What is the resulting vapor pressure?

Question

0.350 mol of a nonvolitile nonelectrolyte are dissolved in 3.10 mol of water. What is the resulting vapor pressure? The vapor pressure of pure water is 23.8 torr at 25 degrees C. (answer in torr)

A solution is composed of 1.55 mol cyclohexane ( P degrees = 97.6 torr) and 2.39 mol acetone ( P degrees= 229.5 torr). What is the total vapor pressure above this solution? (answer in torr)

Answer 1

3.10 mol /(0.35 + 3.10) = 0.8986 mol fraction

0.8986 x 23.8 = 21.4 torr

mol fraction cyclohexane = 1.55 / (1.55 + 2.39) = 0.393

mol fraction acetone = 2.39 / (1.55 + 2.39) = 0.607

P = 0.393x97.6 + 0.607x229.5 = 177.7 torr