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प्रश्न
Consider the following comments about saponification reactions:
I. Heat is evolved in these reactions.
II. For quick precipitation of soap, sodium chloride is added to the reaction mixtures.
III. Saponification reactions are a special kind of neutralisation reactions.
IV. Soaps are basic salts of long-chain fatty acids.
The correct comments are
(a) I, II and III
(b) II, III and IV
(c) I, II and IV
(d) Only I and IV
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उत्तर
Soaps are sodium or potassium salts of long-chain fatty acids. Since sodium and potassium hydroxides are bases, their solutions in water are alkaline.
Dissolution of sodium or potassium hydroxide in water evolves a large amount of heat. Thus, saponification reactions are exothermic in nature.
Common salt is added in a saponification reaction, as it helps in the precipitation of a soap by decreasing the solubility of the soap.
Thus, statements I, II and IV are correct.
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संबंधित प्रश्न
A student puts a drop of reaction mixture of a saponification reaction first a blue litmus paper and then on a red litmus paper. He may observe that:
(a) There is no change in the blue litmus paper and the red litmus paper turns white.
(b) There is no change in the red litmus paper and the blue litmus paper turns red.
(c) There is no change in the blue litmus paper and the red litmus paper turns blue.
(d) No change in colour is observed in both the litmus papers
A student adds a few drops of ethanoic acid to test tubes X, Y and Z containing aqueous solutions of sodium chloride, sodium hydroxide and sodium carbonate, respectively. If he now brings a burning splinter near the mouth of the test tubes immediately after adding ethanoic acid in each one of them, in which of the test tube or test tubes the flame will be extinguished?
(A) X and Y
(B) Y and Z
(C) X and Z
(D) only Z
What is the common name of methanoic acid.
An organic acid X is a liquid, which often freezes during winter time in cold countries, having the molecular formula C2H4O2. On warming it with methanol in the presence of a few drops of concentrated sulphuric acid, a compound Y with a sweet smell is formed.
(a) Identify X and Y. Also write their formulae showing the functional group present in them.
(b) Write a chemical equation for the reaction involved.
What do you notice when acetic acid reacts with metals?
Name the substance used to change acetic acid to acetic anhydride?
Name the functional group present in the following compound:
C2H5CHO
Choose the correct option from given alternative:
When sodium hydrogen carbonate is added to ethanoic acid a gas evolves. Consider the following statements about the gas evolved?
(A) It turns lime water milky.
(B) It is evolved with brisk effervescence.
(C) It has a smell of burning sulfur.
(D) It is also a by-product of respiration.
Give the balanced chemical equation of the following reaction:
Neutralization of NaOH with ethanoic acid.
Give the balanced chemical equation of the following reaction:
Neutralization of NaOH with ethanoic acid.
