Which of the following statements about the composition of the vapour over an ideal `1:1` mol mixture of benzene and toluene is correct? Assume that the temperature is constant at `25^(@)C`. (Given: vapour pressure Date at `25^(@)C`, benzene=12.8 kP, toluene=3.85 kPa)

Options

A. The vapour will contain equal amounts of benzene and toluene
B. Not enough information is given to make a prediction
C. The vapour will contain a higher percentage of benzene
D. The vapour will contain a higher percentage of toluene

Answer

C

Explanation

`P_("Benzene")=x_("Benzene")xxP_("Benzene")^(@)`
`P_("Toluene")=x_("Toluene")xxP_("Toluene")^(@)`
For an ideal `1:1` mixture of benzene and toluene
`x_("Benzene")=(1)/(2),x_("Toluene")=(1)/(2)`
`P_("Benzene")=(1)/(2)xxP_("Benzene")^(@)=(1)/(2)xx12.8"k Pa = 6.4 k Pa"`
`P_("Toluene")=(1)/(2)xxP_("Toluene")^(@)=(1)/(2)xx3.85" k Pa = 1.925 k Pa"`
Thus, the vapour will contain higher percentage of benzene as the partial vapour pressure of benzene is higher than that of toluene.