Question

Based on molecular mass and dipole moment of the five compounds in the table below, which should have the highest boiling point? Explain the answer.

A) CH3CH2CH3
B) CH3OCH3
C) CH3Cl
D)CH3CHO
E) CH3CN

Answer 1

Considering their similar molecular masses, the compound with the stronger dipole moment will have a higher boiling point; thus, CH3CHO, with a polar C=O bond, most likely has the highest boiling point.

Step-by-step explanation:

To determine which compound among CH3CH2CH3, CH3OCH3, CH3Cl, CH3CHO, and CH3CN should have the highest boiling point, we need to consider molecular mass and dipole moment. All these compounds have similar molar masses, thus the difference in boiling points will largely be attributed to differences in polarity and the types of intermolecular forces they experience.

Compounds with higher polarity exhibit stronger dipole-dipole interactions, and since acetone (CH3CHO) contains a polar C=O double bond, it should experience stronger dipole-dipole interactions compared to the others. Moreover, nitriles (CH3CN) have strong dipole-dipole interactions and potential hydrogen bonding abilities, which might suggest an even higher boiling point. However, the lack of multiple polar bonds or a stronger dipole might limit this effect. Therefore, based on the provided information, we would predict that CH3CHO, due to its significant dipole moment contributed by the C=O bond, should have the highest boiling point.