.Observe the below diagram and answer the following.
i)Identify the name of the process.
ii)Give the role of zinc chloride flux.
iii)Mention the role of palm oil.
iv)How does tin coating protects Iron sheet from corrosion? What happens if a crack/pore is
formed on the coating?
FURTHER READING
Jain &Jain; Chapter 7
Topics: 7
Thank you
Jain &Jain; Chapter 7
Topics: 7
Thank you
Dr.T. Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic
W5– L2-CDT18 TOPIC:Metal cladding and electroplating.
Department of Physical Sciences
Kakatiya Institute of Technology and Science,
Warangal, TS, India-506015
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic
W5– L2-CDT18 TOPIC:Metal cladding and electroplating.
Lecture Outcomes (LOs)
After completion of this lecture, students will be able to…
LO1. discuss metal cladding and electroplating
LO2:distinguish metal cladding and Electro
plating(electro deposition)
U22CH103 Engineering Chemistry
W1-L1-CDT1 2
After completion of this lecture, students will be able to…
LO1. discuss metal cladding and electroplating
LO2:distinguish metal cladding and Electro
plating(electro deposition)
U22CH103 Engineering Chemistry
W1-L1-CDT1 2
Metal cladding:
•It is the Process of by which a dense homogeneous layer of coating metal is
bonded firmly and permanently to the base metal on one or both sides.
•Generally cladding is accomplished by arranging thin sheets of coating metal
and the base metal sheet in the form of a sandwich which are then passed
through rollers under the action of heat and pressure.
•Eg: Alclad Sheet, In which duralumin is coated with aluminum. Plate of
duralumin is sandwiched between two layers of 99.5% pure Al. In air craft
industry Alclad sheeting is used.
Figure: Metal cladding
•It is the Process of by which a dense homogeneous layer of coating metal is
bonded firmly and permanently to the base metal on one or both sides.
•Generally cladding is accomplished by arranging thin sheets of coating metal
and the base metal sheet in the form of a sandwich which are then passed
through rollers under the action of heat and pressure.
•Eg: Alclad Sheet, In which duralumin is coated with aluminum. Plate of
duralumin is sandwiched between two layers of 99.5% pure Al. In air craft
industry Alclad sheeting is used.
Figure: Metal cladding
•The choice of cladding material depends on on the
corrosion-resistance required for any particular
environment.
•All corrosion resisting metals like
nickel,copper,lead,silver,platinum,Aluminium..etc can be
used as cladding materials
• alloys like stainless steel, nickel alloys, copper alloys, lead
alloys,etc can be used as cladding materials
Cladding materials
corrosion-resistance required for any particular
environment.
•All corrosion resisting metals like
nickel,copper,lead,silver,platinum,Aluminium..etc can be
used as cladding materials
• alloys like stainless steel, nickel alloys, copper alloys, lead
alloys,etc can be used as cladding materials
Cladding materials
REFLECTION SPOT-I
Choose the correct answer:
Question: In Alclad sheet Duralumin is sandwiched by……..
a.Magnesium
b.Aluminium
c.Copper
d.Platinum
Answer: b
Choose the correct answer:
Question: In Alclad sheet Duralumin is sandwiched by……..
a.Magnesium
b.Aluminium
c.Copper
d.Platinum
Answer: b
Electroplating: It is the process by which the coating
metal is deposited on the base metal by passing direct
electric current through an electrolytic solution containing
the soluble salt of the coating metal.
metal is deposited on the base metal by passing direct
electric current through an electrolytic solution containing
the soluble salt of the coating metal.
ELECTROPLATING
(ii) Electroplating
•Low temperature
•High current density
•Low metal ion concentration
Electroplating is the electro-deposition of metal,
by means electrolysis over surface of metals,
alloys or non-metals.
The article to be plated is cleaned with organic
solvents.
Treated with dil. HCl/H
2SO
4.
Then made cathode of electrolytic cell.
The anode is either the coating metal or
an electrode of inert material like graphite.
Under the influence of electric current,
coating metal ions migrate to the cathode
and gets deposited.
FAVOURABLE CONDITIONS
•Low temperature
•High current density
•Low metal ion concentration
Electroplating is the electro-deposition of metal,
by means electrolysis over surface of metals,
alloys or non-metals.
The article to be plated is cleaned with organic
solvents.
Treated with dil. HCl/H
2SO
4.
Then made cathode of electrolytic cell.
The anode is either the coating metal or
an electrode of inert material like graphite.
Under the influence of electric current,
coating metal ions migrate to the cathode
and gets deposited.
FAVOURABLE CONDITIONS
OBJECTIVES OF ELECTROPLATING
1.ON METALS:
•to increase the resistance to corrosion of the plated metal
• to increase resistance to chemical attack and wear resistance
•To improve physical appearance and surface hardness
•To improve the surface properties
•To improve decorative and commercial values of the metal
2.ON NON-METALS
•For increasing strength
•For preservation and decoration of the surface of non-metallic
materials like wood ,glass and plastics
•For making the surface conductivity by utilization of light-weight
non-metallic materials like wood and plastics
1.ON METALS:
•to increase the resistance to corrosion of the plated metal
• to increase resistance to chemical attack and wear resistance
•To improve physical appearance and surface hardness
•To improve the surface properties
•To improve decorative and commercial values of the metal
2.ON NON-METALS
•For increasing strength
•For preservation and decoration of the surface of non-metallic
materials like wood ,glass and plastics
•For making the surface conductivity by utilization of light-weight
non-metallic materials like wood and plastics
Question: In electroplating process base metal acts as
a. cathode
b. Anode
c. None of the above
Answer: a
REFLECTION SPOT-II
Choose the correct answer
a. cathode
b. Anode
c. None of the above
Answer: a
REFLECTION SPOT-II
Choose the correct answer
SUMMARY
Metal cladding: It is the Process of by which a dense homogeneous layer of
coating metal is bonded firmly and permanently to the base metal on one or both
sides.
Generally cladding is accomplished by arranging thin sheets of coating metal and
the base metal sheet in the form of a sandwich which are then passed through
rollers under the action of heat and pressure.
Example: Alclad Sheet, In which duralumin is coated with aluminum.
Electroplating: it is the process by which the coating metal is deposited on the
base metal by passing direct electric current through an electrolytic solution
containing the soluble salt of the coating metal.
Metal cladding: It is the Process of by which a dense homogeneous layer of
coating metal is bonded firmly and permanently to the base metal on one or both
sides.
Generally cladding is accomplished by arranging thin sheets of coating metal and
the base metal sheet in the form of a sandwich which are then passed through
rollers under the action of heat and pressure.
Example: Alclad Sheet, In which duralumin is coated with aluminum.
Electroplating: it is the process by which the coating metal is deposited on the
base metal by passing direct electric current through an electrolytic solution
containing the soluble salt of the coating metal.
LECTURE OUTCOME REVISITED
Having completed the discussion on Metal cladding and electroplating
LO1.discuss metal cladding and electroplating
LO2.distinguish metal cladding and Electro
plating(electro deposition)
Having completed the discussion on Metal cladding and electroplating
LO1.discuss metal cladding and electroplating
LO2.distinguish metal cladding and Electro
plating(electro deposition)
Lecture Level Problems ( LLO1):
Observe the below diagram and the following.
i)Identify the process of prevention method of corrosion.
ii)Write the process of application aluminium coating on
duralumin.
iii)Give the superior characters of alclad sheet compared to
duralumin.
