Chemistry Project on Foaming Capacity of Soaps

Submitted by Editor

Foaming Capacity Of Soaps

Lourdes Central School,

Bejai, Mangalore

Investigatory Project


Foaming Capacity

Of Soaps

Kenneth Lobo

Class XII


Acknowledgements 3

Preface 4

Introduction 5

Commercial preparation 6

Introduction to experiment 9

Objective and theory 10

Procedure 11

Observation table 12

Result 13

Test for hardness 14

Bibliography 15


I will treasure the knowledge imparted to me by

Mrs. Anita Thomas, my grateful thanks to her for the able teaching and guidance. I thank Mr. Harsha Kumar, the Lab assistant for his cooperation.

I also thank my parents and my friends for their constant support and cooperation.


Soaps and detergents remove dirt and grease from skin and clothes. But all soaps are not equally effective in their cleaning action. Soaps are the Na and K salts of higher fatty acids such as Palmitic acid, Stearic acid and Oleic acid.

The cleansing action of soaps depends on the solubility of the long alkyl chain in grease and that of the -COONa or the -COOK part in water.

Whenever soap is applied on a dirty wet cloth, the non polar alkyl group dissolves in grease while the polar -COONa part dissolves in water. In this manner, an emulsion is formed between grease and water which appears as foam.

The washing ability of soap depends on foaming capacity, as well as the water used in cleaning. The salts of Ca and Mg disrupt the formation of micelle formation. The presence of such salts makes the water hard and the water is called hard water. These salts thus make the soap inefficient in its cleaning action.

Sodium Carbonate when added to hard water reacts with Ca and Mg and precipitates them out. Therefore sodium carbonate is used in the treatment of hard water.

This project aims at finding the foaming capacity of various soaps and the action of Ca and Mg salts on their foaming capacity.


Soap is an anionic surfactant used in conjunction with water for washing and cleaning, which historically comes either in solid bars or in the form of a viscous liquid. Soap consists of sodium or potassium salts of fatty acids and is obtained by reacting common oils or fats with a strong alkaline in a process known as saponification. The fats are hydrolyzed by the base, yielding alkali salts of fatty acids (crude soap) and glycerol.

The general formula of soap is

Fatty end water soluble end

CH3-(CH2) n -              COONa

Soaps are useful for cleaning because soap molecules have both a hydrophilic end, which dissolves in water, as well as a hydrophobic end, which is able to dissolve non polar grease molecules. Applied to a soiled surface, soapy water effectively holds particles in colloidal suspension so it can be rinsed off with clean water. The hydrophobic portion (made up of a long hydrocarbon chain) dissolves dirt and oils, while the ionic end dissolves in water. The resultant forms a round structure called micelle. Therefore, it allows water to remove normally-insoluble matter by emulsification.

Commercial production of soap

The most popular soap making process today is the cold process method, where fats such as olive oil react with strong alkaline solution, while some soapers use the historical hot process.

Handmade soap differs from industrial soap in that, usually, an excess of fat is sometimes used to consume the alkali (super fatting), and in that the glycerin is not removed, leaving a naturally moisturizing soap and not pure detergent. Often, emollients such as jojoba oil or Shea butter are added 'at trace' (the point at which the saponification process is sufficiently advanced that the soap has begun to thicken), after most of the oils have saponified, so that they remain unreacted in the finished soap.

Fat in soap

Soap is derived from either vegetable or animal fats. Sodium Tallowate, a common ingredient in much soap, is derived from rendered beef fat. Soap can also be made of vegetable oils, such as palm oil, and the product is typically softer.

An array of saponifiable oils and fats are used in the process such as olive, coconut, palm, cocoa butter to provide different qualities. For example, olive oil provides mildness in soap; coconut oil provides lots of lather; while coconut and palm oils provide hardness. Sometimes castor oil can also be used as an ebullient.

Smaller amounts of unsaponifable oils and fats that do not yield soap are sometimes added for further benefits.

Preparation of soap

In cold-process and hot-process soap making, heat may be required for saponification.

Cold-process soap making takes place at a sufficient temperature to ensure the liquification of the fat being used.

Unlike cold-processed soap, hot-processed soap can be used right away because the alkali and fat saponify more quickly at the higher temperatures used in hot-process soap making. Hot-process soap making was used when the purity of alkali was unreliable.

