|
You don't have to boil a liquid to make it hot enough for particles to escape. Liquids like water, at room temperature, contain billions of particles moving at many different speeds. Their average speed is reflected in the liquid's cooler temperature. But there are some particles that are moving very slow, and some that are moving very fast. These fast ones are always escaping from the liquid. This is called evaporation. The hotter you make the temperature of the liquid, the higher the average speed of its particles, and the more fast ones there are to escape. For water at Incidentally, when these faster particles leave, this lowers the average temperature of the ones left behind. So when liquids evaporate at room temperature, they get cooler. This is how you stay cool by sweating ... evaporating liquid from your skin 'takes the heat from your body' to use in setting its particles free, leaving you cooler. |