[slu1986]

A solution is prepared by dissolving 40.0 g of sucrose, C12H22O11, in 250 g of water at 25 C.  What is the vapor pressure of the solution if the vapor pressure of water at 25 C is 23.76 mm Hg?

A) 0.198 mm Hg
B) 20.5 mm Hg
C) 23.6 mm Hg
D) 24.0 mm Hg

This is how I worked the problem:

Mol of H20 = 250 g H2O * 1 mol/18.02 g H2O = 13.9 mol H2O

Mol C12H22O11 = 40.0 g C12H22O11 * 1 mol/342.296 g = 0.12 mol sucrose

Mole fraction H2O = 13.9 mol H2O/0.12 mol+ 13.9 mol = 0.991

P soln = 0.991 * 23.76 = 23.546 mm Hg<-----this is what i got for the answer, but I don't know if it is right..the closest answer in the choices to this one is 23.6 mm Hg..Could someone tell me if I got this right or wrong...if wrong please tell me what I did wrong.  Thanks

[Borek]

OK