Observe the below diagram and the following.
i)Identify the process of prevention method of corrosion.
ii)Write the process of application aluminium coating on
duralumin.
iii)Give the superior characters of alclad sheet compared to
duralumin.
FURTHER READING
Jain &Jain:
metal claddingChapter 7,Topic: 7
Electroplating:Chapter 8,Topic 3
Thank you
Jain &Jain:
metal claddingChapter 7,Topic: 7
Electroplating:Chapter 8,Topic 3
Thank you
Dr.T.Madhukar Reddy
Associate Professor
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic-19
W1 – L4-CDT-19
Topic:Phase rule :
Description of the terms:
‘Phase’, ‘Component’ and ‘Degrees of freedom’, Gibbs Phase rule equation.
Associate Professor
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic-19
W1 – L4-CDT-19
Topic:Phase rule :
Description of the terms:
‘Phase’, ‘Component’ and ‘Degrees of freedom’, Gibbs Phase rule equation.
Lecture Outcome (LO)
After completion of this lecture, students will be able
to…
LO1. explain terms ‘phase’, ‘component’
and ‘degrees of freedom’& Gibbs Phase rule equation
After completion of this lecture, students will be able
to…
LO1. explain terms ‘phase’, ‘component’
and ‘degrees of freedom’& Gibbs Phase rule equation
The phase rule describes the possible number of degrees
of freedom in an enclosed system at equilibrium, in terms
of the number of separate phases and the number of
chemical constituents in the system. It was deduced by
J.Williard Gibbs in 1875
PHASE RULE
of freedom in an enclosed system at equilibrium, in terms
of the number of separate phases and the number of
chemical constituents in the system. It was deduced by
J.Williard Gibbs in 1875
PHASE RULE
Phase rule
It states that when the equillibrium between any number of phases is
influenced only by temperature, pressure and concentration but not
influenced by gravity, or elctrical or magnetic forces or by surface action
then the number of degrees of freedom (F) of the system is related to
the number of components (C) and of phases (P) by the phase rule
equation
F = C – P + 2 (or) ?????? + ?????? = ?????? + ??????
It states that when the equillibrium between any number of phases is
influenced only by temperature, pressure and concentration but not
influenced by gravity, or elctrical or magnetic forces or by surface action
then the number of degrees of freedom (F) of the system is related to
the number of components (C) and of phases (P) by the phase rule
equation
F = C – P + 2 (or) ?????? + ?????? = ?????? + ??????
PHASE RULE
U22CH103 Engineering Chemistry
W1-L1-CDT1 5
U22CH103 Engineering Chemistry
W1-L1-CDT1 5
U22CH103 Engineering Chemistry W1-L1-CDT1 6
PHASE RULE
U22CH103 Engineering Chemistry W1-L1-CDT1 7
U22CH103 Engineering Chemistry W1-L1-CDT1 7
U22CH103 Engineering Chemistry W1-L1-CDT1 8
Phase Rule-Description of the terms
MgCO3 (s) ↔ MgO (s) + CO2 (g) P=3
(P) :
Phase Rule-Description of the terms
MgCO3 (s) ↔ MgO (s) + CO2 (g) P=3
(P) :
PHASE RULE
U22CH103 Engineering Chemistry W1-L1-CDT1 9
U22CH103 Engineering Chemistry W1-L1-CDT1 9
Contd….
Component:
The term component is defined as the least number of independent chemical
constituents in terms of which the composition of every phase can be
expressed by means of a chemical equation.
For a physical change,
No. of components C = no. of chemical species
Example:
���� ������ �����??????��; � = 2 (����� + ����)
�??????����� �� �����, ??????��, ����; � = 3 (�� �ℎ��??????��� �����??????�� ������)
For a chemical change,
No. of components C = no. of chemical species-no. of chemical equations
Example:
1. ����3 � ⇋ ���(�) + ��2(�)
� = 3 − 1
� = 2
Component:
The term component is defined as the least number of independent chemical
constituents in terms of which the composition of every phase can be
expressed by means of a chemical equation.
For a physical change,
No. of components C = no. of chemical species
Example:
���� ������ �����??????��; � = 2 (����� + ����)
�??????����� �� �����, ??????��, ����; � = 3 (�� �ℎ��??????��� �����??????�� ������)
For a chemical change,
No. of components C = no. of chemical species-no. of chemical equations
Example:
1. ����3 � ⇋ ���(�) + ��2(�)
� = 3 − 1
� = 2
��� ⇋ ����� ⇋ ������
� = 1
��4�� � ⇋ ��3 � + ��� (�) (������ ������)
(??????) �� ���3
= ����
� = 3 − 2
� = 1
???????????? ??????ℎ�� ���� ������ �� ��3 �� ��� ??????� ??????��������� �� ������
� �ℎ��, ���3
≠ ����
� = 3 − 1
� = 2
?????? ��������� �����??????�� �� ���� ??????� ������� �??????�ℎ ������ ���??????� ���� ℎ�� ��� �ℎ����.
� = 1
��4�� � ⇋ ��3 � + ��� (�) (������ ������)
(??????) �� ���3
= ����
� = 3 − 2
� = 1
???????????? ??????ℎ�� ���� ������ �� ��3 �� ��� ??????� ??????��������� �� ������
� �ℎ��, ���3
≠ ����
� = 3 − 1
� = 2
?????? ��������� �����??????�� �� ���� ??????� ������� �??????�ℎ ������ ���??????� ���� ℎ�� ��� �ℎ����.
Answer: a
REFLECTION SPOT-I
Calculate the no. of phases present in the following system
MgCO3 (s) ↔ MgO (s) + CO2 (g)
a. P = 3
b. P = 2
c. P= 2
d. P = 3
REFLECTION SPOT-I
Calculate the no. of phases present in the following system
MgCO3 (s) ↔ MgO (s) + CO2 (g)
a. P = 3
b. P = 2
c. P= 2
d. P = 3
PHASE RULE
U22CH103 Engineering Chemistry W1-L1-CDT1 13
U22CH103 Engineering Chemistry W1-L1-CDT1 13
The no. of variables that must be defined to determine the state of a
system
The phase rule equation is
?????? = ?????? − ?????? + ??????
Where
?????? = ������ �� �������
(No. of variables to define a system)
� = ������ �� �ℎ����
� = ������ �� ����������
�� ���??????�??????��??????�� ��� � ������ �� ��� ������??????�??????��
Phase Rule
system
The phase rule equation is
?????? = ?????? − ?????? + ??????
Where
?????? = ������ �� �������
(No. of variables to define a system)
� = ������ �� �ℎ����
� = ������ �� ����������
�� ���??????�??????��??????�� ��� � ������ �� ��� ������??????�??????��
Phase Rule
??????���� �??????��??????�
�ℎ���� (�) = 1
���������� (�) = 1
??????���� �??????��??????� ⇋ Water ������
� = 2
� = 1
•����� �����??????�� (���������)
•� = 1
•� = 2 (??????���� + �����)
•??????���� + ����� �����??????�� (����� ���������)
•� = 2
•� = 2 (??????���� + �����)
The Gibbs Phase Rule: ?????? = ?????? − ?????? + ??????
