What does heat capacity refer to?

Heat capacity is defined as the amount of energy required to raise the temperature of a substance by 1° C (or 1 K). This concept is fundamental in thermodynamics, as it quantifies how much heat a substance can hold and how its temperature will change in response to the addition of heat.

When a given amount of heat energy is added to a substance, the temperature increase will depend on the substance's heat capacity. Materials with high heat capacities can absorb more heat without a significant change in temperature, while those with lower heat capacities will experience a more pronounced temperature change with the same amount of heat added.

The other options address related but distinct concepts. The first choice refers to the specific process of vaporization, which is not a general measure of heat capacity. The third option deals with energy in chemical bonds, which is related to chemical energy and potential energy rather than the thermal properties of a substance. The fourth choice describes kinetic energy, which relates to the motion of molecules but does not directly define heat capacity itself. Thus, the correct understanding of heat capacity rests on its definition as the energy required to raise the temperature of a substance by a specific amount.