Question

The molecular weight of benzoic acid in benzene as determined by depression in the freezing point method corresponds to

• A. Solvation of benzoic acid
• B. Ionization of benzoic acid
• C. Dimerisation of benzoic acid
• D. Trimerisation of benzoic acid.

Answer 1

The correct option is C

Dimerisation of benzoic acid

Explanation for correct option:

(c) Dimerisation of benzoic acid

• By using the depression in freezing point approach, it is discovered that benzoic acid has a molecular weight of $244$.
• The exact mass of the benzoic acid molecule is $122$.
• As a result, it is equivalent to the dimers created through hydrogen bonding.

• Hence this is the correct option.

Explanation for incorrect options:

(a) Solvation of benzoic acid

• The molecular weight of benzoic acid in benzene is determined by depression in the freezing point method.

(b) Ionization of benzoic acid

• Benzoic acid does not ionize as it is covalent in nature

(d) Trimerisation of benzoic acid.

• Dimerization occurs in benzoic acid, not trimerization
• Hence this is the incorrect option.

So, option (c) Dimerisation of benzoic acid is the correct answer.