Vapor pressure question ?

Question

What is the vapor pressure over a 30 degree C water solution containing 652 g of sucrose, C12H22O11, per liter of solution? (Assume the solution behaves ideally. The vapor pressure over pure water at this temperature is 31.8 torr. Sucrose is nonvolatile. The density of the solution is 1.61 g/mL).

Please explain how to calculate this. Also, why is the information provided in the parenthesis important to this problem? Thanks!

Answer 1

Moles Sucrose = 652 g / 342.29648 g/mol = 1.90

Mass solution = 1.61 g/mL x 1000 mL = 1610 g

Mass water = 1610 - 652 = 958 g

Moles water = 958 g / 18.02 g/mol =53.2

Total moles = 1.90 + 53.2 = 55.1

Mole fraction water = 53.2 / 55.1 =0.966

p = p° X = 31.8 x 0.966 = 30.7 torr