At 60° C, vapour pressure of methanol and water are 84.562 kPa and 19.953 kPa respectively. An aqueous solution of methanol at 60° C exerts a pressure of 39.223 kPa; the liquid phase and vapour phase mole fractions of methanol are 0.1686 and 0.5714 respectively. Activity co-efficient of methanol is__________________?

Question

Accepted Answer

1.572. The activity coefficient ($\gamma_1$) can be found using the formula: $P_{solution} = x_1 	ext{P}_1^* + x_2 	ext{P}_2^* \cdot \gamma_1$. Solving for $\gamma_1$ gives approximately 1.572.