Which of the following statements about the composition of the vapour over an ideal 1:1 molar mixtur

Question

Which of the following statements about the composition of the vapour over an ideal 1:1 molar mixture of benzene and toluene is correct? Assume that the temperature is constant at $25^{\circ} \mathrm{C}$. (Given, vapour pressure data at $25^{\circ} \mathrm{C}$, benzene $=$ 12.8 kPa , toluene $=3.85 \mathrm{kPa}$ )\

Professor PC Thomas Classes · Answer

(c) $: p_{	ext {Benzene }}=x_{	ext {Benzene }} p^{\circ}{ }_{	ext {Benzene }}$\ $p_{	ext {Toluene }}=x_{	ext {Toluene }} p^{\circ}$ Toluene\ For an ideal 1:1 molar mixture of benzene and toluene,\ $x_{	ext {Benzene }}=\frac{1}{2}$ and $x_{	ext {Toluene }}=\frac{1}{2}$\ $p_{	ext {Benzene }}=\frac{1}{2} p_{	ext {Benzene }}^{\circ}=\frac{1}{2} 	imes 12.8 \mathrm{kPa}=6.4 \mathrm{kPa}$\ $p_{	ext {Toluene }}=\frac{1}{2} p_{	ext {Toluene }}^{\circ}=\frac{1}{2} 	imes 3.85 \mathrm{kPa}=1.925 \mathrm{kPa}$\ Thus, the vapour will contain a high percentage of benzene as the partial vapour pressure of benzene is higher as compared to that of toluene.\