Benzene and toluene form an ideal solution. The vapour pressures of benzene and toluene are 75 mm and 25 mm, respectively, at 20°C. If the mole fractions of benzene and toluene in vapour are 0.75 and

Question

Benzene and toluene form an ideal solution. The vapour pressures of benzene and toluene are 75 mm and 25 mm, respectively, at 20°C. If the mole fractions of benzene and toluene in vapour are 0.75 and 0.25, respectively, the vapour pressure of the ideal solution is:

Prashant Kotian · Accepted Answer

Correct answer: B. In the vapour phase, Dalton's law and Raoult's law give: Y_A = P_A / P_total = (P_A^o * X_A) / P_total. We can write: 1 / P_total = Y_benzene / P_benzene^o + Y_toluene / P_toluene^o. Substituting the given values: 1 / P_total = 0.75 / 75 + 0.25 / 25 = 0.01 + 0.01 = 0.02. Therefore, P_total = 1 / 0.02 = 50 mm.

💡 Solution & Explanation

Practice 22,000+ questions like this