In each pair of compounds, pick the one with the higher boiling point. Explain your reasoning. a. CH₃OH or CH₃SH b. CH₃OCH₃ or CH₃CH₂OH

Verified step by step guidance

1. Identify the types of intermolecular forces present in each compound. For example, CH₃OH has hydrogen bonding, while CH₃SH has dipole-dipole interactions and London dispersion forces.
2. Recall that hydrogen bonding is generally stronger than dipole-dipole interactions and London dispersion forces, leading to higher boiling points.
3. Compare the molecular structures of CH₃OH and CH₃SH. Note that CH₃OH can form hydrogen bonds due to the presence of an -OH group, whereas CH₃SH cannot form hydrogen bonds as effectively because it has an -SH group.
4. For the second pair, CH₃OCH₃ (dimethyl ether) has dipole-dipole interactions and London dispersion forces, while CH₃CH₂OH (ethanol) can form hydrogen bonds due to its -OH group.
5. Conclude that compounds with hydrogen bonding, such as CH₃OH and CH₃CH₂OH, typically have higher boiling points than those with only dipole-dipole interactions and London dispersion forces.

Key Concepts

Hydrogen Bonding

Hydrogen bonding is a strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like oxygen, nitrogen, or fluorine. This interaction significantly increases the boiling point of compounds because more energy is required to break these bonds during the phase transition from liquid to gas.

Molecular Polarity

Molecular polarity refers to the distribution of electrical charge over the atoms in a molecule. Polar molecules, which have an uneven distribution of charge, tend to have higher boiling points than nonpolar molecules due to stronger intermolecular forces, such as dipole-dipole interactions and hydrogen bonding.

Molecular Weight

Molecular weight, or molar mass, is the mass of a molecule calculated by adding the atomic masses of its constituent atoms. Generally, compounds with higher molecular weights have higher boiling points due to increased van der Waals forces, which are the weak attractions between molecules that become more significant as the size of the molecules increases.