What is the opposite of evaporation?

2 Answers

t-nez's profile pic

t-nez | High School Teacher | (Level 3) Associate Educator

Posted on

The opposite of evaporation is condensation. Condensation describes the phase change from gas to liquid. 

Evaporation occurs when molecules at the surface of a liquid enter the gas phase at a temperature below the boiling point of the substance. Molecules in a liquid have a range of energies and some will have enough energy to overcome the surface tension of the liquid.

Liquid in an open container will evaporate until it reaches equilibrium with the atmosphere, which means that the rate of evaporation of liquid equals the rate of condensation of gas. Equilibrium is also called the saturation point. At 100% relative humidity the atmosphere is saturated with water vapor and the rate of evaporation will equal the rate of condensation.

Vaporization is the change from the liquid to the gas phase at a substance's boiling point. When the temperature of a gas is lowered to its boiling temperature it will begin to condense.  As with the change from liquid to gas, condensation occurs at temperatures other than the boiling point because of the range of energies of molecules in a substance. The particles with the lowest energies condense at the ambient temperature. The word condensation is used to describe this phase change both at the boiling/condensation temperature and at other temperatures. 

The rate of condensation of water vapor in the atmosphere is affected by temperature, pressure and humidity.

gsenviro's profile pic

gsenviro | College Teacher | (Level 1) Educator Emeritus

Posted on

Evaporation is the process in which a material changes from liquid to gas phase, upon addition of heat. An example is the evaporation of water to steam, when we heat it. Opposite of evaporation is condensation, a process in which a material changes from gas phase to liquid phase. Heat would be released in this process. An example of condensation is formation of water droplets on the outside of glass of cold water. Another example is the formation of dew or fog when we exhale on a cold day (especially visible if we breathe out on a piece of glass or on window panes). Another way to think of evaporation and condensation reactions is that evaporation is endothermic (since heat must be supplied) and condensation is exothermic (since heat is released). 

Hope this helps.