What distinguishes an endothermic phase change from an exothermic phase change?

What distinguishes an endothermic phase change from an exothermic phase change?

• A. Endothermic changes release heat, while exothermic changes absorb heat
• B. Endothermic changes absorb heat, while exothermic changes release heat
• C. Both types absorb heat
• D. Both types release heat

Answer: (B)

In this context, an endothermic phase change is characterized by the absorption of heat energy from the surroundings, resulting in a temperature decrease in the surrounding environment. Classic examples include processes like melting, where a solid absorbs heat to transition to a liquid state, and vaporization, where a liquid absorbs heat to become a gas. Conversely, exothermic phase changes involve the release of heat energy to the surroundings, typically causing the temperature of the surroundings to increase. Examples include freezing, where a liquid releases heat as it transforms into a solid, and condensation, where a gas releases heat as it changes to a liquid. Understanding this distinction is critical because it describes the fundamental energy exchanges occurring during phase transitions, which play a vital role in thermodynamics and energy conservation in various chemical and physical processes.

In this context, an endothermic phase change is characterized by the absorption of heat energy from the surroundings, resulting in a temperature decrease in the surrounding environment. Classic examples include processes like melting, where a solid absorbs heat to transition to a liquid state, and vaporization, where a liquid absorbs heat to become a gas.

Conversely, exothermic phase changes involve the release of heat energy to the surroundings, typically causing the temperature of the surroundings to increase. Examples include freezing, where a liquid releases heat as it transforms into a solid, and condensation, where a gas releases heat as it changes to a liquid.

Understanding this distinction is critical because it describes the fundamental energy exchanges occurring during phase transitions, which play a vital role in thermodynamics and energy conservation in various chemical and physical processes.