Question

Consider a solution containing liquids A and B where the mole fraction of B is 0.60. Assuming ideality, calculate the mole fraction of A in the vapor at equilibrium with this solution at 25°C. (The vapor pressures of pure liquid A and B at 25°C are 117.7 torr and 400.0 torr, respectively.)

A)	0.16
B)	196
C)	0.31
D)	3.40 ´ 10–3
E)	4.90 ´ 10–3

The freezing point (T_f) for t-butanol is 25.50°C and K_f is 9.1°C/m. Usually t-butanol absorbs water on exposure to the air. If the freezing point of a 12.9-g sample of t-butanol is measured as 24.59°C, how many grams of water are present in the sample?

A)	0.10 g
B)	0.023 g
C)	10. g
D)	2.3 g
E)	23 g

Answer 1