What is the vapor pressure in Torr above a solution prepared by mixing 66.73g of benzene C6H6 with 63.26g toluene C6H5CH3 at 20 Celsius. The vapor pressure of pure benzene and toluene at 20celsius are 75 and 22 torr respectively. These compounds form nearly ideal solutions when mixed together.

Answer 1

toluene = T
benzene = B
moles T = grams/molar mass
moles B = grams/molar mass
mole fraction B = moles B/total moles.
mole fraction T = moles T/total moles.

PB = XB*P^o
PT = XT*P^o
Total pressure = PB + PT.