NATE Gas Heating Practice Exam

What is latent heat?

1. Heat that causes a change in temperature with no change in state

2. Heat that causes a change in state with no change in temperature

3. The large amount of heat involved when a gas condenses into a liquid

4. Both b and c are correct

The correct answer is: Both b and c are correct

Latent heat refers to the heat energy that is absorbed or released by a substance during a phase change without a change in temperature. This phenomenon occurs when a substance transitions from one state of matter to another, such as from solid to liquid (melting), liquid to gas (vaporization), or gas to liquid (condensation). In particular, the process of condensation, where a gas turns into a liquid, involves a significant amount of heat being released. During this process, even though heat is being transferred, the temperature of the substance remains constant until the phase change is complete. Similarly, when a substance boils or evaporates, it absorbs heat without an increase in temperature until all of the substance has changed into a gas. Therefore, both aspects of heat transfer during phase changes, as described in the options, correctly represent latent heat. This is why the answer includes both the change in state with no change in temperature and the specific situation of gas condensing into a liquid as correct interpretations of latent heat.