Why is latent heat a type of heat if there is no temperature difference involved during phase change?
Heat is commonly defined as an energy in transit due to temperature difference. For sensible heat, this is quite evident. But latent heat, or the “heat” involved during phase change, is not associated with temperature change. So, is latent heat not really a type of heat or is there something that I’m missing?
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“Latent heat” is a bit of a confusing term, because it is only heat on one side of the equation. It’s actually energy that can turn into heat, or heat that turns into a different type of energy.
It’s similar to how gasoline can be at (say) room temp, but when you burn it, it becomes very hot. The heat that is released used to be stored in the chemical bonds inside the gasoline – it is turned from chemical into heat energy.
When you melt an ice cube, you have to put a lot of energy in to make it change from solid to liquid. This energy goes into loosening the bonds between the water molecules, rather than into heating them up. So heat energy gets converted into chemical energy. If you freeze the water again, that energy will get turned back into heat (but now this is heat that you need to extract, in order to get it to freeze).
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