Question

4.) Calculate the vapor pressure of a solution made by mixing 32.3g of CaCl2, 90 g of C6H12O6 in 750g of H2O at a temperature of 41°C. The vapor pressure of H2O at 41°C is 58.2 torr.

Answer 1

$$P_{solution} = \chi_{solvent}P_{solvent}$$

$$\chi_{solvent} = {n_{water} \over n(CaCl_2)+n(C_6H_{12}O_6)+n_{water}}$$

$$n_{water} = 750g/18.0g/mol = 41.67mol$$

$$n(CaCl_2) = 32.3g/111.0g/mol = 0.29mol$$

$$n(C_6H_{12}O_6) = 90.0g/180g/mol = 0.50 mol$$

$$\chi_{water} = {41.67 \over 41.67 + 0.29 + 0.50} = 0.98$$

$$P_{solution} = 0.98*58.2 torr = 57.036 torr$$