Question

Does the nature of intermolecular forces change when a substance goes from a solid to a liquid or from a liquid to a gas? What causes a substance to undergo a phase change?

Short answer

Yes, the nature of intermolecular forces changes when a substance changes from solid to liquid or from liquid to gas.

Step-by-step solution

Intermolecular forces

The name intermolecular forces represents the attraction that exists between the molecules of a substance. They vary with the temperature and pressure.

Changes in intramolecular forces

When a substance changes its phase from solid to liquid, the distance between the molecules increases, and it leads to a decrease in intermolecular attractions.

When a substance changes its phase from liquid to gaseous state, then the distance between the molecules increases, and it leads to a decrease in intermolecular attractions.

The decrease in intermolecular forces will lead to the phase change of a substance from solid to liquid and liquid to gas.