 Now normally when you add heat to an object its temperature goes up as you add the heat save put a flame under it the atoms will jiggle faster or they will The chemical bonds will be more stretched the atoms will spin around more But there is one particular special situation where you can add heat Say put a fire under something and it will not change the temperature Energy is still going into whatever it is you're heating up, but the energy is actually doing something different. It's breaking chemical bonds This is a concept of latent heat Our latent heat is the energy needed to change one kilogram of a substance from one state of matter to another Now what do I mean by state of matter? Well state of matter is like solid liquid or gas or in fact plasma or bones like Bose-Einstein condensate So for example, this is the energy needed to turn one kilogram of ice at Zero degrees centigrade Into one kilogram of water at zero degrees Integrate and it turns out that even though the atoms are going at the same speed in the water as they were in the ice beforehand A lot of energy is needed because it's breaking all the chemical bonds that hold the crystals close together Likewise, if you take one kilogram of water at a hundred degrees and you boil it dry So it turns into one kilogram of steam at a hundred degrees the Potassium changed the atoms are going at the same speed at the end as they were in the beginning However, you've had to break all the bonds that are holding them together in liquid making them all free as it is in a gas So that is called the latent heat