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प्रश्न
Explain why soap cannot be used in hard water.
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उत्तर
Soaps cannot be used in hard water because they lose their cleansing property when used with it. Soaps do not form lather with hard water and instead form scum, as a result of which they lose their cleansing property.
संबंधित प्रश्न
While preparing soap a small quantity of common salt is generally added to the reaction mixture of vegetable oil and sodium hydroxide. Which one of the following may be the purpose of adding common salt?
(A) To reduce the basic nature of the soap
(B) To make the soap neutral
(C) To enhance the cleansing power of the soap
(D) To favour the precipitation of the soap
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
While studying the saponification reaction, what do you observe when you mix an equal amount of colourless vegetable oil and 20% aqueous solution of NaOH in a beaker?
(A) The colour of the mixture has become dark brown
(B) A brisk effervescence is taking place in the beaker
(C) The outer surface of the beaker has become hot
(D) The outer surface of the beaker has become cold
Which of the two is better for washing clothes when the water is hard: soap or detergent? Give reason for your answer.
Describe the structure of a soap molecule with the help of a diagram.
Differentiate between:
Detergents and Soaps.
Soap is a salt of ______ and sodium hydroxide.
Explain why often coloured spots are formed on clothes during washing.
Soaps were originally made from ______.
What are the two different types of molecules found in the soap?
