What happens when water boils?

It goes from liquid to gas (becomes steam). What you are witnessing when you see water freeze or turn to steam are phase changes! However, it takes a lot more than 1 calorie to make water go from a liquid at 100C to steam at 100C! It also takes a lot more than 1 calorie to make water go from a solid at 0C to liquid at 0C! Hey!! There's not even a temperature change here! Why is that?! The obvious reason is because these phase changes require more than 1 calorie of heat energy. How many calories you ask? Good question! It requires an input of 80 calories (144 Btu/lb) per gram of pure water to cause it to go from a solid at 0C to a liquid at the same temperature (Latent Heat of Fusion), and it requires 539 calories (970 Btu/lb) per gram of pure water to cause it to go from a liquid at 100C to a gas at the same temperature (Latent Heat of Vaporization)! Let's look at a graph depicting the energy relationships as water changes state from solid to liquid to gas... It is important to ...  more