Why does evaporation cool the liquid left behind?

• A. Because the liquid absorbs heat from the air during evaporation.
• B. Because the molecules with the highest kinetic energy escape, lowering the average energy of the remaining liquid.
• C. Because the molecules with the lowest kinetic energy escape, leaving behind higher energy molecules.
• D. Because evaporation increases the temperature of the liquid by adding energy to it.

Answer: (B)

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 more likely to escape because they can overcome the attractive forces holding them in the liquid.
4. As these high-energy molecules leave, the average kinetic energy of the remaining molecules in the liquid decreases.
5. Since temperature is directly related to the average kinetic energy of molecules, the decrease in average kinetic energy results in a cooling effect on the liquid left behind.