Do Liquids Cool As They Evaporate?
Boiling Point and Evaporation The temperature of a liquid is a measurement of the average speed of the molecules. The molecules in a liquid are attracted to each other, but at a certain temperature they move so fast that they pull away from each other. That temperature is called the boiling point, at which the liquid turns into a gas as its molecules spread into the air. Individual molecules, however, can leave a liquid at any point, in a process called evaporation. Temperature of Individual Molecules and Evaporation The rate or temperature of individual molecules in a quantity of liquid varies greatly. Some move very quickly while others are very slow. A puddle of water has millions of molecules, and at any point a few move quickly enough to escape the pull of the other molecules and disperse into the air. When they do, these molecules are said to evaporate. Cooling Effect When the fastest few molecules jump off the surface of the liquid, this lowers the average temperature. If a good
