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?

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Answer 1 · 2017-02-15T16:34:41

#23.6mmHg#

Use Raoults Law

# p_{i}=p_{i}^{\star }x_{i},#

#" Calculate number of moles in each of the substance"#

#"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"#

Now calculate vapour pressure

#"Mole fraction H2O = 13.9 mol H_2O/(0.12 mol+ 13.9 mol) = 0.991"#

#"Partial pressure of soln = 0.991 * 23.76 = 23.546 mm Hg"#