Soaps and detergents

soaps their categories are well defined. process of micellisation

2. SOAP
•Introduction
•Saponification
•Soap molecule (Micelles)
•Cleansing action of soaps
•Advantages and
disadvantages
DETERGENT
•Introduction
•Classification of
detergents
•Cleansing action of
detergents
•Advantages and
disadvantages of
detergents
DIFFERENCES
BETWEEN SOAPS AND
DETERGENTS

3. Soaps are the sodium and potassium salts of
the long chain carboxylic acid. A soap
molecule consists of a long hydrocarbon
chain (composed of carbons and hydrogen's)
with a carboxylic acid on one end which is
ionic bonded to metal ion usually a sodium or
potassium.

4. A soap has a large non-ionic hydrocarbon group and an
ionic group COO-Na+.
 It is a salt of a strong base (NaOH) and a weak acid
(carboxylic acid), so a solution of soap in water is basic
in nature.

5. Sodium stearic (Chemical formula:
C17H35COO-Na+)
Sodium stearic soap is the sodium salt of a long chain
saturated fatty acid called stearic acid. Sodium stearic
soap has along alkyl group (C
17
H
35
) and an ionic
carboxylate group (COO
-
Na
+
).

6. Sodium palmitate  (Chemical formula :
C15H31COO-Na+)
Sodium Palmitate ‘soap’ is the sodium salt of long
chain saturated fatty acid called stearic acid
(C
15
H
31
COOH).

7. A soap molecule is made up of two parts : a long
hydrocarbon part and a short ionic part containing COO
-
Na
+
group. The soap molecule is said to have a tadpole
structure.

8. A soap molecule has two ends
with different properties-
1.A long hydrocarbon part which
is hydrophobic (i.e. it dissolves
in hydrocarbon).
2.A short ionic part containing
COO-Na+ which is hydrophilic
(i.e. it dissolves in water).
micelle

10. The process of making soap by the
hydrolysis of fats and oils with alkalies is
called saponification.
Soap is made by heating animal fats or
vegetable oil with concentrated sodium
hydroxide (NAOH).
Fat or Oil + NaOH → Soap + Glycerol

11. When a dirty cloth is put is put in
water containing soap than the
hydrocarbon ends of the soap
molecule in the micelle attach to
the oil or grease particles present
on the surface of dirty cloth. In this
way the soap micelles entraps the
oily particles by using the
hydrocarbon ends. The ionic ends
of the soap molecules remain
attached to the water when the
dirty cloth is agitated in soap
solution. The oily particles presents
on its surface gets dispersed in the
water due to which the cloth gets
clean.

12. We use soaps on daily basis.
Following are some uses
of soaps:-
Washing hands
Washing clothes
Cleaning utensils

13.  ADVANTAGES
Soaps are
eco-friendly
and bio
degradable
DISADVANTAGES
Soaps are not
suitable in the
hard water.
They have weak
cleansing
properties than
detergents.

14. LIMITATIONS OF SOAPS :-
Hard water contains calcium and magnesium salts. Soap is not
suitable for washing clothes with hard water because of two
reasons :-
When soap is used for washing clothes with hard water, a large
amount of soap is wasted in reacting with the calcium and
magnesium ions of hard water to form an insoluble precipitate
called scum, before it can be used for the real purpose of
washing .
So a larger amount of soap is needed for washing clothes when
the water is hard.
The scum (or the curdy precipitate) formed by the action of
hard water on soap, sticks to the clothes being washed and
interferes with the cleaning ability of the additional soap. This
makes the cleaning of clothes difficult.

15. Detergents are defined as ammonium,
sulphonate or sulphate salts of long
chain hydrocarbon containing 12-18
carbon atoms.
Detergents are soap less soaps because
they have all the properties of soaps but
actually they do not contain any soap.
More common detergents are the
sodium salt of long chain sulphonic
acid.

16. Detergents are primarily surfactants, which
could be produced easily from petrochemicals.
Surfactants lower the surface tension of water,
essentially making it 'wetter' so that it is less
likely to stick to itself and more likely to interact
with oil and grease.
The ionic group in a detergent is SO3¯Na⁺
They can be used in hard water as they do not
form curdy white precipitates (scum) with hard
water.

18. These are so called because a large
part of their molecule are anions and it
is the anionic part of the molecule
which is involved in cleansing action.
Anionic detergents are of two types:
1.Sodium alkyl sulphate
2.Sodium alkyl benzene sulphonate
These are used in toothpaste.

19. They are obtained from long straight
chain alcohols containing 12-18 carbon
atoms.
Example: Sodium lauryl sulphate and
sodium stearyl sulphate

20. They are 100% biodegradable
These detergents are also effective in
slightly acidic medium since they form
alkyl hydrogen sulphated which are
soluble material whereas soaps react
with acidic solution to form insoluble
fatty acid.

21. These detergents are sodium salt of long
chain alkyl benzene sulphonic acids.
Most widely used domestic detergent is
sodium 4-(1-dodecyl) benzene
sulphonate (SDS).

22. These are so named because the major
part of their molecule is cation and it is
the cationic part which is involved in
cleansing.
They are also called as invert soaps.
These are quaternary ammonium salts
(bromide, chloride, acetate) containing
one or more long chain alkyl group.

23. They are more expensive than anionic
detergents.
They possess germicidal properties thus
used in hospitals.
Example: cetyl trimethyl ammonium
bromide
They are used in hair shampoos and hair
conditioner.

24. They do not contain any ions.
They are esters of high molecular mass
alcohol obtained by reaction between
polyethylene glycol and stearic acid.
Example: Polyethylene glycol stearate
Liquid dishwashing detergents are of non
ionic type.

25. Synthetic detergents have the same type of molecular
structure as soaps i.e., one large non-polar hydrocarbon
group that is water repelling (hydrophobic) and one short
ionic group usually containing the  group that is water
attracting (hydrophilic).
 Thus the cleansing action is exactly similar to that of
soaps whereby the formation of micelles.
 However, synthetic detergents can lather well even in hard
water. This is because they are soluble sodium or
potassium salts of sulphonic acid or alkyl hydrogen
sulphate.
 Detergents form soluble calcium or magnesium salts on
reacting with the calcium ions or magnesium ions present
in water. This is a major advantage of the cleansing
property of detergents over soap.

26. •Detergents can be used even with hard water whereas
soaps are not suitable for use with hard water.
•Detergents have a stronger cleansing action than soaps.
•Detergents are more soluble in water than soaps.
•Detergents can be used in acidic medium while soaps
get precipitated in acidic medium.

27. Many detergents are resistant to the action of
biological agents and thus are not biodegradable.
Their elimination from municipal wastewaters by
the usual treatments is a problem.
They have a tendency to produce stable foams in
rivers that extend over several hundred meters of the
river water. This is due to the effects of surfactants
used in their preparation. Thus they pose a danger to
aquatic life.
Detergents consist of side chains which stop bacteria
from attacking and breaking the chain . This results
in slow degradation of detergent molecule leading to
their accumulation.

28. SOAPS
They are metal salts of
long chain higher fatty
acids.
These are prepared from
vegetable oils and
animal fats.
They cannot be used
effectively in hard water
as they produce scum
i.e., insoluble
precipitates of Ca2+,
Mg2+, Fe2+ etc.
DETERGENTS
These are sodium salts of
long chain hydrocarbons like
alkyl sulphates or alkyl
benzene sulphonates.
They are prepared from
hydrocarbons of petroleum or
coal.
These do not produce
insoluble precipitates in hard
water. They are effective in
soft, hard or salt water.