Answer to Question #265344 in General Chemistry for Sunshine Jimenez

Question

The vapor pressure of pure water at 26°C is 25.2 torr. What is the vapor pressure of a solution which contains 20.0 g of glucose (C₆H₁₂O₆), in 70 g water?

Answer 1

Number of moles of glucose =20/180=0.111

Number of moles of water =70/18= 3.89

Mole fraction of glucose= 0.111/0.111+3.89=0.0278

The relative lowering in vapour pressure is equal to the mole fraction of solute.

25.21-p/25.21= 0.0278

P=25.21−(25.21×0.0278)=24.5 torr