A Level Chemistry OCR Practice Exam

Which statement best describes 'specific heat capacity'?

1. The capacity to store heat

2. The heat needed for temperature changes of a substance

3. The energy change during phase transitions

4. The heat capacity per unit mass of a substance

The correct answer is: The heat capacity per unit mass of a substance

Specific heat capacity is defined as the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius (or one Kelvin). The concept emphasizes the relationship between heat energy and temperature change in relation to the mass of the substance. This definition indicates that the specific heat capacity is a measure of how much energy a substance can absorb per unit mass before experiencing a temperature change. Therefore, it is essential for understanding thermal properties and energy transfer in materials. In contrast, the other options describe different aspects of thermodynamics or general heat transfer but do not accurately capture the definition of specific heat capacity. The first option focuses on the general ability to store heat, which lacks specificity regarding mass and temperature change. The second option refers to the heat needed for temperature changes, which is broader and does not specify the relationship to per unit mass. The third option pertains to energy changes during phase transitions, which is a separate concept involving latent heat rather than the specific heat capacity.