Answer to Question #315052 in General Chemistry for Queen

Question

the vapor pressure of H2O at 28 degrees Celsius is 28.3mmhg find the vapor pressure of a solution containing 100g of sugar c12H22011 in 500g of H20 at 28 degrees celcius.

Answer 1

M(sugar, C₁₂H₂₂O₁₁) = 342 g/mole;

m(sugar, C₁₂H₂₂O₁₁) = 100 g;

M(H₂O) = 18 g/mole;

m(H₂O) = 500 g;

P₀ = 28.3mmHg;

n(sugar, C₁₂H₂₂O₁₁) = m(sugar, C₁₂H₂₂O₁₁)/M(sugar, C₁₂H₂₂O₁₁) = 100/342 = 0.29 moles;

n(H₂O) = m(H₂O)/M(H₂O) = 500/18 = 27.78 moles;

x_i = n(H₂O)/(n(H₂O) + n(sugar, C₁₂H₂₂O₁₁)) = 27.78/(27.78 + 0.29) = 27.78/28.07 = 0.9897

P_solution = x_i * P₀ = 0.9897 * 28.3 = 28.0 mmHg.

Answer: 28.0 mmHg.