Question

Calculate the vapor pressure of a solution made by dissolving 109 grams of glucose (molar mass = 180.2 g/mol in 920.0 ml of water at 25 °c. the vapor pressure of pure water at 25 °c is 23.76 mm hg. assume the density of the solution is 1.00 g/ml.

Answer 1

Given data: molar mass = 180.2 g/mol in 920.0 ml of water at 25 °c.
                   the vapor pressure of pure water at 25 °c is 23.76 mm hg. 
Asked: the vapor pressure of a solution made by dissolving 109 grams of glucose

Solution:
moles glucose = 109 g/ 180.2 g/mol=0.605 
mass water = 920 mL x 1 g/mL = 920 g 
moles water = 920 g/ 18.02 g/mol=51.1 
mole fraction water = 51.1 / 51.1 + 0.605 =0.988 
vapor pressure solution = 0.988 x 23.76 = 23.47 mm Hg