Question

a solution is 0.936 moles of benzoic acid (C7H6O2) dissolved in 4.832 moles acetone (C3H6O). Calculate the vapor pressue of the solution in a bttle that is in a room at 21.3 C. The vapor pressure of pure acetone at this temperature is 19450 torr.

Answer 1

moles of benzoic acid = 0.936

moles of acetone = 4.832

mole fraction of benzoic acid = 0.936 / (0.936 + 4.832)

                                              = 0.162

vapour pressure of pure acetone Po = 19450 torr

Po - Ps / Po = XB

19450 - Ps / 19450 = 0.162

Ps = 16294 torr

vapor pressue of the solution = 16294 torr