Which statement about the composition of vapour over an ideal 1:1 molar mixture of benzene and toluene is correct? Assume the temperature is constant at `25^@C.`
Benzene 75 mm Hg
Toluene 22 mm Hg

Options

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

Answer

A

Explanation

A: Benzene B: Toluene
`p= p_(A) + p_(B), p= p_(A)^(@) x_(A) + p_(B)^(@) x_(B)`
`=75 xx (1)/(2) + 22 xx (1)/(2) = 37.5 +11= 48.5`
Mole fraction of benzene in vapour, `y_(A)= (p_(A))/(p)= (37.5)/(48.5)= 0.78`
Mole fraction of toluene in vapour `y_(B)= 0.22 therefore` The vapour will contain higher percentage of benzene