�ℎ���� (�) = 1
���������� (�) = 1
??????���� �??????��??????� ⇋ Water ������
� = 2
� = 1
•����� �����??????�� (���������)
•� = 1
•� = 2 (??????���� + �����)
•??????���� + ����� �����??????�� (����� ���������)
•� = 2
•� = 2 (??????���� + �����)
The Gibbs Phase Rule: ?????? = ?????? − ?????? + ??????
Answer: a
REFLECTION SPOT-Ii
Degree of freedom means
a. Minimum number of variables required to define a system
b. Maximum number of variables required to define a system
REFLECTION SPOT-Ii
Degree of freedom means
a. Minimum number of variables required to define a system
b. Maximum number of variables required to define a system
SUMMARY
Phase (P) : An homogeneneous physically distinct and
mechanically separable portion of system, which is separated
from other such parts of the system by definite boundary
surfaces.
Component (C):The smallest number of independent variable
constituents, taking part in the state of equilibrium, by means
the composition of each phase can be expressed in the form of
chemical equation.
Degree of freedom(D):The minimum number of independently
variable factors, such as temperature, pressure and
composition of the phases, which must be arbitrarily specified
in order to represent perfectly the condition of a system.
Phase rule equation: F=C-P+2
Phase (P) : An homogeneneous physically distinct and
mechanically separable portion of system, which is separated
from other such parts of the system by definite boundary
surfaces.
Component (C):The smallest number of independent variable
constituents, taking part in the state of equilibrium, by means
the composition of each phase can be expressed in the form of
chemical equation.
Degree of freedom(D):The minimum number of independently
variable factors, such as temperature, pressure and
composition of the phases, which must be arbitrarily specified
in order to represent perfectly the condition of a system.
Phase rule equation: F=C-P+2
LECTURE OUTCOME REVISITED
LO1. explain terms ‘phase’, ‘component’
and ‘degrees of freedom’& Gibbs Phase rule
equation
Having completed the discussion on
Phase rule :
Description of the terms:
‘Phase’, ‘Component’ and ‘Degrees of freedom’, Gibbs Phase rule
equation
LO1. explain terms ‘phase’, ‘component’
and ‘degrees of freedom’& Gibbs Phase rule
equation
Having completed the discussion on
Phase rule :
Description of the terms:
‘Phase’, ‘Component’ and ‘Degrees of freedom’, Gibbs Phase rule
equation
Lecture Level practice Problems (LLPs)
LLP1:State Gibb’s Phase rule .Explain the terms involved in it by giving
two illustrative examples each
LLP2:What is the number of phases in the following systems?
I. Saturated solution of NaCl
ii. Mixture of Rhombic,monoclinic sulphur
iii. Decomposition equilibrium of CaCO3
LLP1:State Gibb’s Phase rule .Explain the terms involved in it by giving
two illustrative examples each
LLP2:What is the number of phases in the following systems?
I. Saturated solution of NaCl
ii. Mixture of Rhombic,monoclinic sulphur
iii. Decomposition equilibrium of CaCO3
FURTHER READING
Jain &Jain; Chapter 6 Topics: 09
Problems:
Jain &Jain; (pg.391),Topic:1
TUTORIAL NOTES
Jain &Jain; Chapter 6 Topics: 09
Problems:
Jain &Jain; (pg.391),Topic:1
TUTORIAL NOTES
Dr.T.Madhukar Reddy
Associate Professor
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic-20
W1 – L4-CDT-20
Topic:Application of phase rule to one component system
(water system)
Associate Professor
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic-20
W1 – L4-CDT-20
Topic:Application of phase rule to one component system
(water system)
Lecture Outcome (LO)
After completion of this lecture, students will be able
to…
LO1. explain one component system(Water System)
After completion of this lecture, students will be able
to…
LO1. explain one component system(Water System)
Application of Phase rule to one component system (Water system):
H
2O is single or one component system C = 1
F = C-P+2
F=1-P+2
F = 3-P
In this system possible phases are i) Ice, ii) Water, iii) Vapour
These three phases can co exist four possible combinations
H
2O is single or one component system C = 1
F = C-P+2
F=1-P+2
F = 3-P
In this system possible phases are i) Ice, ii) Water, iii) Vapour
These three phases can co exist four possible combinations
The degree of freedom depends on the number of phases
present on equilibrium
F = 3-P
i) P = 1, F = 2 (bi variant system)
ii) P = 2, F = 1 (uni variant system)
iii) P = 3, F = 0 (in variant system)
Any one component system the maximum number of degree of freedom is two.
The most convenient variables are pressure and temperature
present on equilibrium
F = 3-P
i) P = 1, F = 2 (bi variant system)
ii) P = 2, F = 1 (uni variant system)
iii) P = 3, F = 0 (in variant system)
Any one component system the maximum number of degree of freedom is two.
The most convenient variables are pressure and temperature
One component (water) system
5
According to phase rule F=C-P+2 it is clear that when there is one
component in the system existing in one phase(p=1), then the degrees of
freedom(F) calculated from phase rule comes out as 2.
Hence all the system, of one component can be completely described on
paper by taking two variable factors i.e., pressure and temperature
Ice water vapour
The number of phases that can exist in equilibrium at any time depends upon
the condition of pressure and temperature. The phase diagram has following
parts.
1)The curves OA,OB and OC (solid lines)
2) Three areas AOC,BOC and AOB.
3)Triple point ’O’
4)One meta stale curve OA’(dotted lines)
5
According to phase rule F=C-P+2 it is clear that when there is one
component in the system existing in one phase(p=1), then the degrees of
freedom(F) calculated from phase rule comes out as 2.
Hence all the system, of one component can be completely described on
paper by taking two variable factors i.e., pressure and temperature
Ice water vapour
The number of phases that can exist in equilibrium at any time depends upon
the condition of pressure and temperature. The phase diagram has following
parts.
1)The curves OA,OB and OC (solid lines)
2) Three areas AOC,BOC and AOB.
3)Triple point ’O’
4)One meta stale curve OA’(dotted lines)
One component system
Areas:
��� − ????????????��??????� �ℎ??????��
��� − ????????????���� �ℎ??????��
��� − ??????�????????????� �ℎ??????��
Curves/lines:
�� − ????????????��??????� ⇋ �??????����
�� − ��????????????� (??????��) ⇋ �??????����
�� − ��????????????� (??????��) ⇋ �??????����
Triple point (O):
��????????????� (??????��) ⇋ ????????????��??????� ⇋ �??????����
Curve OB’:
Metastable equilibrium
??????���� − ���?????? ⇋ �??????��� ????????????����
��??????����: ????????????��� ������
� = 1
� = � − � + ??????
� = 1 − 1 + ??????
� = ??????
Areas:
��� − ????????????��??????� �ℎ??????��
��� − ????????????���� �ℎ??????��
��� − ??????�????????????� �ℎ??????��
Curves/lines:
�� − ????????????��??????� ⇋ �??????����
�� − ��????????????� (??????��) ⇋ �??????����
�� − ��????????????� (??????��) ⇋ �??????����
Triple point (O):
��????????????� (??????��) ⇋ ????????????��??????� ⇋ �??????����
Curve OB’:
Metastable equilibrium
??????���� − ���?????? ⇋ �??????��� ????????????����
��??????����: ????????????��� ������
� = 1
� = � − � + ??????
� = 1 − 1 + ??????
� = ??????
