Which of the following would lower the vapor pressure of a sample of butanol in a closed container?

I) decreasing the temperature of the sample
II) decreasing the size of the container
III) draining off some of the liquid

a. I, II and III
b. I and II
c. II and III
d. I and III
e. II only
f. III only
g. I only

a yes, b no, c no.

I) Yes

II) No
III) No

So the answer is I only

To determine which option would lower the vapor pressure of a sample of butanol in a closed container, let's analyze each option:

I) Decreasing the temperature of the sample: Lowering the temperature reduces the average kinetic energy of the molecules, resulting in fewer molecules having enough energy to escape as vapor. Hence, decreasing the temperature would lower the vapor pressure.

II) Decreasing the size of the container: Decreasing the size of the container would increase the number of butanol molecules in a given volume, increasing the density of the liquid. Consequently, this would lead to more collisions between the butanol molecules, reducing the number of molecules that can escape and decreasing the vapor pressure.

III) Draining off some of the liquid: If we drain off some of the liquid, the number of butanol molecules in the container decreases. As a result, there are fewer molecules available to evaporate and contribute to the vapor pressure, causing a decrease in vapor pressure.

Combining the information from the analysis of each option, options I, II, and III would all lower the vapor pressure of a sample of butanol in a closed container. Therefore, the correct answer is a. I, II, and III.