> Can someone explain the boiling water on his tongue? The main thing stopping the molecules of a liquid boiling away (flying off, out of the container) is the

> Can someone explain the boiling water on his tongue? The main thing stopping the molecules of a liquid boiling away (flying off, out of the container) is the pressure exerted by the gas above or around them. If you make the liquid molecules move faster (i.e. give them energy, i.e. heat them up), a greater proportion of them will be able to overcome this pressure. So heating increases evaporation and leads to boiling - which we're familiar with. Alternatively, if you reduce the pressure of the gas pushing the liquid molecules together, you don't need to heat up the liquid as much to get the same evaporation/boiling effect. Reduce the gas pressure enough and the liquid will boil at a very low temperature.