What is the amount of energy required to change a substance from the solid phase to the liquid phase called?

The amount of energy required to change a substance from the solid phase to the liquid phase is referred to as the heat of fusion. This term specifically describes the energy needed for a solid to overcome the forces holding its molecules together so that it can transition to a liquid state. The process involved is commonly observed when ice melts into water; the heat of fusion is the energy absorbed during this melting process.

The concept of heat of fusion indicates that this energy is specific to the substance undergoing the phase change, and it is measured in joules per gram or calories per gram, which defines how much energy is required for that specific material.

In contrast, the heat of vaporization refers to the energy needed for a liquid to become a gas, which is different from the melting process. Specific heat refers to the amount of energy needed to raise the temperature of a unit mass of a substance by one degree Celsius, while latent heat is a broader term that encompasses both the heat of fusion and the heat of vaporization, referring to the heat required for a phase change without a temperature change. Therefore, the correct choice specifically relates to the energy necessary for melting, which aligns with the definition of heat of fusion.