Why does water take time to boil on the stove, but immediately stop once taken off the stove?
In: Physics
It takes a good bit of energy to heat water to it’s boiling point, under normal atmospheric conditions. (It takes less heat to boil at lower pressures) When you are heating up water, heat transfer from the stove to the water by conduction and convection. When water vaporizes into water vapor, it takes a good bit of the heat energy with it (out of the water and into the vapor). This is called latent heat of vaporization, which is a much faster process then conduction and convection. As a result, it requires constant heating to stay boiling. If the heat source is removed, that latent heat of vaporization quickly takes enough energy from the water to lower it’s temperature to just below boiling. At that point, heat is lost only though conduction and convection, so the temperature will only gradually decrease. If your pot is made of a thicker material that has a higher heat capacity, like an iron pot, there will be enough remaining heat in the pot itself to cause boiling for a short time after it’s removed from the stove. Aluminum pots are thin and don’t retain heat for long, so you basically see boiling stop almost immediately after removing from the stove.
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