What does specific heat capacity measure?

Specific heat capacity is a fundamental concept in thermodynamics that quantifies how much heat energy is required to change the temperature of a substance. The correct choice reflects that specific heat capacity measures the amount of heat needed to raise the temperature of one kilogram of a substance by one degree Celsius.

This definition is crucial because it emphasizes the relationship between heat energy, mass, and temperature change. Each material has a unique specific heat capacity, which means that different substances respond differently to the same amount of heat energy. This property is particularly important in applications such as cooking, climate science, and material engineering, where understanding how substances will react to heat input is essential.

In contrast, the other options describe concepts that do not accurately define specific heat capacity. For instance, some focus on temperature change itself, which is a result of applying heat rather than the heat needed for that change. Others mention phase changes or total energy, which relate to different aspects of thermodynamics but do not pertain to the measurement of heat capacity as defined.