3. INTRODUCTION: SOAP VS DETERGENTS
Water that contains calcium ions, Ca2+, and magnesium
ions, Mg2+, is said to be hard water. These ions are
leached from ground water flowing over rock
formations containing limestone and other minerals.
Hard water interferes with the cleaning action of soaps.
When soap is added to hard water, insoluble
compounds form which appear as sticky scum. This
scum leaves a deposit on clothes, skin, and hair. You
could have ring around the collar!
When boiled, hard water leaves a deposit of calcium
carbonate, CaCO3. This scale builds up in tea kettles and
inside hot water heaters.
Detergents have replaced soap for many cleaning jobs
around the home.
The development of synthetic detergents by chemists
was a great advantage for people with relatively hard
tap water in their homes.
4. DETERGENTS
DEFINITION :
Detergents are soap-like compounds which are used for cleaning purpose. They are
sodium salts of long chain alkyl benzene sulphonic acids or sodium salts of long chain alkyl
hydrogen sulphate, whereas, soaps are sodium salts of long chain carboxylic acids.
STRUCTURE OF DETERGENTS
5. Hydrophilic part: Hydrophilic part is sodium salt which is readily soluble in water. e.g.
–SO3-, –OSO3-, OH- or NR4. This part of a detergent is ionic and is attracted by polar
water molecules.
Hydrophobic part: hydrocarbon part of detergent is called hydrophobic part. It is non-
polar. Hydrophobic part is insoluble in water but it is soluble in oil. This part consists
of a hydrocarbon segment and can dissolve oil or grease.
Hydrophilic part (water soluble)
Hydrophobic part (oil soluble )
DETERGENTS
6. By combining animal or vegetable fats with aqueous sodium hydroxide soap is
made. Soaps are advantageous because they are made from biodegradable renewable
resources. Therefore, soaps are not polluting the environment. These factors are
outweighed by the negative affects of hard water and the cost of the raw materials. Soaps
react with calcium and magnesium ions in hard water leading to the formation of
precipitates. Increased household use of alkylbenzene sulfonates (ABS), a former
compound used in laundering with soaps, resulted in large bodies of water covered in
foam. The synthesis of ABS is shown below in Figure 1.
Figure: Synthesis of ABS
PREPARATION OF DETERGENT:
7. 1. Detergents are carbonic compounds which are not alkaline.
2. They are costly.
3. They are suitable for delicate clothes.
4. They clean both in hot and cold water.
5. They clean the cloth even in hard water.
6. They are removed very easily so less quantity of water is needed.
GENERAL PROPERTIES OF DERERGENT:
8. Chemical classification of detergents
1. Anionic detergents
2. Cationic detergents
3. Non-ionic and zwitterionic detergents
Chemical classification of detergents
9. 1. Anionic: Those that develop a negative charge on the water solubilizing end.
2. Cationic: Those that develop a positive charge on the water solubilizing end.
3. Non-Ionic: Those that develop no ionic charge on the water solubilizing end.
4. Amphoteric : Those that have both a positive and negative charged group on the
molecule.
Chemical classification of detergents By Ionic Charge
10. Anionic detergents
Typical anionic detergents
are alkylbenzenesulfonates. The alkylbenzene
portion of these anions is lipophilic and the sulfonate
is hydrophilic. Two varieties have been popularized,
those with branched alkyl groups and those with
linear alkyl groups.
The former were largely phased out in economically
advanced societies because they are poorly
biodegradable. An estimated 6 billion kilograms of
anionic detergents are produced annually for
domestic markets.
Bile acids, such as deoxycholic acid (DOC), are
anionic detergents produced by the liver to aid in
digestion and absorption of fats and oils.
Anionic detergents
11. Cationic detergents :
Cationic detergents are similar to the
anionic ones, with a hydrophobic
component, but, instead of the anionic
sulfonate group, the cationic surfactants
have quaternary ammonium as the polar
end. The ammonium center is positively
charged
Cationic detergents
12. Non-ionic and zwitterionic detergents
•Non-ionic detergents are characterized by their
uncharged, hydrophilic headgroups. Typical non-
ionic detergents are based on polyoxyethylene or
a glycoside. Common examples of the former
include Tween,Triton, and the Brij series. These
materials are also known as ethoxylates or
PEGylates). Glycosides have a sugar as their
uncharged hydrophilic headgroup. Examples
include octyl-thioglucoside and maltosides. HEGA
and MEGA series detergents are similar,
possessing a sugar alcohol as headgroup.
•Zwitterionic detergents possess a net zero
charge arising from the presence of equal
numbers of +1 and -1 charged chemical groups.
Examples include CHAPS.
Non-ionic and zwitterionic detergents
13. SOAP
STRUCTURE OF SOAP:
Soap ‘“is a substance called a surfactant that is used with water for washing
and cleaning a variety of objects. Detergent ‘“refers to any substance, soapy
or not, that aids in cleaning.
DEFINITION
14. All soaps and detergents are polar molecules, which allow for the cleansing action
of dirt in water. One end consists of a large non-polar hydrocarbon group that is
hydrophobic i.e., repels water but attracts oil and dirt particles. The other end has
a highly polar short group that is hydrophilic i.e., attracts water and not oil or dirt.
