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Question
Explain why soap cannot be used in hard water.
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Solution
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.
RELATED QUESTIONS
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
Explain the formation of scum when hard water is treated with soap.
A student took four test tubes P, Q, R and S and filled about 8 mL of distilled water in each. After that he dissolved an equal amount of Na2SO4 in P, K2SO4 in Q, CaSO4 in R and MgSO4 in S. On adding an equal amount of soap solution and shaking each test tube well, a good amount of lather will be obtained in the test tubes:
(a) P and Q
(b) P and R
(c) P, Q and S
(d) Q, R and S
Distinguish between esterfication and saponification reaction with the help of the chemical equations for each.
What are the raw materials required for making soap in a laboratory (or at home)?
Give the reason of formation of scum when soaps are used with hard water.
What is a soap?
Explain the action of soap in removing an oily spot from a piece of cloth.
Match the following
| 1. | Soap | C6H5 OH |
| 2. | Cement | CaSO4.2H2O |
| 3. | Fertilizers | NaOH |
| 4. | Gypsum | RCC |
| 5. | Phenol | NPK |
Arrange the following statements in correct sequence
- Pour that solution into an empty matchbox, soap can be obtained after drying.
- Take the necessary quantity of water in a jar.
- Then add coconut oil drop by drop and stir it well.
- Add concentrated sodium hydroxide in the jar and allow it to cool.
- Try this soap to wash your hand kerchief.
- Cover your work area with old newspaper.
