Advertisements
Advertisements
Question
Explain the action of soap in removing an oily spot from a piece of cloth.
Solution
Cleansing action of soaps:
The oily spot present on clothes is organic in nature and insoluble in water. Therefore, it cannot be removed by only washing with water. When soap is dissolved in water, its hydrophobic ends attach themselves to the oily spot and remove it from the cloth. Then, the molecules of soap arrange themselves in the form of micelle and trap the dirt at the centre of the cluster. These micelles remain suspended in the water. Hence, the oily spots are easily rinsed away by water.
APPEARS IN
RELATED QUESTIONS
In a locality, hard water, required for an experiment, is not available. However, the following salts are available in the school laboratory:
1. Sodium sulphate
2. Calcium sulphate
3. Magnesium chloride
4. Sodium chloride
5. Calcium chloride
6. Potassium sulphate
Which of the above salts may be dissolved in water to obtain hard water for the experiment?
(A) 2, 3 and 5
(B) 1, 2 and 5
(C) 1, 2, 4 and 6
(D) 3 and 5 only
Distinguish between esterfication and saponification reaction with the help of the chemical equations for each.
Mention the essential material (chemicals) to prepare soap in the laboratory. Describe in brief the test of determining the nature (acidic/alkaline) of the reaction mixture of saponification reaction.
What is the advantage of detergents over soaps for washing clothes? Also state one disadvantage.
Which one of the following sets of materials can be used to prepare soap?
(A) Neem oil and calcium hydroxide
(B) Castor oil and sodium hydroxide
(C) Mineral oil and sodium hydroxide
(D) Neem oil and magnesium hydroxide
A student is testing water to know which is best for cleansing purposes with soaps. He would find that the cleansing action of soaps is best when he uses water obtained from
(a) rain
(b) tap
(c) hand pump
(d) pond
Distinguish between esterification and saponification reactions of organic compounds.
Give a scientific explanation.
Soap forms a precipitate in hard water.
Explain why soap cannot be used in hard water.
Soaps are ester of which type of acids?
