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प्रश्न
While studying saponification reaction for the preparation of soap, a teacher suggested to a student to add a small quantity of common salt to the reaction mixture. The function of common salt in this reaction is to
(A) reduce the alkalinity of the soap
(B) reduce the acidity of the soap
(C) enhance the cleansing capacity of soap
(D) favour precipitation of soap
उत्तर
Common salt is added in saponification reaction, as it helps in the precipitation of soap by decreasing the solubility of soap.
Hence, the correct option is D.
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संबंधित प्रश्न
When ethanol reacts with ethanoic acid in the presence of conc. H2SO4, a substance with fruity smell is produced. Answer the following:-
(i) State the class of compounds to which the fruity smelling compounds belong. Write the chemical equation for the reaction and write the chemical name of the product formed.
(ii) State the role of conc. H2SO4 in the reaction.
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
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
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
Esters are sweet-smelling substances and are used in making perfumes. Describe an activity for the preparation of an ester with the help of a well labelled diagram. Write an equation for the chemical reaction involved in the formation of the ester. Also write the names of all the substances involved in the process of esterification.
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.
Two statements are given - one labelled Assertion (A) and the other labelled Reason (R).
Assertion (A): Esterification is a process in which a sweet-smelling substance is produced.
Reason (R): When esters react with sodium hydroxide an alcohol and sodium salt of carboxylic acid are obtained.
Mineral acids are stronger acids than carboxylic acids because
- mineral acids are completely ionised
- carboxylic acids are completely ionised
- mineral acids are partially ionised
- carboxylic acids are partially ionised
Write the chemical equation for the ethanol to ethanoic acid of an oxidation reaction.
Give the balanced chemical equation of the following reaction:
Combustion of ethanol.
