The vapor pressure of pure water at 65^oC is 412 torr.

What is the vapor pressure at 65^oC of a solution prepared from 100 mL of water (density 1.00 g/mL) and 120 g of diglyme, C₆H₁₄O₃, a nonvolatile substance?

Question

The vapor pressure of pure water at 65^oC is 412 torr.

What is the vapor pressure at 65^oC of a solution prepared from 100 mL of water (density 1.00 g/mL) and 120 g of diglyme, C₆H₁₄O₃, a nonvolatile substance?

| General Chemistry 2

Accepted Answer

Raoult’s Law:

P_water = x_water P⁰_water

P_water = vapor pressure of the water in the solution

x_water = mole fraction of water in the solution

P⁰_water = vapor pressure of the pure water

x_water = $\frac{n_{water}}{n_{water} + n_{diglyme}}$

n_water =

\frac{m_{water}}{M_{water}}

=

\frac{100}{18.0}

= 5.55 mol

n_diglyme =

\frac{m_{diglyme}}{M_{diglyme}}

=

\frac{120}{134.17}

= 0.894 mol

x_water =

\frac{5.55}{6.45}

= 0.861

P_water = x_water P⁰_water = 0.861 x 412 = 355 torr

Exercise 6 | Colligative Properties of Solutions

General Chemistry 2 - Exercise 6