A sample of octane in equilibrium with its vapor in a closed 1.0-L container has a vapor pressure of 50.0 torr at 45$\degree$C. The container's volume is increased to 2.0 L at constant temperature and the liquid/vapor equilibrium is reestablished. What is the vapor pressure?
A) 50.0 torr
B) 50.0 torr
C) 25.0 torr
D) The mass of the octane vapor is needed to calculate the vapor pressure.
E) The external pressure is needed to calculate the vapor pressure.

Question

A sample of octane in equilibrium with its vapor in a closed 1.0-L container has a vapor pressure of 50.0 torr at 45$\degree$C. The container's volume is increased to 2.0 L at constant temperature and the liquid/vapor equilibrium is reestablished. What is the vapor pressure?
A) > 50.0 torr
B) 50.0 torr
C) 25.0 torr
D) The mass of the octane vapor is needed to calculate the vapor pressure.
E) The external pressure is needed to calculate the vapor pressure.

Quizplus · Accepted Answer

The vapor pressure of a liquid in equilibrium with its vapor is determined by the temperature alone, not by the volume of the container. Since the temperature remains constant at 45°C, the vapor pressure remains 50.0 torr.

A Sample of Octane in Equilibrium with Its Vapor in a Closed