Question

The vapor pressure of liquid pentane, C5H12, is 40.0 mm Hg at 244 K. A sample of C5H12 is placed in a closed, evacuated container of constant volume at a temperature of 409 K. It is found that all of the C5H12 is in the vapor phase and that the pressure is 62.0 mm Hg. If the temperature in the container is reduced to 244 K, which of the following statements are correct?

a. No condensation will occur.
b. The pressure in the container will be 100. mm Hg.
c. Only pentane vapor will be present.
d. Some of the vapor initially present will condense.
e. Liquid pentane will be present.

Answer 1

The correct statements are that no condensation will occur when the temperature is reduced, and the vapor pressure of pentane will decrease resulting in the condensation of some of the initially present vapor.

Step-by-step explanation:

When a liquid is placed in a closed container and heated, more molecules escape the liquid and enter the vapor phase, increasing pressure. This is known as evaporation. The vapor pressure of a liquid is the pressure exerted by its vapor above the liquid. In this case, the vapor pressure of liquid pentane is 40.0 mm Hg at 244 K.

When the temperature in the container is increased to 409 K, all of the pentane is in the vapor phase and the pressure is 62.0 mm Hg. This means that some of the liquid pentane has evaporated and the vapor pressure has increased.

If the temperature is then reduced back to 244 K, the vapor pressure of pentane will decrease and some of the vapor initially present will condense back into a liquid. So, the correct statements are:

• No condensation will occur.

Answer 2

b. The pressure in the container will be 100mm Hg.

d. Some of vapor initially present will condense.

Step-by-step explanation:

The vapor pressure of liquid Pantene rises when there is container where evacuation of water molecules is restricted. The pressure inside the container rises to 100 mm Hg and then liquid molecules start condensing. These molecule form vapors.