Question

use the observation in the first column to answer the question in the second column.

observation	question
at 1 atm pressure, substance e boils at 7. °c and substance f boils at 27. °c.	which has a higher enthalpy of vaporization?<br>substance e<br>substance f<br>neither, e and f have the same enthalpy of vaporization.<br>its impossible to know without more information.
the enthalpy of vaporization of substance a is smaller than that of substance b.	at any temperature where both substances are liquid, which has the higher vapor pressure?<br>substance a<br>substance b<br>neither, a and b have the same vapor pressure.<br>its impossible to know without more information.

Explanation:

Step1: Recall vapor - pressure and boiling - point relationship

Lower vapor pressure at a given temperature means higher boiling point. At 9 °C, Substance D has lower vapor pressure (73 torr) than Substance C (93 torr). So Substance D has a higher boiling point.

Step2: Recall boiling - point and enthalpy of vaporization relationship

Higher boiling point generally means higher enthalpy of vaporization. At 1 atm, Substance F boils at a higher temperature (27 °C) than Substance E (7 °C), so Substance F has a higher enthalpy of vaporization.

Step3: Recall enthalpy of vaporization and vapor - pressure relationship

A substance with a lower enthalpy of vaporization has higher vapor pressure at the same temperature when both are liquid. Since the enthalpy of vaporization of Substance A is smaller than that of Substance B, Substance A has higher vapor pressure.

Answer:

Substance D
Substance F
Substance A