Question

Explain why each molecule has a higher boiling point than the other in the pair.

Match the words in the left column to the appropriate blanks in the sentences on the right. Make certain each sentence is complete before submitting your answer.

- The main reason that NO₂ has a higher boiling point than CO₂ is that NO₂ ______
- The main reason that NH₃ has a higher boiling point than CH₄ is that NH₃ ______
- The main reason that CS₂ has a higher boiling point than CO₂ is that CS₂ ______

1. Exhibits dispersion forces
2. Has a larger molar mass
3. Exhibits ion-dipole forces
4. Exhibits dipole-dipole forces
5. Exhibits hydrogen bonding

Answer 1

A molecule that exhibits hydrogen bonding has a higher boiling point compared to one that only exhibits dispersion forces because hydrogen bonds are much stronger intermolecular forces than dispersion forces.

Step-by-step explanation:

The boiling point of a substance is indicative of the strength of the intermolecular forces (IMFs) present within it. Dispersion forces, also known as London forces, occur in all atoms and molecules as a result of instantaneous fluctuations in the electron distribution that induce temporary dipoles. These are the weakest form of IMFs and generally increase with the size of the atom or molecule as a greater number of electrons leads to larger fluctuations.

Hydrogen bonding is a stronger IMF that occurs when a hydrogen atom is bonded to a highly electronegative atom such as nitrogen, oxygen, or fluorine. This causes a significant dipole where the hydrogen develops a partial positive charge and can thus interact strongly with electronegative atoms in adjacent molecules. This interaction is so strong that it results in a much higher boiling point for substances with hydrogen bonds when compared to those with just dispersion forces.