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 bigger than that of substance d.	which has the higher boiling point?<br>substance c<br>substance d<br>neither, c and d have the same boiling point.<br>its impossible to know without more information.
at 78 °c, substance e has a vapor pressure of 97. torr and substance f has a vapor pressure of 77. torr.	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.

Explanation:

Step1: Recall boiling - point and enthalpy of vaporization relation

Higher boiling - point substances generally have stronger intermolecular forces and require more energy to vaporize, thus having a higher enthalpy of vaporization. Since Substance B boils at a higher temperature ($54^{\circ}C$) than Substance A ($16^{\circ}C$) at 1 atm, Substance B has a higher enthalpy of vaporization.

Step2: Analyze enthalpy of vaporization and boiling - point relation

Just because Substance C has a higher enthalpy of vaporization than Substance D doesn't directly tell us their boiling - point relationship without more information about the substances and their intermolecular forces. So it's impossible to know which has a higher boiling - point.

Step3: Recall vapor - pressure and enthalpy of vaporization relation

Lower vapor pressure at a given temperature indicates stronger intermolecular forces and a higher enthalpy of vaporization. Since Substance F has a lower vapor pressure (77 torr) than Substance E (97 torr) at $78^{\circ}C$, Substance F has a higher enthalpy of vaporization.

Answer:

1. Substance B
2. It's impossible to know without more information
3. Substance F