What is the term for heat that causes a change in state without changing temperature?

Latent heat is the correct term for the heat that causes a change in state without changing the temperature of a substance. This energy is required when a substance transitions between solid, liquid, or gas phases, such as ice melting to water or water evaporating to steam.

During these phase changes, the temperature of the substance remains constant as the energy goes into breaking the molecular bonds or altering the physical structure of the substance rather than increasing its temperature. For example, when ice melts, it absorbs heat from the environment without a rise in temperature until it has completely transformed into water.

In contrast, specific heat refers to the amount of heat required to change the temperature of a unit mass of a substance by one degree Celsius, and thermal energy generally encompasses the total kinetic energy of particles in a substance. Active heat is not a standard term used in thermodynamics or physics associated with state changes. Thus, latent heat specifically addresses the energy involved in phase changes at constant temperature.