Question

A solution is composed of 1.40 mol cyclohexane (P∘cy=97.6 torr) and 2.10 mol acetone (P∘ac=229.5 torr). What is the total vapor pressure Ptotal above this solution?

Ptotal=177torr

As you saw in Part B, the vapor above the cyclohexane-acetone solution is composed of both cyclohexane vapor and acetone vapor. What mole fraction of the vapor above the solution, Xcy(vapor), is cyclohexane?

Answer 1

Answer:

Given,

To determine the total pressure

cyclohexane mole fraction = 1.40 / (1.40 + 2.10)

                                           = 0.4

acetone mole fraction = 2.10 / 1.40 + 2.10

                                    = 0.6

pratial pressure of cyclohexane is given as = mole fraction x pure state pressure

                                         = 0.4 x 97.6

                                         = 39.04 torr

partial pressure of acetone is given as = mole fraction x pure state pressure

                                             = 0.6 x 229.5

                                             = 137.7 torr

total pressure(Pt) = 39.04 torr + 137.7 torr

                        = 186.72 torr

                         = 176.74 torrr

= 177 torr

Hence Ptotal =177 torr