���??????�
: �??????� − �??????��??????� �??????��� ��??????���
��. �� �ℎ??????��� = 1
?????? = � − � + 2
?????? = 1 − 1 + 2
?????? = 2 (�??????�??????�??????���)
�??????� − ���??????� (??????��) ��??????���
��. �� �ℎ??????��� = 1
?????? = � − � + 2
?????? = 1 − 1 + 2
?????? = 2 (�??????�??????�??????���)
�??????� − �??????��� �??????���� ��??????���
��. �� �ℎ??????��� = 1
?????? = � − � + 2
?????? = 1 − 1 + 2
?????? = 2 (�??????�??????�??????���)
It means to define these areas two variables pressure and temperature are required.
: �??????� − �??????��??????� �??????��� ��??????���
��. �� �ℎ??????��� = 1
?????? = � − � + 2
?????? = 1 − 1 + 2
?????? = 2 (�??????�??????�??????���)
�??????� − ���??????� (??????��) ��??????���
��. �� �ℎ??????��� = 1
?????? = � − � + 2
?????? = 1 − 1 + 2
?????? = 2 (�??????�??????�??????���)
�??????� − �??????��� �??????���� ��??????���
��. �� �ℎ??????��� = 1
?????? = � − � + 2
?????? = 1 − 1 + 2
?????? = 2 (�??????�??????�??????���)
It means to define these areas two variables pressure and temperature are required.
Curves:
AO-�??????��??????� ⇋ �??????����
��. �� �ℎ??????��� = 2
?????? = � − � + 2
?????? = 1 − 2 + 2
?????? = 1 (��??????�??????�????????????��)
BO-���??????� ??????�� ⇋ �??????����
��. �� �ℎ??????��� = 2
?????? = � − � + 2
?????? = 1 − 2 + 2
?????? = 1 (��??????�??????�????????????��)
CO-���??????� (??????��) ⇋ �??????����
��. �� �ℎ??????��� = 2
?????? = � − � + 2
?????? = 1 − 2 + 2
?????? = 1 (��??????�??????�????????????��)
AO curve will extend up to the critical temperature ( 374
oC). Beyond the critical temperature
the equilibrium will disappear only water vapour will exist.
AO-�??????��??????� ⇋ �??????����
��. �� �ℎ??????��� = 2
?????? = � − � + 2
?????? = 1 − 2 + 2
?????? = 1 (��??????�??????�????????????��)
BO-���??????� ??????�� ⇋ �??????����
��. �� �ℎ??????��� = 2
?????? = � − � + 2
?????? = 1 − 2 + 2
?????? = 1 (��??????�??????�????????????��)
CO-���??????� (??????��) ⇋ �??????����
��. �� �ℎ??????��� = 2
?????? = � − � + 2
?????? = 1 − 2 + 2
?????? = 1 (��??????�??????�????????????��)
AO curve will extend up to the critical temperature ( 374
oC). Beyond the critical temperature
the equilibrium will disappear only water vapour will exist.
Triple point (Point ‘O’)
At triple point all the three phases namely ice, water and vapour coexist.
��????????????� (??????��) ⇋ ????????????��??????� ⇋ �??????����
��. �� �ℎ??????��� = 3
?????? = � − � + 2
?????? = 1 − 3 + 2
?????? = 0 (��� �??????�????????????��)
At this triple point, neither pressure nor temperature
can be altered even slightly without causing the
disappearance of one of the phases.
It means that three phases can coexist in
equilibrium only at a definite temperature and
pressure. The values are 0.0075
o
C and 4.58
mm respectively.
At triple point all the three phases namely ice, water and vapour coexist.
��????????????� (??????��) ⇋ ????????????��??????� ⇋ �??????����
��. �� �ℎ??????��� = 3
?????? = � − � + 2
?????? = 1 − 3 + 2
?????? = 0 (��� �??????�????????????��)
At this triple point, neither pressure nor temperature
can be altered even slightly without causing the
disappearance of one of the phases.
It means that three phases can coexist in
equilibrium only at a definite temperature and
pressure. The values are 0.0075
o
C and 4.58
mm respectively.
Phase diagram of water system
REFLECTION SPOT-I
Which of the following system is example for one component system
a. Silver-Lead system
b. Water system
15s
Answer: b
Which of the following system is example for one component system
a. Silver-Lead system
b. Water system
15s
Answer: b
1) Areas
AOB, AOC, BOC
AOB Water
AOC Vapour
BOC Ice
P = 1
F = 3-P
F = 2
The system is bivariant, because to locate any point in an area temperature as well as pressure coordinates
need to be known
Phase diagram of water system
AOB, AOC, BOC
AOB Water
AOC Vapour
BOC Ice
P = 1
F = 3-P
F = 2
The system is bivariant, because to locate any point in an area temperature as well as pressure coordinates
need to be known
Phase diagram of water system
2) Boundary lines (curves)
Separating the areas are boundary
lines. OA, OB, OC
In boundary lines two phases can coexist equilibrium
P = 2
F = 3-P
F = 1
Any point on boundary line has one degree of freedom (univariant)
In order to locate any point at particular line either temperature or pressure coordinates should
be known For fixed value of one coordinate the second is automatically fixed
Phase diagram of water system
Separating the areas are boundary
lines. OA, OB, OC
In boundary lines two phases can coexist equilibrium
P = 2
F = 3-P
F = 1
Any point on boundary line has one degree of freedom (univariant)
In order to locate any point at particular line either temperature or pressure coordinates should
be known For fixed value of one coordinate the second is automatically fixed
Phase diagram of water system
Curve OA (Vaporization curve)
F = 3-P (P=2)
F = 3-2 = 1 (mono variant)
Curve OB (Melting point curve)
F = 3-P (P=2)
F = 3-2 = 1 (mono variant)
Curve OC (Sublimation curve)
F = 3-2 = 1 (mono variant)
Phase diagram of water system
F = 3-P (P=2)
F = 3-2 = 1 (mono variant)
Curve OB (Melting point curve)
F = 3-P (P=2)
F = 3-2 = 1 (mono variant)
Curve OC (Sublimation curve)
F = 3-2 = 1 (mono variant)
Phase diagram of water system
3) Triple point
The three curves OA, OB, OC meet at O, at which solid, liquid and vapour are simultaneously at
equilibrium
This point at 273.16 K (or 0.0098 °C, 4.579 mm of Hg pressure) is called
triple point Since three phases co exist, the system is invariant
F = 3-3 = 0
There is no degree of freedom at O
Phase diagram of water system
The three curves OA, OB, OC meet at O, at which solid, liquid and vapour are simultaneously at
equilibrium
This point at 273.16 K (or 0.0098 °C, 4.579 mm of Hg pressure) is called
triple point Since three phases co exist, the system is invariant
F = 3-3 = 0
There is no degree of freedom at O
Phase diagram of water system
Answer: C
REFLECTION SPOT-II
Degree of freedom at triple point
a. 2
b. 1
c. 0
15s
REFLECTION SPOT-II
Degree of freedom at triple point
a. 2
b. 1
c. 0
15s
SUMMARY
One component (water) system c=1
Phase rule equation: F=C-P+2 (or) F=1-P+2 OR (or) F=3-P
The number of phases that can exist in equilibrium at any time depends upon the
condition of pressure and temperature.
The phase diagram of one has following parts.