Cold-process soap making requires exact measurements of alkali and fat amounts and computing their ratio, using saponification charts to ensure that the finished product is mild and skin-friendly.

Hot process

In the hot-process method, alkali and fat are boiled together at 80–100 °C until saponification occurs, which the soap maker can determine by taste or by eye.

After saponification has occurred, the soap is sometimes precipitated from the solution by adding salt, and the excess liquid drained off. The hot, soft soap is then spooned into a mold.

Cold process

A cold-process soap maker first looks up the saponification value of the fats being used on a saponification chart, which is then used to calculate the appropriate amount of alkali. Excess unreacted alkali in the soap will result in a very high pH and can burn or irritate skin. Not enough alkali and the soap are greasy.

The alkali is dissolved in water. Then oils are heated, or melted if they are solid at room temperature. Once both substances have cooled to approximately 100-110°F (37-43°C), and are no more than 10°F (~5.5°C) apart, they may be combined. This alkali-fat mixture is stirred until "trace". There are varying levels of trace. After much stirring, the mixture turns to the consistency of a thin pudding. "Trace" corresponds roughly to viscosity. Essential and fragrance oils are added at light trace.

Introduction to the experiment

Soap samples of various brands are taken and their foaming capacity is noticed.

Various soap samples are taken separately and their foaming capacity is observed. The soap with the maximum foaming capacity is thus, said to be having the best cleaning capacity.

The test requires to be done with distilled water as well as with tap water. The test of soap on distilled water gives the actual strength of the soaps cleaning capacity. The second test with tap water tests the effect of Ca2+ and Mg2+ salts on their foaming capacities.

Objective: To compare the foaming capacity of various soaps.

Theory: The foaming capacity of soap depends upon the nature of the soap and its concentration. This may be compared by shaking equal volumes of solutions of different samples having the same concentration with same force for the same amount of time. The solutions are then allowed to stand when the foam produced during shaking disappears gradually. The time taken for the foam to disappear in each sample is determined. The longer the time taken for the disappearance of the foam for the given sample of soap, greater is its foaming capacity or cleansing action.

Requirements: Five 100ml conical flasks, five test tubes, 100ml measuring cylinder, test tube stand, weighing machine, stop watch.

Chemical Requirements: Five different soap samples, distilled water, tap water.


1. Take five 100ml conical flasks and number them 1,      2,3,4,5. Put 16ml of water in each flask and add 8 Gms of soap.

2. Warm the contents to get a solution.

3. Take five test tubes; add 1ml of soap solution to 3ml of water.

Repeat the process for each soap solution in different test tubes.

4. Close the mouth of the test tube and shake vigorously for a minute. Do the same for all test tubes and with equal force.

5. Start the timer immediately and notice the rate of disappearance of 2mm of froth.

Observations: The following outcomes were noticed at the end of the experiment

Test Tube no Vol. of soap solution Vol. of water added Time taken for disappearance of 2mm
1.    Dove 8ml 16ml 11’42”
2.    Lux 8ml 16ml 3’28”
3.    Tetmosol 8ml 16ml 5’10”
4.    Santoor 8ml 16ml 15’32”
5.    Cinthol 8ml 16ml 9’40”


The cleansing capacity of the soaps taken is in the order:

Santoor > Dove > Cinthol > Tetmosol > Lux

From this experiment, we can infer that Santoor has the highest foaming capacity, in other words, highest cleaning capacity.

Lux, on the other hand is found to have taken the least amount of time for the disappearance of foam produced and thus is said to be having the least foaming capacity and cleansing capacity.

Test for hardness in water

Test for Ca2+ and Mg2+ salts in the water supplied

Test for Ca2+ in water

H2O +NH4Cl + NH4OH + (NH4)2CO3

No precipitate

Test for Mg2+ in water

H2O +NH4Cl + NH4OH + (NH4)3PO4

No precipitate

The tests show negative results for the presence of the salts causing hardness in water. The water used does not contain salts of Ca2+ and Mg2+. The tap water provided is soft and thus, the experimental results and values hold good for distilled water and tap water.


Parts of this project have been referred from foreign sources and have been included in this investigatory project after editing.

The references of the sources are as follows:


Together With Lab Manual Chemistry-XII

Comprehensive Chemistry - 12

Internet sources:

Structure of soap molecule and micelle formation

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