MECHANISM OF SOAP & DETERGENT:
15. Soap forms a colloidal solution in water and when soap is applied to the surface
of a wet dirty cloth, the non-polar long end hydrocarbon of soap attaches itself to
the dirt and grease.
The short polar or ionic end of the soap molecule remains attached to water
molecules. The latter form very small globules or structures called 'micelles' in
which the oily dirt particle is surrounded with the tails of soap molecules carrying
negative charge, while the polar head with positive charge interacts with the
water. The subsequent mechanical action of rubbing or tumbling dislodges the
dirt and grease. These are washed away with excess of water leaving the fabric
clean.
MECHANISM OF SOAP & DETERGENT:
17. In the industrial manufacture of
soap, tallow (fat from animals such
as cattle and sheep) or vegetable
fat is heated with sodium
hydroxide. Once the saponification
reaction is complete, sodium
chloride is added to precipitate the
soap. The water layer is drawn off
the top of the mixture and the
glycerol is recovered using vacuum
distillation.
PREPARATION OF SOAP:
PREPARATION OF SOAP:
One of the organic chemical reactions known to ancient man was the preparation of
soaps through a reaction called saponification. Natural soaps are sodium or potassium
salts of fatty acids, originally made by boiling lard or other animal fat together with lye
or potash (potassium hydroxide). Hydrolysis of the fats and oils occurs, yielding
glycerol and crude soap.
18. 1. Soap are made from fat and alkali by specification method
2. There are cheap.
3. There are not suitable for delicate clothes.
4. They are clean better in hot water.
5. They don't produce lather with hard water and are not able to clean the cloth.
6. Lot of water is needed to remove soap from the cloth.
GENERAL PROPERTIES OF SOAP:
19. Part I: Soap vs. Detergent in Hard Water
1. Add 100 mL of distilled (soft) water to a 250 mL beaker. Then add 2.0 g of
magnesium sulfate, MgSO4, and stir. Label this beaker hard water. You now
have prepared a stock solution of hard water.
2. Arrange three test tubes in a test-tube rack. Half-fill the first test tube with
distilled water (soft water). Half-fill the second tube with tap water. Half-fill
the third with hard water from the stock solution.
3. Using a metal spatula, add a pea-sized sample of solid soap from a bar of
commercial hand soap to each of the three test tubes. (Caution: Remember
after shaking several times to stop, release the pressure, re-stopper, and
shake.) Stopper and shake the first test tube. Ten shakes is adequate. On your
data sheet record the height of suds in the test tube as measured with a
centimeter scale. Draw a picture of the test tube; record all your observations
in the picture.
Part I: Soap vs. Detergent in Hard Water
20. 1. Repeat Step 3 for the other two test tubes. Shake each test tube in an identical
manner.
2. Dump and rinse the test tube containing the soap.
3. Repeat Steps 2 and 3, but use a pea-sized sample of a commercial detergent
instead of the soap.
4. Dump and rinse the test tubes containing the detergent.
5. Repeat Steps 2 and 3 using 20 drops (approximately 1.0 mL) of a commercial
hair shampoo in each of the three water samples.
6. Dump and rinse the test tubes containing the shampoo.
Part I: Soap vs. Detergent in Hard Water
21. Part II: Emulsifying Test
1. Place four test tubes in a test-tube rack. Half-fill each with hard water.
2. Add 3.0 mL of cooking oil to each of the four tubes.
3. Add nothing to Tube 1, add a pea-sized sample of hand soap to Tube 2, a pea-sized
sample of detergent to Tube 3, and 20 drops of shampoo to Tube 4.
4. Stopper and shake all tubes in an identical manner. Return the tubes to the test
tube rack.
5. On your data sheet draw a picture of the four test tubes; record all your
observations in the picture.
6. Dump and wash out the test tubes as directed by your teacher.
Part II: Emulsifying Test
22. Part III: Softening Hard Water by Precipitation
1. Obtain a 2.0 g sample of sodium carbonate, Na2CO3. Add it to the hard water
remaining in the 250 mL beaker.
2. Place the beaker and contents on a hot plate. Heat and stir for 5 min.
3. Remove the beaker and allow it to cool.
4. When the beaker is cool enough to handle, separate the solid precipitate from
the liquid using a filtering apparatus or centrifuge, as directed by your teacher.
5. Half-fill a clean test tube with the clear filtrate. Add a pea-sized sample of solid
hand soap to the test tube, stopper, and shake.
6. Record your observations.
7. Dispose of the filter paper and solid as directed by your teacher.
8. Clean up your bench area and return all materials to their proper places.
9. Wash hands thoroughly before leaving the laboratory.
Part III: Softening Hard Water by Precipitation
23. Conclusion:
By this assignment I have learned the basic difference of detergent & soap,
preparation of detergent & soap, Basic properties of detergent & soap, Classification
of detergent & soap. What I think it will helpful not only in our study but also in job
field.
Conclusion:
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