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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
When you add about 2 ml of acetic acid to a test tube containing an equal amount of distilled water and leave the test tube to settle after shaking its contents, what will you observe in the test tube after about 5 minutes?
(A) A white precipitate settling at its bottom
(B) A clear colourless solution
(C) A layer of water over the layer of acetic acid
(D) A layer of acetic acid over the layer of water
In order to study saponification reaction, we first prepare 20% solution of sodium hydroxide. If we record the temperature of this solution just after adding sodium hydroxide flakes to water and also test its nature using litmus, it may be concluded that the process of making this solution is
(A) exothermic and the solution is alkaline
(B) endothermic and the solution is alkaline
(C) endothermic and the solution is acidic
(D) exothermic and the solution is acidic
When you add a few drops of acetic acid to a test-tube containing sodium bicarbonate powder, which one of the following is your observation?
(A) No reaction takes place
(B) A colourless gas with pungent smell is released with brisk effervescence
(C) A brown coloured gas is released with brisk effervescence
(D) Formation of bubbles of a colourless and odourless gas
Give the common name and IUPAC name of C2H5OH.
A neutral organic compound is warmed with some ethanoic acid and a little of conc. H2SO4. Vapours having sweet smell (fruity smell) are evolved. What type of functional group is present in this organic compound?
What is glacial acetic acid?
State how the following conversion can be carried out:
Ethyl chloride to Ethene.
State are relevant observations for following reactant:
Addition of ethyl alcohol to acetic acid in presence of conc. H2SO4
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.
Draw the structural diagram of:
Ethanoic acid
