Question

Benzoic acid dissolved in benzene shows a molecular mass of _______ g/mol.

• A. 122
• B. 244
• C. 366
• D. 488

Answer 1

The correct option is B

244

Benzoic acid:

• White solid that has the chemical formula ${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{CO}}_2\mathrm{H}$ is benzoic acid, which is the simplest aromatic carboxylic acid.
• The term comes from gum benzoin, which was the substance's exclusive source for a very long period.

Explanation of the correct answer:

The correct answer is option B:

1. Benzoic acid exists as a dimer in benzene.
2. Consequently, benzoic acid's molecular weight doubles.

$$\begin{gathered} {\left({\mathrm{C}}_6{\mathrm{H}}_5\mathrm{COOH}\right)}_2=2\times 122 \\ =244\mathrm{g}{\mathrm{mol}}^{-1} \end{gathered}$$

Hence, Benzoic acid dissolved in benzene shows a molecular mass of 244 g/mol.