1) The curves OA,OB and OC (solid lines) where F=3-2=1
2) Three areas AOC,BOC and AOB. where F=3-1=2
3) Triple(Definite) point ’O’ where F=3-3=0
4) One meta stale curve OA’(dotted lines) where F=3-2=1
One component (water) system c=1
Phase rule equation: F=C-P+2 (or) F=1-P+2 OR (or) F=3-P
The number of phases that can exist in equilibrium at any time depends upon the
condition of pressure and temperature.
The phase diagram of one has following parts.
1) The curves OA,OB and OC (solid lines) where F=3-2=1
2) Three areas AOC,BOC and AOB. where F=3-1=2
3) Triple(Definite) point ’O’ where F=3-3=0
4) One meta stale curve OA’(dotted lines) where F=3-2=1
LECTURE OUTCOME REVISITED
LO1. explain one component system(Water System)
Having completed the discussion on
Application of phase rule to one component system
(water system)
LO1. explain one component system(Water System)
Having completed the discussion on
Application of phase rule to one component system
(water system)
Lecture Level practice Problems (LLPs)
LLP1:Observe the below given diagram and answer the following.
a.Is it one component phase diagram or two component diagram?
b.Mention the main features of the phase diagram
c.How many phases exist in each area, on each curve & at triple point and calculate
degrees of freedom at each part of the phase diagram
LLP1:Observe the below given diagram and answer the following.
a.Is it one component phase diagram or two component diagram?
b.Mention the main features of the phase diagram
c.How many phases exist in each area, on each curve & at triple point and calculate
degrees of freedom at each part of the phase diagram
FURTHER READING
Jain &Jain; Chapter 6 Topics: 09
Problems:
Jain &Jain; (pg.391),Topic:1
TUTORIAL NOTES
Jain &Jain; Chapter 6 Topics: 09
Problems:
Jain &Jain; (pg.391),Topic:1
TUTORIAL NOTES
Dr.T.Madhukar Reddy
Associate Professor
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic-21
W1 – L4-CDT-21
Topic:Application of phase rule to two component system
Silver-Lead system(Ag-Pb system) Pattinson’s process for desilverisation of lead
Associate Professor
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
Classroom Discussion Topic-21
W1 – L4-CDT-21
Topic:Application of phase rule to two component system
Silver-Lead system(Ag-Pb system) Pattinson’s process for desilverisation of lead
Lecture Outcome (LO)
After completion of this lecture, students will be
able to…
LO1. analyze two-component (silver-lead) system based on phase rule
and explain Pattinson’s process for desilverisation of lead
After completion of this lecture, students will be
able to…
LO1. analyze two-component (silver-lead) system based on phase rule
and explain Pattinson’s process for desilverisation of lead
Application of Phase rule to two component system (Ag-Pb system):
Ag-pb system is two component system i.e., C=2
In this system the possible phases are four
i.Ag (s) ii. Pb (s)
iii.solution of Ag & Pb iv. Ag-Pb vapour phase
The boiling point of Ag & Pb are very high. It indicates in this system vapour
phase is practically absent.as vapour phase is practically absent and one
variable pressure is neglected, the condensed system phase rule is:
F = C-P+1 but C=2
F= 2-P+1
F= 3-P
If P = 1 then F = 2 If P = 0 then F = 3
It indicates maximum degree of freedom of the system is three , three
dimentional diagram is required to define the system..as vapour phase is
practically absent and one variable pressure is neglected, the system
conveniently represented by a temperature-concentration diagram
Ag-pb system is two component system i.e., C=2
In this system the possible phases are four
i.Ag (s) ii. Pb (s)
iii.solution of Ag & Pb iv. Ag-Pb vapour phase
The boiling point of Ag & Pb are very high. It indicates in this system vapour
phase is practically absent.as vapour phase is practically absent and one
variable pressure is neglected, the condensed system phase rule is:
F = C-P+1 but C=2
F= 2-P+1
F= 3-P
If P = 1 then F = 2 If P = 0 then F = 3
It indicates maximum degree of freedom of the system is three , three
dimentional diagram is required to define the system..as vapour phase is
practically absent and one variable pressure is neglected, the system
conveniently represented by a temperature-concentration diagram
Phase diagram of two component system (Ag-Pb system)
Phase diagram of two component system (Ag-Pb system)
Curve AO (Freezing point curve of Ag)
This curve indicates that the melting point of Ag falls gradually on adding Pb along
AO till the lowest point O (303 °C) is reached, where the solution gets saturated
with respect to Pb
P = 2
F = 3-P = 3-2 = 1
F = 1 (mono variant)
This curve indicates that the melting point of Ag falls gradually on adding Pb along
AO till the lowest point O (303 °C) is reached, where the solution gets saturated
with respect to Pb
P = 2
F = 3-P = 3-2 = 1
F = 1 (mono variant)
Curve BO (Freezing point curve of Pb)
Represent the effect on freezing point of Pb on gradual addition of small
amount of Ag to it
Point B is the melting point of pure Pb (327 °C)
Along BO the melting point gradually falls on the addition of Ag, till lowest point
O is reached
P = 2
F = 3-P = 3-2 = 1
F = 1 (mono variant)
P(L)
Represent the effect on freezing point of Pb on gradual addition of small
amount of Ag to it
Point B is the melting point of pure Pb (327 °C)
Along BO the melting point gradually falls on the addition of Ag, till lowest point
O is reached
P = 2
F = 3-P = 3-2 = 1
F = 1 (mono variant)
P(L)
Point O (eutectic point)
At this point all the three phases Pb (s),
Ag (s) and solution coexist in equilibrium
P = 3, F = 3-P = 3-3 = 0
Non variant
The temperature corresponding to point O (303 °C) is the lowest possible
temperature for existence of liquid state. Below this temperature the total system
becomes solid
That means if a mixture of 2.6 % Ag + 97.4 % Pb is heated it simply melts at 303 °C
This temperature is called as eutectic temperature and composition is called as
eutectic composition and corresponding point is called as eutectic point
At this point all the three phases Pb (s),
Ag (s) and solution coexist in equilibrium
P = 3, F = 3-P = 3-3 = 0
Non variant
The temperature corresponding to point O (303 °C) is the lowest possible
temperature for existence of liquid state. Below this temperature the total system
becomes solid
That means if a mixture of 2.6 % Ag + 97.4 % Pb is heated it simply melts at 303 °C
This temperature is called as eutectic temperature and composition is called as
eutectic composition and corresponding point is called as eutectic point
Characteristics of Eutectic point
At this point three phases coexist in equilibrium
No mixture of Pb and Ag has a melting point lower than the eutectic temperature
If external pressure is changed eutectic temperature and composition also
changed
At this point three phases coexist in equilibrium
No mixture of Pb and Ag has a melting point lower than the eutectic temperature
If external pressure is changed eutectic temperature and composition also
changed
REFLECTION SPOT-I
Which of the following system is example for two component system
a. Silver-Lead system
b. Water system
15s
Answer: a
Which of the following system is example for two component system
a. Silver-Lead system
b. Water system
15s
Answer: a
PATTINSON’S PROCESS FOR DESILVERISATION
OF LEAD
It is a process of raising the relative amount of Ag in
Pb-Ag alloy
The argentiferous lead, consisting of a very small
amount of silver (say 0.1%), is heated to a
temperature above its melting point, so that the
system consisting of only the liquid phase
represented by the point ‘p’ in the Figure. It is then
allowed to cool
The temperature falls down along the line ‘pq’. As
soon as the point ‘q’ is reached. Pb is crystallised
out and the solution will contain relatively increasing
amount of ‘Ag’.
