Question

Define the following terms:
Enthalpy of fusion

Answer 1

Hint: Enthalpy of fusion is also called the latent heat of fusion. Enthalpy of fusion is related to the difference in energy of the solid and liquid state of a particular material at constant temperature and pressure.

Complete step by step solution:
Enthalpy of fusion is the energy required for a specific quantity of the substance to change its state from solid to liquid at constant pressure. Here, we generally provide energy by heat.
-Enthalpy of fusion is also known as latent heat of fusion.
e.g. In melting of ice weighing 1 kg, the amount of energy required is 333kJ with no temperature change. So, this is the Enthalpy of fusion of ice.
-Here during the process of conversion of solid-state to the liquid state, the temperature remains constant.
-When the mass of the substance is taken as 1 kg, then the enthalpy is called specific enthalpy of fusion or specific heat of fusion.
-We know that liquids have higher thermal energy than the solids. So, we can say that we need to supply external energy in order to convert solid into a liquid. While the energy needs to be released in order to freeze the liquid.
-Heat of solidification is exactly opposite to the heat of fusion or enthalpy of fusion. It is the energy released when a substance changes its physical state from liquid to solid.

Note: We use the word latent in the latent heat of fusion because the heat we give to the material does not affect the temperature of the material. Actually only the physical state of the material changes here.