When a sample of a gas is heated, the kinetic energy of the particles that make up the gas increases. This increase in kinetic energy causes the particles to move more rapidly and collide with each other and the walls of the container more frequently and with more force. As a result, the volume of the gas may expand, and the pressure of the gas may increase. Additionally, the individual particles may also gain enough energy to overcome intermolecular forces and transition into a different phase, such as from a gas to a liquid or a solid.
