Which phase change involves a substance absorbing heat without a change in temperature?

The phase change that involves a substance absorbing heat without a change in temperature is associated with the concept of latent heat. During a phase transition, such as melting or boiling, the energy supplied is used to overcome the forces holding the molecules together in their current phase rather than increasing the temperature of the substance.

In the case of melting, for example, a solid absorbs heat to convert into a liquid; however, the temperature of the solid remains constant while this transition is occurring until all of the solid has melted. Similarly, boiling involves a liquid transitioning into a gas, where the temperature remains constant during the boiling process until the entire liquid has converted to vapor.

Latent heat quantifies this energy exchange during phase changes, indicating that heat is absorbed or released while the temperature of the substance stays stable.