A quantity of 75.2 g of phenol is dissolved in a solvent of . If the depression in freezing point is — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

*Assuming 1 kg of solvent is used.* Moles of phenol ($C_6H_5OH$, M=94 g/mol) $= 75.2 / 94 = 0.8 \text{ mol}$. Molality $m = 0.8 \text{ m}$. Using $\Delta T_f = i \times K_f \times m \implies 7 = i \times 14 \times 0.8 \implies 7 = i \times 11.2 \implies i = 7 / 11.2 = 0.625$. For dimerization, $i = 1 - \alpha/2 \implies 0.625 = 1 - \alpha/2 \implies \alpha/2 = 0.375 \implies \alpha = 0.75$. The percentage dimerization is 75%. Therefore, correct answer is 0075.