OF LEAD
It is a process of raising the relative amount of Ag in
Pb-Ag alloy
The argentiferous lead, consisting of a very small
amount of silver (say 0.1%), is heated to a
temperature above its melting point, so that the
system consisting of only the liquid phase
represented by the point ‘p’ in the Figure. It is then
allowed to cool
The temperature falls down along the line ‘pq’. As
soon as the point ‘q’ is reached. Pb is crystallised
out and the solution will contain relatively increasing
amount of ‘Ag’.
On further cooling, more and more ‘Pb’
is separated along the line ‘BO’ the
melt continues to be richer and richer
in silver until the point O is reached,
where the percentage of Ag rises to
2.6%
Thus, the process of raising the
relative proportion of Ag in the alloy is
known as Pattinson’s process
is separated along the line ‘BO’ the
melt continues to be richer and richer
in silver until the point O is reached,
where the percentage of Ag rises to
2.6%
Thus, the process of raising the
relative proportion of Ag in the alloy is
known as Pattinson’s process
Answer: c
REFLECTION SPOT-II
Degree of freedom at eutectic point
a. 2
b. 1
c. 0
REFLECTION SPOT-II
Degree of freedom at eutectic point
a. 2
b. 1
c. 0
SUMMARY
One component (water) system c=1
Phase rule equation: F=C-P+2 (or) F=1-P+2 OR (or) F=3-P
The number of phases that can exist in equilibrium at any time depends upon the
condition of pressure and temperature.
The phase diagram of one has following parts.
1)The stable curves OA,OB and OC (solid lines) where F=3-2=1
2)One meta stale curve OA’(dotted lines) where F=3-2=1
3) Three areas AOC,BOC and AOB. where F=3-1=2
4) Triple(Definite) point ’O’ where F=3-3=0
One component (water) system c=1
Phase rule equation: F=C-P+2 (or) F=1-P+2 OR (or) F=3-P
The number of phases that can exist in equilibrium at any time depends upon the
condition of pressure and temperature.
The phase diagram of one has following parts.
1)The stable curves OA,OB and OC (solid lines) where F=3-2=1
2)One meta stale curve OA’(dotted lines) where F=3-2=1
3) Three areas AOC,BOC and AOB. where F=3-1=2
4) Triple(Definite) point ’O’ where F=3-3=0
LECTURE OUTCOME REVISITED
LO1. analyze two-component (silver-lead) system
based on phase rule and explain Pattinson’s process
for desilverisation of lead
Having completed the discussion on
Application of phase rule to two component systemSilver-Lead system(Ag-Pb
system) Pattinson’s process for desilverisation of lead
LO1. analyze two-component (silver-lead) system
based on phase rule and explain Pattinson’s process
for desilverisation of lead
Having completed the discussion on
Application of phase rule to two component systemSilver-Lead system(Ag-Pb
system) Pattinson’s process for desilverisation of lead
Lecture Level practice Problems (LLPs)
LLP1:Observe the below given diagram and answer the following.
a.Is it one component phase diagram or two component phase diagram?
b.Mention the main features of the phase diagram .
c. Calculate degrees of freedom along AO and OB curves and at eutectic point.
LLP1:Observe the below given diagram and answer the following.
a.Is it one component phase diagram or two component phase diagram?
b.Mention the main features of the phase diagram .
c. Calculate degrees of freedom along AO and OB curves and at eutectic point.
FURTHER READING
Jain &Jain; Chapter 6 Topics: 09
Problems:
Jain &Jain; (pg.406),Topic:12
TUTORIAL NOTES
Jain &Jain; Chapter 6 Topics: 09
Problems:
Jain &Jain; (pg.406),Topic:12
TUTORIAL NOTES
Dr. H. Ramesh Babu
Dr.T. Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
CLASS ROOM DISCUSSION TOPIC -22
W6 – L2-CDT22
Topic: Knocking, Octane number
Dr.T. Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
CLASS ROOM DISCUSSION TOPIC -22
W6 – L2-CDT22
Topic: Knocking, Octane number
Lecture Outcomes (LOs)
After completion of this lecture, students will be
able to…
LO1. explain knocking, octane number
After completion of this lecture, students will be
able to…
LO1. explain knocking, octane number
KNOCKING
Due to the presence of some constituents in gasoline used, the rate of oxidation
becomes so great that the last portion of the fuel and air mixture get ignited
instantaneously producing an explosive violence, known as knocking at loss of
efficiency
The tendency of fuel constituents to knock is in the following order
Straight chain alkanes > Branched alkanes > Olefins > Cyclo alkane >
Napthalenes > Aromatics
Due to the presence of some constituents in gasoline used, the rate of oxidation
becomes so great that the last portion of the fuel and air mixture get ignited
instantaneously producing an explosive violence, known as knocking at loss of
efficiency
The tendency of fuel constituents to knock is in the following order
Straight chain alkanes > Branched alkanes > Olefins > Cyclo alkane >
Napthalenes > Aromatics
The tendency of fuel constituents to knock is in the following
order
Straight chain alkanes > Branched alkanes > Olefins > Cyclo alkane >
Napthalenes > Aromatics
order
Straight chain alkanes > Branched alkanes > Olefins > Cyclo alkane >
Napthalenes > Aromatics
Which of the following, the tendency of fuel constituents posses more
knocking tendency
a.Aromatics
b.Branched alkanes
c.Olefins
d.Straight chain alkanes
Answer: d
REFLECTION SPOT-I
15s
knocking tendency
a.Aromatics
b.Branched alkanes
c.Olefins
d.Straight chain alkanes
Answer: d
REFLECTION SPOT-I
15s
OCTANE NUMBER
Octane number (or) Octane rating (or) Anti
knocking rating
•It indicates the percentage of iso octane present in the given fuel.
•It is fixed to the given fuel by comparing the knocking properties of it
with the knocking properties of n-heptane, iso octane blends
•More octane number indicates less knocking
•Less octane number indicates more knocking property of the fuel
knocking rating
•It indicates the percentage of iso octane present in the given fuel.
•It is fixed to the given fuel by comparing the knocking properties of it
with the knocking properties of n-heptane, iso octane blends
•More octane number indicates less knocking
•Less octane number indicates more knocking property of the fuel
More octane number indicates less knocking, less octane number indicates more
knocking property of the fuel
n-heptane shows more knocking, its octane number is zero
CH3-(CH2)5-CH3
n-Heptane,Octane Number=0
Iso octane (2,2,4-trimethyl pentane) shows less knocking,
its octane number 100.
knocking property of the fuel
n-heptane shows more knocking, its octane number is zero
CH3-(CH2)5-CH3
n-Heptane,Octane Number=0
Iso octane (2,2,4-trimethyl pentane) shows less knocking,
its octane number 100.
OR
OCTANE NUMBER
OCTANE NUMBER
Improvemet of octane number i.e anti-knocking characteristics of a fuel:
Octane number of the fuel can be improved by the addition of tetra ethyl
lead(TEL) Pb(C
2H
5)
4, Di ehthyl telluride(C2H5 Te).
Addition of TEL petrol ( Leaded petrol) leads the formation of PbO (Lithrage)
during combustion which deposits on the inner walls of cylinder and jams the
piston.
