The heat of fusion of any substance is the important calculation of the heat. It is the change in the value of the enthalpy by providing energy i.e. heat, for a specific quantity of the substance. It will change its state from a solid to a liquid keeping the pressure constant. The heat of fusion of any sample will measure the amount of heat that needs to be introduced to convert its crystalline fraction into the disordered state. The topic explains the heat of fusion formula with examples. Let us learn it!

Concept of the Heat of Fusion

‘Heat of fusion’ measures the amount of energy required to melt a given amount of a solid at its melting point temperature. In other words, it also represents the amount of energy given up when a given mass of liquid solidifies. For example, water has a heat of fusion of 80 calories per gram. It means that it takes 80 calories of energy to melt 1 gram of ice at the temperature of zero degrees C into the water at zero degrees C. Heat of fusion values will differ for the different materials.

For example, we may see that heat gained by ice is equal to the heat lost by the water. We denote the Heat of fusion by the symbol ΔHf.

Heat of Fusion Formula

When a solid material turns into the liquid, then it is what we know as melting. This melting process will need an increase in energy to allow the solid-state particles to break free from each other. This energy input is the heat of fusion. The heat of fusion is not the same for all substances, but it is a constant value for each individual kind of substance.

The Formula for the Heat of Fusion:

We compute it as: ΔHf=qm

ΔHf heat of fusion

q Heat

m mass