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# Heat of Fusion Formula – Equation and Problem Solved with Example

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The heat of fusion of a substance the total change in enthalpy by enforcing g heat or energy in limited quantity and converting from one state to another by making the pressure constant. In simple terms, it can be defined as the total amount of heat that will be introduced to convert the crystalline fraction into disordered state. Based on the degree of crystallinity, this is easy measuring heat of fusion in Chemistry. Let is see the heat of fusion formula ahead –

### Heat of fusion Formula

$\ ΔHf =\frac{q}{m}$
where
q is heat energy
m is mass
ΔHf is heat of fusion

Solids should be heated to a point when the molecules holding their bonds start breaking apart and results in liquid ahead. The most common example is conversion of ice into liquid water. The process is better known as the melting and makes the substances little less organized than usual.

When some substance is converted to liquid state from the solid ones then change in enthalpy is positive usually. At the same time, if substance is transformed from a liquid state to the solid state then the change is enthalpy is negative and the process is popular with the name freezing.

In the case of freezing, the substances usually become more ordered than usual. This is easy to calculate the heat of fusion when temperature or pressure is generally constant during the entire phase. The process can also be visualized clearly when seen in the cooling chart.