Contents 1. INTRODUCTION …………………………………

2. EXPERIMENT 1 …………………………………………. To note the time taken by the foam in each test tube to disappear i.e, its foaming capacity. 3. EXPERIMENT 2………………….

To compare the cleansing capacity by comparing the surface activity of soap.

4. LABORATORY WORK………………………………..

5. INFERENCE……………………………

6. BIBLIOGRAPHY……………………………

INTRODUCTION Soaps are sodium or potassium salts of higher fatty acids like stearic, palmitic and oleic acids can be either saturated or unsaturated. They contain a long hydrocarbon chain of about 10-20 carbon with one carboxylic acid group as the functional group. A soap molecule a tadpole shaped structure, whose ends have different polarities. At one end is the long hydrocarbon chain that is non-polar and hydrophobic, i.e., insoluble in water but oil soluble. At the other end is the short polar carboxylate ion which is hydrophilic i.e., water soluble but insoluble in oil and grease.

(Long Hydrocarbon Chain) Hydrophobic end Hydrophilic end When soap is shaken with water it becomes a soap solution that is colloidal in nature. Agitating it tends to concentrate the solution on the surface and causes foaming. This helps the soap molecules make a unimolecular film on the surface of water and to penetrate the fabric. The long non-polar end of a soap molecule that are hydrophobic, gravitate towards and surround the dirt (fat or oil with dust absorbed in it). The short polar end containing the carboxylate ion, face the water away from the dirt. A number of soap molecules surround or encircle dirt and grease in a clustered structure called 'micelles', which encircles such particles and emulsify them.

Cleansing action of soaps decreases in hard water. Hard water contains Calcium and magnesium ions which react with sodium carbonate to produce insoluble carbonates of higher fatty acids.

2C17H35COONa + Ca2+ (C17H35COO) 2Ca +2Na+ (Water soluble) (ppt.)

2C17H35COONa + Mg2+ (C17H35COO) 2Mg +2Na+ This hardness can be removed by addition of Sodium Carbonate.

Ca2++ Na2CO3 CaCO3 + 2Na+

Mg2++ Na2CO3 MgCO3 + 2Na+ TYPES OF SOAPS (1) Soft soaps : these are common soaps of potassium salts of fats. (2) Transparent soaps : they contain glycerol or an alcohol and are obtained by dissolving soap in alcohol and evaporating it afterwards. (3) Medicated soaps : these are soaps containing some substances of medical value like dettol & neem soap. (4) Shaving soaps : they are sodium potassium sterates giving lasting lather containing gum, glycerine (presents quick drying of lather) QUALITIES OF GOOD SOAP: (1) It must contain free alkali. (2) It must be soft i.e. it should give rich amount of foam. (3) It should lower the surface tension of water to good extent so that soap solution should penetrate easily into the cloth. (4) It should have its effect for a longer time which includes three aspects –

(a) the penetration should be good. (b) the foam should remain for a longer period. (c) Miscelles should be formed in a very short time after using

the soap.

EXPERIMENT 1 AIM: To note the time taken by the foam in each test tube to disappear i.e, its foaming capacity.

APPARATUS: 5 test tubes, 5 flat bottom flsks, test tube stand and stop watch. MATERIALS REQUIRED: 5 different samples of soap and distilled water THEORY: The foaming capacity of a soap sample depends upon the nature of soap and its concentration. This can be compared for various samples of soaps by taking the same concentration of solution and shaking them. The foam is formed and the time taken for disappearances of foam in all cases is compared. The lesser the time taken by a solution for the disappearance of foam, the lower is its foaming capacity. PROCEDURE:

1. Five flat bottom flasks are taken and numbered 1 to 5. 2. In each of these flasks equal amounts (say 5 gm) of the given 3. samples of soap shavings or granules are taken and 75 ml of distilled

water is added. 4. Dissolve all the soap. 5. In a test-tube stand, five big clean and dry test tubes are taken and

numbered 1 to 5. 6. One ml of the five soap solution is then poured in the test tubes of

corresponding number. 7. Equal shakes are given to every soap solution by keeping the thumb on

the mouth of test tube. 8. The length of the foam produced in each test tube is measured and

tabulated. 9. As soon as the foam is formed, each test tube is fixed vertically and the

time taken of fixing is noted. 10. Allow the foam to settle down till most of it had disappeared. The

difference of both times give the time taken by each foam to disappear.

EXPERIMENT 2

AIM: To compare the cleansing capacity by comparing the surface activity of soap. THEORY: Soap lowers surface tension of water. Soap solution can therefore, spread through the fibers of the cloth readily, thus loosening dirt which is absorbed by soap solution (colloidal) and washed away. Cleaning effect of some examples of soap can, therefore,be compared in terms of lowering of surface tension of water by them. Better soap lowers the surface tension to a larger extent. Surface tension of soap solution can be easily compared by counting the number of drops formed from equal volumes of the soap solutions. APPARATUS: burette, test tubes, conical flasks. PROCEDURE:

(1) Take initial solution of soap sample 1 (i.e 5gm in 75ml) and fill it in a burette.

(2) Slowly open the stopcock. When drops start falling at a very slow rate, count the no. of drops for a volume of 1ml. Note the no. of drops in a table.

(3) Wash the burette and repeat the same process for other soap samples.

LABORATORY WORK TABLE 1 Soap no. 1 Surf excel Soap no. 2 Tide Soap no. 3 555 Soap no. 4 Henko

TABLE 2 S.NO. SOAP SOLUTION FOAM LENGTH TIME TAKEN BY FOAM

TO SETTLE DOWN

1 Surf excel 3.3 cm 8hrs 30min 2 Tide 4cm 8hrs 40min 3 555 3.5cm 8hrs 36min 4 Henko 5.1cm 9hrs 50min 5 Fena 2.5cm 7hrs 55min TABLE 3 S.NO. SOAP SOLUTION NO. OF DROPS 1 Surf excel 44 2 Tide 43 3 555 55 4 Henko 46 5 Fena 50

INFERENCE It is clear from the observation table that maximum foam is formed in the case of soap no. 4 i.e HENKO because in all other case the length of the foam is less. So it is proved that soap no. 4 has maximum capacity of foam. The time taken for the foam to settle also varies in different soaps. The foam made from the soap solution of HENKO soap disappears much later than the foam made by other soap solutions.

Soap no. 5 Fena

Hence it is proved that from a list of soaps i.e surf excel, henko, tide, 555 & fena, the maximum foaming capacity has hanko.

BIBLIOGRAPHY:: WEBSITES

www.wikipedia.com www.icbse.com chemistry textbook (part 1 & 2), NCERT, Central Board of

Secondary education