What is the term for the heat required to change a substance from one state to another?

The term that describes the heat required to change a substance from one state to another is latent heat. This term specifically refers to the heat energy that is absorbed or released by a substance during a phase change, such as from solid to liquid (melting) or from liquid to gas (vaporization), without changing its temperature.

In contrast, specific heat refers to the amount of heat needed to raise the temperature of one gram of a substance by one degree Celsius, which is not the same as the heat required for a phase change. Conductive heat relates to the transfer of heat between materials in direct contact, rather than the heat involved in changing states of matter. Thermal energy is a broader term that encompasses all kinetic energy related to the temperature of a substance but does not specifically refer to the phase change process. Therefore, latent heat is the correct terminology for the energy associated with phase transitions.