Chapter 13, Problem 108AP

A 1.32-g sample of a mixture of cyclohexane $\left({\text{C}}_{\text{6}}{\text{H}}_{\text{12}}\right)$ and naphthalene $\left({\text{Cl}}_{\text{10}}{\text{H}}_{\text{8}}\right)$ is dissolved in 18.9 g of benzene $\left({\text{C}}_{\text{6}}{\text{H}}_{\text{6}}\right)$. The freezing point of the solution is $\text{2}\text{.2°C}$. Calculate the mass percent of the mixture. (See Table 13.2 for constants.)

TABLE 13.2Molal Boiling-Point Elevation and Freezing-Point Depression Constants of Several Common Solvents

Solvent	Normal Boiling Point $\left(\text{ºC}\right)$	$K_b\left(°C/m\right)$	Normal Freezing Point $\left(ºC\right)$	$K_f\left(°C/m\right)$
Water	100.0	0.52	0.0	1.86
Benzene	80.1	2.53	5.5	512
Ethanol	78.4	1.22	-117.3	1.99
Acetic acid	117.9	2.93	16.6	3.90
Cyclohexane	80.7	2.79	6.6	20.0