Question

# The vapor pressure of liquid butanol, C4H9OH, is 100. mm Hg at 343 K. A sample...

The vapor pressure of liquid butanol, C4H9OH, is 100. mm Hg at 343 K.

A sample of C4H9OH is placed in a closed, evacuated 533 mL container at a temperature of 343 K. It is found that all of the C4H9OH is in the vapor phase and that the pressure is 48.0 mm Hg. If the volume of the container is reduced to 391 mL at constant temperature, which of the following statements are correct?

Choose all that apply.

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

Liquid butanol will be present.

Some of the vapor initially present will condense.

No condensation will occur.

Only butanol vapor will be present.

Correct statements are :

• No condensation will occur.

• Only butanol vapor will be present.

Explanation

According to Boyle's law, pressure is inversely proportional to volume

or, P1 * V1 = P2 * V2

where P1 = initial pressure = 48.0 mmHg

V1 = initial volume = 533 mL

P2 = final pressure

V2 = final volume = 391 mL

P2 = P1 * (V1 / V2)

P2 = 48.0 mmHg * (533 mL / 391 mL)

P2 = 48.0 mmHg * (1.363)

P2 = 65.4 mmHg

Since pressure is less than vapor pressure (100 mmHg), therefore condensation will not occur and only vapor will be present.