Answer to Question #302117 in General Chemistry for Hutchii

Question

Find the vapor pressure of a solution containing 35.0 g calcium chloride (CaCl2) in 750.0 g water. Note that P^0 water = 47.1 torr at 37.0 degrees C.

Answer 1

Solution:

Moles CaCl₂: 35.0 g / 110.98 g/mol = 0.315 mol

Moles H₂O: 750.0 g / 18.02 g/mol = 41.62 mol

Mole fraction H₂O: 41.62 / (3 x 0.315 + 41.62) = 0.9778

CaCl₂ = Ca²⁺ + 2Cl^- (i = 3, 3 ions)

The vapor pressure of the solution at 37⁰C:

0.9778 x 47.1 = 46.05 torr