Calculate the volume of solution that has a vapour pressure of 31.27 mbar and contains 84.3g of sucrose, at a temperature of 25.0C. The vapour pressure of pure water at 25.0C is 31.7mbar, the density of water is 1.00g/mL, and assume no change in volume occurs upon dissolution.

Answer 1

P_soln = X_H2O*P^o_H2O
You know Psoln and PoH2O; solve for XH2O.
Then
XH2O = nH2O/(nH2O+nsucrose)
You know XH2O and nsucrose, solve for nH2O. Convert mols H2O to grams H2O then use density to convert to mL H2O.

Answer 2

n sucrose = grams sucrose/molar mass sucrose.