Aim: To compare the foaming capacities of five different commercial soaps. Apparatus: 5 test tubes, 5 conical flasks (100 ml), test tube stand, Bunsen burner 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: Five conical flasks (100 ml each) are taken and numbered 1 to 5. In each of these flasks equal amounts (say 5 gm) of the given samples of soap shavings or granules are taken and 50 ml of distilled water is added. Each conical flask is heated few minutes to dissolve all the soap completely. In a test-tube stand, five big clean and dry test tubes are taken and numbered 1 to 5 One ml of the five soap solution is then poured in the test tubes of corresponding number. 10 ml. of distilled water is then added to each test tube.
Test tube no 1 is then shaken vigorously 5 times.
The foam would be formed in the empty space above the container. Stop watch is started immediately and the time taken for the disappearance of foam is noted. Similarly the other test tubes are shaken vigorously for equal number of times (i.e., 5 times) with approximately with the same force and the time taken for the disappearance of foam in each case is recorded. The lesser the time taken for the disappearance of foam, the lower is the foaming capacity. Observation:
Amount of each soap sample taken = 5gm
Amount of distilled water taken = 1.00ml
Volume of each soap solution taken = 10 ml
Volume of distilled water added =
S. No. Soap Sample Time taken (seconds) i.e, 1,2,3,4,5.
Conclusions: The soap for which the time taken for the disappearance of foam is highest has maximum foaming capacity and is the best quality soap among the soaps tested.
Aim: Study the effect of the addition of Sodium Carbonate (Washing Soda) on the foaming capacity of different soap solutions. Apparatus: 3 test tubes, test tube stand, Bunsen burner and stop watch. Materials Required: 0.5 g sample of soap, water (distilled & tap both) and M/10 Na2CO3 solution. Theory: When sodium or potassium soaps are put into water containing calcium and magnesium ions (Hard water), results in formation of scum which applies grey appearance on the cloth. To achieve the same washing or cleaning action, more soap must be added. 2C17H35COONa +Ca2+ (C17H35COO) 2 Ca +2Na+
(Water soluble) (scum)
Hard water is water that has high mineral content (mainly calcium and magnesium ions) (in contrast with soft water). Hard water minerals primarily consist of calcium (Ca2+), and magnesium (Mg2+) metal cations, and sometimes other dissolved compounds such as bicarbonates and sulphates. Calcium usually enters the water as either calcium carbonate (CaCO3), in the form of limestone and chalk, or calcium sulphate (CaSO4), in the form of other mineral deposits. When Na2CO3 is added to tap water the calcium (Ca2+), and magnesium (Mg2+) ions precipitate as their carbonates .i.e. foaming capacity of soap increases. Ca2++ Na2CO3 CaCO3 + 2Na+
Mg2++ Na2CO3 MgCO3 + 2Na+
Procedure: Dissolve 0.5g of soap and dissolve it in 50 ml of distilled water. Take three test tubes and add distilled water in first, tap water in second and third test tube. Add 5 ml of M/10 sodium carbonate to third test tube.
To above test tubes add soap solutions separately.
Now shake first test tubes for formation of foam.
Now start the stop watch to calculate time taken for disappearance of foam. Similarly, perform the experiment with other soap solutions. Record the observations in a tabular form. Observation:
Amount of each soap sample taken= 0.5gm
Amount of distilled water taken= 50 ml.
Volume of each soap solution taken= 1 ml.
Volume of distilled water added = 10 ml.
Conclusions: Foaming capacity of soap in maximum in distilled water. The foaming capacity of soap increases on the addition of Sodium Carbonate.