Answer
To classify the processes as either endothermic or exothermic, we need to understand the energy changes involved in each phase transition.
- Evaporation: Endothermic – This process requires energy to convert liquid into vapor, absorbing heat from the surroundings.
- Melting: Endothermic – Melting ice into water involves heat absorption, allowing the solid to transition into a liquid state.
- Condensation: Exothermic – During condensation, vapor transitions to liquid, releasing heat into the environment, thus giving off energy.
- Sublimation: Endothermic – Sublimation, such as dry ice turning into gas, needs an input of energy to break the bonds between solid particles.
- Freezing: Exothermic – When a liquid turns into a solid, it releases heat to its surroundings as energy is lost.