Use the observation in the first column Observation Questions
At 4 °C, Substance E has a Which has a higher boiling point
vapor pressure of 86. torr and Substance A. Substance E
F has a vapor pressure of 136. torr. B. Substance F
C. Neither, E and F have the
same boiling point.
The enthalpy of vaporization of Substance At any temperature where both
C is smaller than that of Substance D. substances are liquid which has
has the higher vapor pressure?
A. Substance C
B. Substance D
C. Neither, C and D have the
same vapor pressure
Which has a higher vapor pressure?
At 1 atm pressure Substance A boils at A. Substance A
129. °C and Substance B B. Substance B
boils at 154. °C. C. Neither, A and B have the
same vapor pressure.

A. Substance E

A. Substance C

A. Substance A  

Explanation:

Given that:

At 4 °C, Substance E has a vapor pressure of 86. torr and Substance F has a vapor pressure of 136. torr

Which has a higher boiling point?

A. Substance E

B. Substance F

C. Neither,EandF have the same boiling point

The vapor pressure varies inversely proportional to the boiling point.

Therefore, the lower the vapor pressure, the higher the boiling point.

At 4°C, Substance E with a lower vapor pressure of 86. torr will have a higher boiling point from the given information.

2.

Recall that :

therefore, the lower the enthalpy of vaporization, the higher the vapor pressure at any given temperature.

Given that:

Substance C has an enthalpy of vaporization smaller than that of substance D. Then, substance C has a higher vapor pressure.

3.

We've earlier said that:

The vapor pressure varies inversely proportional to the boiling point.

Therefore, the lower the vapor pressure, the higher the boiling point.

As such, Substance A will have a higher boiling point.