Question

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

observation	question
the enthalpy of vaporization of substance c is smaller than that of substance d.	at any temperature where both substances are liquid, which has the higher vapor pressure?<br>substance c<br>substance d<br>neither, c and d have the same vapor pressure.<br>its impossible to know without more information.
at - 8 °c, substance e has a vapor pressure of 139. torr and substance f has a vapor pressure of 189. torr.	which has a higher boiling point?<br>substance e<br>substance f<br>neither, e and f have the same boiling point.<br>its impossible to know without more information.

Explanation:

Step1: Recall boiling - point and vapor - pressure relationship

Lower boiling - point substances have higher vapor pressures at a given temperature. Substance A boils at 93 °C and Substance B boils at 133 °C. So Substance A has a higher vapor pressure.

Step2: Recall enthalpy of vaporization and vapor - pressure relationship

A smaller enthalpy of vaporization means it is easier for the substance to vaporize. Substance C has a smaller enthalpy of vaporization than Substance D, so Substance C has a higher vapor pressure at the same temperature when both are liquid.

Step3: Recall vapor - pressure and boiling - point relationship

Higher vapor pressure at a given temperature corresponds to a lower boiling - point. Substance E has a vapor pressure of 139 torr and Substance F has a vapor pressure of 189 torr at - 8 °C. So Substance E has a higher boiling - point.

Answer:

1. Substance A
2. Substance C
3. Substance E