Why is evaporation considered a cooling process?

• A. Because all molecules in the liquid lose energy simultaneously during evaporation.
• B. Because evaporation adds heat to the liquid, increasing its temperature.
• C. Because evaporation only occurs at high temperatures, causing the liquid to cool.
• D. Because the molecules with the highest kinetic energy escape from the liquid, lowering the average energy of the remaining molecules.

Answer: (D)

Verified step by step guidance

1. Understand that evaporation is the process where molecules at the surface of a liquid gain enough energy to overcome intermolecular forces and escape into the gas phase.
2. Recognize that molecules in a liquid have a range of kinetic energies, with some moving faster (higher energy) and some slower (lower energy).
3. During evaporation, the molecules with the highest kinetic energy are the ones most likely to escape from the liquid into the vapor phase.
4. As these high-energy molecules leave, the average kinetic energy of the remaining molecules in the liquid decreases.
5. Since temperature is a measure of the average kinetic energy of molecules, the decrease in average kinetic energy results in a lowering of the liquid's temperature, making evaporation a cooling process.