Evaporation

Definition

Evaporation is the process where molecules at the surface of a liquid gain sufficient energy to enter the gaseous phase. This typically occurs at temperatures below the boiling point of the liquid.

5 Must Know Facts For Your Next Test

1. Evaporation leads to cooling because it involves high-energy molecules leaving the liquid, reducing its average kinetic energy.
2. The rate of evaporation increases with higher temperature, greater surface area, and lower humidity.
3. Unlike boiling, evaporation occurs only at the surface of a liquid and can happen at any temperature.
4. In thermodynamics, evaporation is an endothermic process as it requires heat absorption from the surroundings.
5. Evaporation plays a crucial role in the water cycle by enabling water to transition from oceans and lakes into atmospheric vapor.

Review Questions

• Why does evaporation cause a cooling effect?
• How does temperature influence the rate of evaporation?
• What are three factors that affect the rate of evaporation?

Related terms

Boiling: A phase change where a liquid turns into vapor when its vapor pressure equals atmospheric pressure, occurring throughout the entire liquid.

Condensation: The process by which gas transitions into a liquid phase when it loses thermal energy.

Latent Heat: $$Q = mL$$ represents latent heat where $$Q$$ is heat absorbed or released during a phase change, $$m$$ is mass, and $$L$$ is latent heat constant.