Chapter 11, Problem 70E

The vapor pressures of several solutions of water-propanol (CH₃CH₂CH₂OH) were determined at various compositions, with the following data collected at 45°C:

${\chi }_{{\text{H}}_{\text{2}}\text{O}}$	Vapor pressure(torr)
0	74.0
0.15	77.3
0.37	80.2
0.54	81.6
0.69	80.6
0.83	78.2
1.00	71.9

a. Are solutions of water and propanol ideal? Explain.

b. Predict the sign of ∆H_soln for water-propanol solutions.

c. Are the interactive forces between propanol and water molecules weaker than, stronger than, or equal to the interactive forces between the pure substances? Explain.

d. Which of the solutions in the data would have the lowest normal boiling point?