typesofoxides-220803eryre084117-a54c0175.ppt

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2. What is an oxide?
• An oxide is a compound of oxygen and
another element.
• There are four types of oxides:
- acidic oxides
- basic oxides
- amphoteric oxides
- neutral oxides

3. Acidic Oxides
• Non-metals may form acidic oxides.
• Most acidic oxides dissolve in water to
form an acid.
• One example is sulphur dioxide, which
dissolves readily in water to form sulphurous
acid.
• Acidic oxides are often gases at room
temperature.

4. Acidic oxideFormula Physical
state
Acid produced in
water
Name formula
Carbon dioxideCO
2
Gas Carbonic
acid
H
2CO
3
Sulphur
trioxide
SO
3
Gas Sulphuric
acid
H
2SO
4
Phosphorus(V)
oxide
P
4O
10
solid Phosphoric
acid
H
3PO
4
Example:
SO
2(g) + H
2O(l)  H
2SO
3(aq)
sulphur dioxide + water  sulphurous acid
Acidic Oxides

5. • Acidic oxides do not react with acids.
• However, they react with alkalis to form a salt
and water.

Example:
SO
2
(g) + 2NaOH(aq)  Na
2
SO
3
(aq) + H
2
O(l)
sulphur dioxide + sodium hydroxide
 sodium sulphite +
water
Acidic Oxides

6. Oxides
Acidic
oxide

oxides
of non-
metals
SO
2,
CO
2

SO
3
acids
alkalis
e.g. SO
2
+ H
2
O H
2
SO
3
(sulphurous acid)

CO
2
+ H
2
O H
2
CO
3
(carbonic acid)
SO
3 + H
2O H
2SO
4 (sulphuric acid)
w
a
t
e
r
salt + water
CO
2 + Ca(OH)
2 CaCO
3 + H
2O

SO
2 + Ca(OH)
2 CaSO
3 + H
2O
SO
3 + NaOH Na
2SO
4 + H
2O
CO
2
turned limewater
chalky due to the
formation of calcium
carbonate which is an
insoluble solid.

7. Basic Oxides
• The oxides of metals are basic oxides.
• Most basic oxides are insoluble in water.
• Basic oxides are often solids at room
temperature.
• A few oxides, such as sodium oxide and
potassium oxide, dissolve readily in water.
They are called alkalis.

8. Examples:
• When calcium oxide (quicklime) is added to
water, a vigorous reaction occurs.
• Calcium hydroxide (limewater) is formed,
which is sparingly soluble in water.
Basic Oxides

9. • Basic oxides react with acids to form a salt and
water.
Example:
CaO(s) + 2HNO
3(aq)  Ca(NO
3)
2(aq) + H
2O(l)
calcium oxide + nitric acid
 calcium nitrate + water
This is a neutralisation reaction.
Basic Oxides

10. Oxides
Basic
oxide

oxides of
metals
CaO
CuO
Na
2
O
acids
w
a
t
e
r
salt + water
CaO + HNO
3

MgO + H
2
SO
4
alkalis
(only some
basic oxide
dissolves in
water)
Na
2O + H
2O 2NaOH
CuO + H
2
O no reaction
Ca(NO
3)
2 + H
2O
MgSO
4
+ H
2
O
2

11. • Zinc oxide is an example of an amphoteric
oxide.
• Amphoteric oxides are metallic oxides that
react with both acids and bases to form salts
and water.
Amphoteric Oxides

12. Reaction 1: 2HCl(aq) + ZnO(s)  ZnCl
2
(aq) + H
2
O(l)
hydrochloric acid + zinc oxide  zinc chloride + water
In reaction (1), zinc oxide behaves as a basic oxide.
Reaction 2: 2NaOH(aq) + ZnO(s)  Na
2
ZnO
2
(aq) + H
2
O(l)
sodium hydroxide + zinc oxide  sodium zincate + water
In reaction (2), it behaves as an acidic oxide.
Amphoteric Oxides
In both reactions, a salt and water are formed.
Examine these reactions

13. Oxides
amphoteric
oxide
ZnO
Al
2
O
3

PbO
salt + water
salt + water
a
lk
a
lis
a
c
i
d
s
ZnO + HCl
Al
2O
3 + HNO
3
PbO + H
2SO
4
ZnCl
2
+ H
2
O2
Al(NO
3
)
3
+

H
2
O3
PbSO
4
+ H
2
O
Zinc oxide + sodium hydroxide
Aluminium oxide + sodium hydroxide

Lead (II) oxide + sodium hydroxide
Sodium aluminate + water
Sodium plumbate + water
sodium zincate + water

14. Neutral Oxides
• Some non-metals form oxides that show neither
basic nor acidic properties.
• These oxides are called neutral oxides and they are
insoluble in water.
• Examples: Water (H
2O), Carbon monoxide (CO),
Nitric oxide (NO)

15. Oxides
Acidic
oxide

oxides
of non-
metals
SO
2,
CO
2

SO
3
acids
alkalis
w
a
t
e
r
salt + water
Basic
oxide
Oxides of
metal
water
alkalis
a
c
i
d
s
salt + water
CaO
CuO
Na
2O
Amphoteric
oxide
ZnO
Al
2
O
3

PbO
acids
a
l
k
a
l
i
s
salt + water
salt + water
Neutral oxide
Oxides of
non-metals
Does not react with
acids or alkalies
CO
H
2
O
NO