Question

The types of intermolecular forces in a substance are identical whether it is a solid, a liquid, or a gas. Why then does a substance change phase from a gas to a liquid or to a solid?

Short answer

The kinetic energy is responsible for the change in the phase of a substance.

Step-by-step solution

Definition of Solid

The solid state is a fundamental state of matter. The molecules of a solid are densely packed and have the least amount of kinetic energy.The structural rigidity of a solid, as well as its resistance to a force applied to its surface, are its distinguishing features.

Explanation for the phase transition

The fact that a kinetic energy is greater or lesser than the attractive forces acting between the particles of a substance and determines the phase transition.

If the kinetic energy of a gas is equal to or less than the attraction forces in the gas, it will condense into a liquid.

Similarly, if the kinetic energy falls below the threshold required to overcome a solid's attractive forces, a liquid will solidify.