The vapour pressure of pure liquid ‘A’ at 27°C is — Solutions and Colligative Properties Chemistry Question

💡 Solution & Explanation

Molar volume of liquid A ($V_{l,A}$) = $100 / 1.25 = 80 \text{ ml/mol} = 0.08 \text{ L/mol}$. Molar volume of vapour A ($V_{v,A}$) = $3800 \times 0.08 = 304 \text{ L/mol}$. Assuming ideal gas behavior for vapour: $P_A^\circ \cdot V_{v,A} = RT \implies P_A^\circ = (0.08 \times 300) / 304 = 24 / 304 \text{ atm} = (24 \times 760) / 304 \text{ torr} = 18240 / 304 = 60 \text{ torr}$. Therefore, correct answer is A.