In each pair of compounds, pick the one with the higher boiling point. Explain your reasoning. c. CH₃OCH₃ or CH₃CH₃OH

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Identify the types of intermolecular forces present in each compound. CH_3OCH_3 (dimethyl ether) primarily exhibits dipole-dipole interactions and London dispersion forces, while CH_3CH_2OH (ethanol) exhibits hydrogen bonding, dipole-dipole interactions, and London dispersion forces.

Understand that hydrogen bonding is a stronger intermolecular force compared to dipole-dipole interactions and London dispersion forces. This means that compounds capable of hydrogen bonding typically have higher boiling points.

Recognize that ethanol (CH_3CH_2OH) can form hydrogen bonds due to the presence of an -OH group, which is capable of forming strong hydrogen bonds with other ethanol molecules.

Acknowledge that dimethyl ether (CH_3OCH_3) lacks an -OH group and therefore cannot form hydrogen bonds, resulting in weaker intermolecular forces compared to ethanol.

Conclude that due to the presence of hydrogen bonding, ethanol (CH_3CH_2OH) will have a higher boiling point than dimethyl ether (CH_3OCH_3).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Intermolecular Forces

Intermolecular forces are the attractive forces between molecules that influence physical properties like boiling points. The main types include hydrogen bonding, dipole-dipole interactions, and London dispersion forces. Compounds with stronger intermolecular forces typically have higher boiling points because more energy is required to separate the molecules.

Hydrogen Bonding

Hydrogen bonding is a specific type of strong dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen, nitrogen, or fluorine. In the given compounds, CH3OH (methanol) can form hydrogen bonds due to the presence of an -OH group, significantly increasing its boiling point compared to compounds that cannot form such bonds.

Molecular Structure and Polarity

The molecular structure and polarity of a compound affect its boiling point. Polar molecules, which have an uneven distribution of charge, tend to have higher boiling points than nonpolar molecules due to stronger intermolecular attractions. In this case, CH3OCH3 (dimethyl ether) is less polar than CH3OH (methanol), leading to a lower boiling point for the former.