Gas Fitter Practice Test

Which type of heat is removed or added to cause a change in state without affecting temperature?

1. Sensible heat

2. Radiant heat

3. Latent heat

4. Super heat

The correct answer is: Latent heat

The correct response is latent heat, which refers to the heat energy that is either absorbed or released during a phase change of a substance, such as melting, freezing, vaporization, or condensation, without causing a change in temperature. This concept is crucial in understanding phase transitions, as it highlights that the energy is used to break or form intermolecular bonds rather than to increase kinetic energy (which is what would cause a temperature change). For instance, when ice melts to water, it absorbs heat (latent heat of fusion) but remains at 0°C until all the ice has turned into water. Similarly, when water boils and turns into steam, it requires a significant amount of heat (latent heat of vaporization) but stays at 100°C until all the liquid has been converted. Sensible heat leads to temperature changes; it is the energy that causes a rise or fall in temperature without a change in state. Radiant heat refers to energy transfer in the form of electromagnetic waves, which can cause temperature changes in materials they strike. Superheat relates to the phase of a substance being in a gas state beyond its boiling point, also influencing temperature. Thus, latent heat is uniquely related to phase changes without temperature alteration.