Alternative method to imrove octane number of petrol is addition of high octane
compounds like isopentane ,Isooctane, Ethyl benzene, Isopropyl benzene, Methyl
Ter Butyl Ether (MTBE)
Among all these MTBE is preferred, because it contains oxygen in the form of
ether group and supplies oxygen for the combustion of petrol in IC engines.
Unleaded petrol is one where in the enhancement of octane rating is
accomplished without addition of lead compounds.
Octane number of the fuel can be improved by the addition of tetra ethyl
lead(TEL) Pb(C
2H
5)
4, Di ehthyl telluride(C2H5 Te).
Addition of TEL petrol ( Leaded petrol) leads the formation of PbO (Lithrage)
during combustion which deposits on the inner walls of cylinder and jams the
piston.
Alternative method to imrove octane number of petrol is addition of high octane
compounds like isopentane ,Isooctane, Ethyl benzene, Isopropyl benzene, Methyl
Ter Butyl Ether (MTBE)
Among all these MTBE is preferred, because it contains oxygen in the form of
ether group and supplies oxygen for the combustion of petrol in IC engines.
Unleaded petrol is one where in the enhancement of octane rating is
accomplished without addition of lead compounds.
OCTANE NUMBER
Octane number indicates the percentage of------------------
a. n-Pentane
b. n-Hexane
c. Iso Heptane
d. Iso Octane
15s
Answer: d
REFLECTION SPOT-II
a. n-Pentane
b. n-Hexane
c. Iso Heptane
d. Iso Octane
15s
Answer: d
REFLECTION SPOT-II
LECTURE OUTCOME REVISITED
LO1. explain knocking, octane number
LO1. explain knocking, octane number
SUMMARY
Knocking:Due to the presence of some constituents in gasoline used, the rate of oxidation
becomes so great that the last portion of the fuel and air mixture get ignited instantaneously
producing an explosive violence, known as knocking at loss of efficiency
The tendency of fuel constituents to knock is in the following order
Straight chain alkanes > Branched alkanes > Olefins > Cyclo alkane
> Napthalenes > Aromatics
Octane Number:
•It indicates the percentage of iso octane present in the given fuel.
•It is fixed to the given fuel by comparing the knocking properties of it with the knocking
properties of n-heptane, iso octane blends
Knocking:Due to the presence of some constituents in gasoline used, the rate of oxidation
becomes so great that the last portion of the fuel and air mixture get ignited instantaneously
producing an explosive violence, known as knocking at loss of efficiency
The tendency of fuel constituents to knock is in the following order
Straight chain alkanes > Branched alkanes > Olefins > Cyclo alkane
> Napthalenes > Aromatics
Octane Number:
•It indicates the percentage of iso octane present in the given fuel.
•It is fixed to the given fuel by comparing the knocking properties of it with the knocking
properties of n-heptane, iso octane blends
Lecture Level practice Problems (LLPs)
Problem 1: Why knocking in IC engines reduces the efficiency of engine? Explain.
Problem 2: Identify the reason for using unleaded gasoline in IC engine.
Problem 1: Why knocking in IC engines reduces the efficiency of engine? Explain.
Problem 2: Identify the reason for using unleaded gasoline in IC engine.
FURTHER READING
Jain &Jain; Chapter 6
Topics: 10, page-303
Jain &Jain; Chapter 6
Topics: 10, page-303
Dr. H. Ramesh Babu
Dr.T.Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
CLASS ROOM DISCUSSION TOPIC-23
W6 – L2-CDT23
TOPIC: CETANE NUMBER
Dr.T.Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
CLASS ROOM DISCUSSION TOPIC-23
W6 – L2-CDT23
TOPIC: CETANE NUMBER
Lecture Outcomes (LOs)
After completion of this lecture, students will be
able to…
LO1. explain Cetane number
After completion of this lecture, students will be
able to…
LO1. explain Cetane number
Cetane number
It indicates the suitability of diesel engine fuel, as fuel of diesel engine motors.
Good engine fuel should have less induction log, when diesel fuel posses more
percentage of n-Hexa decane that shows less induction log.
Less induction log: Minimize the delay of fuel injection into chamber.
It is observed that diesel with more percentage of 1-Methyl naphthalene pores
more induction log and less cetane number.
Cetane number of the given diesel is fixed by comparing its properties with the
properties of methyl naphthalene and n-hexa decane blends.
It indicates the suitability of diesel engine fuel, as fuel of diesel engine motors.
Good engine fuel should have less induction log, when diesel fuel posses more
percentage of n-Hexa decane that shows less induction log.
Less induction log: Minimize the delay of fuel injection into chamber.
It is observed that diesel with more percentage of 1-Methyl naphthalene pores
more induction log and less cetane number.
Cetane number of the given diesel is fixed by comparing its properties with the
properties of methyl naphthalene and n-hexa decane blends.
The cetane number of a diesel fuel is a measure of it as
an index of the Ignition Quality (Ignition delay
characteristics ) of diesel fuel which defines the way
combustion proceeds in the engine.
The cetane number is the most definitive way to
describe the quality of the combustion process in a
diesel engine
Cetane number
an index of the Ignition Quality (Ignition delay
characteristics ) of diesel fuel which defines the way
combustion proceeds in the engine.
The cetane number is the most definitive way to
describe the quality of the combustion process in a
diesel engine
Cetane number
Which of the following posses more cetane number
a.Iso hexa decane
b.n-hexa decane
c.1-methyl naphathalein
Answer: b
REFLECTION SPOT-I
15s
a.Iso hexa decane
b.n-hexa decane
c.1-methyl naphathalein
Answer: b
REFLECTION SPOT-I
15s
Order of Cetane number of Chemical constituents
n-alkanes > > > branched alkanes > Naphthalenes
n-alkanes > > > branched alkanes > Naphthalenes
Cetane number indicates the ------------------
15s
Answer: Suitability of fuel as diesel engine fuel
REFLECTION SPOT-II
15s
Answer: Suitability of fuel as diesel engine fuel
REFLECTION SPOT-II
LECTURE OUTCOME REVISITED
LO1. explain cetane number
LO1. explain cetane number
Cetane number
It indicates the suitability of diesel engine fuel, as fuel of diesel engine motors.
Good engine fuel should have less induction log, when diesel fuel posses more
percentage of n-Hexa decane that shows less induction log.
Less induction log: Minimize the delay of fuel injection into chamber.
It is observed that diesel with more percentage of 1-Methyl naphthalene pores
more induction log and less cetane number.
Cetane number of the given diesel is fixed by comparing its properties with the
properties of methyl naphthalene and n-hexa decane blends.
RECAP- EC CDT.23 CETANE NUMBER SUMMARY
It indicates the suitability of diesel engine fuel, as fuel of diesel engine motors.
Good engine fuel should have less induction log, when diesel fuel posses more
percentage of n-Hexa decane that shows less induction log.
Less induction log: Minimize the delay of fuel injection into chamber.
It is observed that diesel with more percentage of 1-Methyl naphthalene pores
more induction log and less cetane number.
Cetane number of the given diesel is fixed by comparing its properties with the
properties of methyl naphthalene and n-hexa decane blends.
