Question

Which of these molecules would you expect to have the lowest boiling point? Select the single best answer.
Chloromethane?
Methylamine?
Trichloromethane?

Answer 1

To determine which molecule has the lowest boiling point among chloromethane, methylamine, and trichloromethane, we need to consider the intermolecular forces present in each molecule.

1. **Chloromethane (CH3Cl)**: This molecule exhibits dipole-dipole interactions due to the presence of a polar C-Cl bond, as well as London dispersion forces.

2. **Methylamine (CH3NH2)**: Methylamine can form hydrogen bonds due to the presence of the nitrogen atom bonded to a hydrogen atom. Hydrogen bonding typically leads to higher boiling points compared to dipole-dipole interactions.

3. **Trichloromethane (CHCl3)**: This molecule, while it also has dipole-dipole interactions from its polar C-Cl bonds, is bulkier and more polarizable than chloromethane due to the presence of three chlorine atoms, resulting in stronger intermolecular interactions than chloromethane.

Considering these points, methylamine would likely have the highest boiling point due to hydrogen bonding, while trichloromethane would have a higher boiling point than chloromethane due to increased dipole-dipole interactions and polarizability.

Thus, the molecule you would expect to have the lowest boiling point is **Chloromethane (CH3Cl)**.