You look out on the street or road and you see water. An hour later in bright sunshine, it is gone! Or wet clothes are hung out on a line, and by the end of the day, they are dry. Where did the water go?

We say the water evaporates. But what does this mean? Evaporation is the process by which a liquid that is exposed to air gradually becomes a gas or vapor. Many liquids evaporate quite quickly, much more quickly than water. This is true of alcohol, gasoline, and ammonia. Some liquids, such as mercury, evaporate very slowly.