RECAP- EC CDT.23 CETANE NUMBER SUMMARY
FURTHER READING
Jain &Jain; Chapter 2 Topics: 24(page 82)
Jain &Jain; Chapter 2 Topics: 24(page 82)
Dr. H. Ramesh Babu
Dr.T. Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
CLASS ROOM DISCUSSION TOPIC-24
W6 – L2-CDT24
TOPIC:CDT24: Compressed Natural Gas (CNG), Power Alcohol
Dr.T. Madhukar Reddy
Department of Physical Sciences
Kakatiya Institute of Technology and Science, Warangal, TS, India
U18CH103/203 ENGINEERING CHEMISTRY
CLASS ROOM DISCUSSION TOPIC-24
W6 – L2-CDT24
TOPIC:CDT24: Compressed Natural Gas (CNG), Power Alcohol
Lecture Outcomes (LOs)
After completion of this lecture, students will be
able to…
LO1. discuss the compressed natural gas (CNG),
power alcohol
After completion of this lecture, students will be
able to…
LO1. discuss the compressed natural gas (CNG),
power alcohol
compressed natural gas (CNG)
Compressed natural gas (CNG) is a fuel gas mainly
composed of methane (CH
4), compressed to less than
1% of the volume it occupies at standard atmospheric
pressure.
It is stored and distributed in hard containers at a
pressure of 20–25 megapascals (2,900–3,600 psi),
usually in cylindrical or spherical shapes
Compressed natural gas (CNG) is a fuel gas mainly
composed of methane (CH
4), compressed to less than
1% of the volume it occupies at standard atmospheric
pressure.
It is stored and distributed in hard containers at a
pressure of 20–25 megapascals (2,900–3,600 psi),
usually in cylindrical or spherical shapes
CNG (Compressed Natural Gas)
Less harmful gases are evolved when CNG is used as fuel, there fore less air
pollution is evolved
It is much safer fuel and ignited at higher temperature than that of diesel and
petrol
Composition
Methane 70-90%
Ethane 5-10%
Hydrogen 3%
CO, CO2: rest
Conversion of internal combustion engine to CNG engine is easily process
Less harmful gases are evolved when CNG is used as fuel, there fore less air
pollution is evolved
It is much safer fuel and ignited at higher temperature than that of diesel and
petrol
Composition
Methane 70-90%
Ethane 5-10%
Hydrogen 3%
CO, CO2: rest
Conversion of internal combustion engine to CNG engine is easily process
compressed natural gas (CNG)
compressed natural gas (CNG)
Compressed Natural Gas (CNG)
compressed natural gas (CNG)
CNG is used in traditional petrol/internal combustion engine vehicles that
have been modified, or in vehicles specifically manufactured for CNG use:
either alone (dedicated), with a segregated liquid fuel system to extend
range (dual fuel), or in conjunction with another fuel (bi-fuel). It can be used
in place of petrol (gasoline), diesel fuel, and liquefied petroleum gas (LPG).
CNG combustion produces fewer undesirable gases than the
aforementioned fuels. In comparison to other fuels, natural gas poses less
of a threat in the event of a spill, because it is lighter than air and disperses
quickly when released.
Biomethane – refined biogas from anaerobic digestion or landfills – can be
used.
compressed natural gas (CNG)
have been modified, or in vehicles specifically manufactured for CNG use:
either alone (dedicated), with a segregated liquid fuel system to extend
range (dual fuel), or in conjunction with another fuel (bi-fuel). It can be used
in place of petrol (gasoline), diesel fuel, and liquefied petroleum gas (LPG).
CNG combustion produces fewer undesirable gases than the
aforementioned fuels. In comparison to other fuels, natural gas poses less
of a threat in the event of a spill, because it is lighter than air and disperses
quickly when released.
Biomethane – refined biogas from anaerobic digestion or landfills – can be
used.
compressed natural gas (CNG)
The cost and placement of fuel storage containers is the major
barrier to wider/quicker adoption of CNG as a fuel.
It is also why municipal government, public transportation vehicles
were the most visible early adopters of it, as they can more quickly
amortize the money invested in the new (and usually cheaper)
fuel.
In spite of these circumstances, the number of vehicles in the
world using CNG has grown steadily (30 percent per year). Now,
as a result of the industry's steady growth, the cost of such fuel
storage cylinders has been brought down to a much more
acceptable level.
compressed natural gas (CNG)
barrier to wider/quicker adoption of CNG as a fuel.
It is also why municipal government, public transportation vehicles
were the most visible early adopters of it, as they can more quickly
amortize the money invested in the new (and usually cheaper)
fuel.
In spite of these circumstances, the number of vehicles in the
world using CNG has grown steadily (30 percent per year). Now,
as a result of the industry's steady growth, the cost of such fuel
storage cylinders has been brought down to a much more
acceptable level.
compressed natural gas (CNG)
Fill in the blank:
CNG mainly composed of ------------------gas
a. Ethane
b. Propane
c. Methane
d. n-Butane
15s
Answer: c
REFLECTION SPOT-I
CNG mainly composed of ------------------gas
a. Ethane
b. Propane
c. Methane
d. n-Butane
15s
Answer: c
REFLECTION SPOT-I
POWER ALCOHOL
Power alcohol
It is mixture of petrol (75-99%) and ethyl alcohol (25-1%)
It is used as a fuel for automobiles
Exhaust gases consists of low level of toxic, hence does not cause environmental
pollution
It is mixture of petrol (75-99%) and ethyl alcohol (25-1%)
It is used as a fuel for automobiles
Exhaust gases consists of low level of toxic, hence does not cause environmental
pollution
Power alcohol
15s
Answer: Petrol, Ethyl alcohol
REFLECTION SPOT-II
Fill in the Blanks
Power Alcohol is mixture of ----------(75-99%)
and ------------ (25-1%)
Answer: Petrol, Ethyl alcohol
REFLECTION SPOT-II
Fill in the Blanks
Power Alcohol is mixture of ----------(75-99%)
and ------------ (25-1%)
LECTURE OUTCOME REVISITED
LO1. discuss the compressed natural gas (CNG),
power alcohol
LO1. discuss the compressed natural gas (CNG),
power alcohol
Compressed Natural Gas (CNG)
SUMMARY
Power alcohol
Compressed natural gas (CNG) is a fuel gas mainly composed of methane (CH
4), compressed to less
than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard
containers at a pressure of 20–25 megapascals (2,900–3,600 psi), usually
in cylindrical or spherical shapes.
Compositionof CNG:Methane 70-90% Ethane 5-10% Hydrogen 3% CO, CO2: rest
It is mixture of petrol (75-99%) and ethyl alcohol (25-1%) It is used as a
fuel for automobiles
Exhaust gases consists of low level of toxic, hence does not cause environmental pollution
SUMMARY
Power alcohol
Compressed natural gas (CNG) is a fuel gas mainly composed of methane (CH
4), compressed to less
than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard
containers at a pressure of 20–25 megapascals (2,900–3,600 psi), usually
in cylindrical or spherical shapes.
Compositionof CNG:Methane 70-90% Ethane 5-10% Hydrogen 3% CO, CO2: rest
It is mixture of petrol (75-99%) and ethyl alcohol (25-1%) It is used as a
fuel for automobiles
Exhaust gases consists of low level of toxic, hence does not cause environmental pollution
FURTHER READING
Jain &Jain;)Chapter 2 Topics: 25(page 82)
Jain &Jain;)Chapter 2 Topics: 25(page 82)
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