Advertisements
Advertisements
Question
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
Advertisements
Solution
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.
APPEARS IN
RELATED QUESTIONS
What do you observe when you drop a few drops of acetic acid to test tubes containing
(a) phenolphthalein
(b) distilled water
(c) universal indicator
(d) sodium hydrogen carbonate powder
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 takes 2 mL acetic acid in a dry test tube and adds a pinch of sodium hydrogen carbonate to it. He makes the following observations:
I. A colourless and odourless gas evolves with a brisk effervescence.
II. The gas turns lime water milky when passed through it.
III. The gas burns with an explosion when a burning splinter is brought near it.
IV. The gas extinguishes the burning splinter that is brought near it.
The correct observations are:
(A) I, II, and III
(B) II, III and IV
(C) III, IV and I
(D) IV, I and II
Which one of the following are the correct observations about acetic acid?
(A) It turns blue litmus red and smells like vinegar
(B) It turns blue litmus red and smells like burning sulphur
(C) It turns res litmus blue and smells like vinegar
(D) It turns red litmus blue and has a fruity smell
Explain the following term with example.
Reduction
Draw the structural formula of a compound with two carbon atoms in the following case:
An alkane with a carbon to carbon single bond.
Using appropriate catalysts, ethane can be oxidized to an alcohol. Name the alcohol formed when ethane is oxidized.
Identify the term or substance based on the descriptions given below:
Hydrocarbon containing a triple bond used for welding purposes
Explain the following reaction with an example.
Esterification
What happens when a small piece of sodium is dropped in ethanol? Write the equation for this reaction.
