# A solution is prepared by dissolving 40.0 g of sucrose, 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?

Feb 15, 2017

$23.6 m m H g$

#### Explanation:

Use Raoults Law

${p}_{i} = {p}_{i}^{\setminus \star} {x}_{i} ,$

$\text{ Calculate number of moles in each of the substance}$

$\text{Mol of H20 = 250 g H2O * 1 mol/18.02 g H2O = 13.9 mol H2O}$

$\text{Mol C12H22O11 = 40.0 g C12H22O11 * 1 mol/342.296 g = 0.12 mol sucrose}$

Now calculate vapour pressure

$\text{Mole fraction H2O = 13.9 mol H_2O/(0.12 mol+ 13.9 mol) = 0.991}$

$\text{Partial pressure of soln = 0.991 * 23.76 = 23.546 mm Hg}$