At `70^@C` vapour pressure of pure benezene and pure toluene are 500 torr and 200 torr, respectively. In a homogeneous mixture of toluene with benzene at `70^@C`, the mole fraction of benezene is 0.4. Calculate the vapour pressure of the mixture.

Explanation

Vapour pressure of the mixture (p) is the sum of the total partial pressures of the components.
`p=p_1X_1+p_2X_2`=500 x 0.4 + 200 x 0.6
Vapour pressure of mixture 200 + 120 = 320 torr