Question

Benzene and toluene form nearly ideal solutions. At 20°C, the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The parial vapour pressure of benzene at 20°C for a solution containing 78g of benzene and 46g of toluene in torr is.

• A. 50
• B. 25
• C. 37.5
• D. 53.5

Answer 1

Answer: (A)

50

Answer 2

P_B = $P _ { B } ^ { o } X _ { B }$ ; ∴ $P _ { B } = \frac { \frac { 78 } { 78 } } { \frac { 78 } { 78 } + \frac { 46 } { 92 } } \times 75$ ; ∴ P_B = 50 torr