Unit of Standard Enthalpy of Fusion or Molar Enthalpy of Fusion

The standard enthalpy of fusion or molar enthalpy of fusion is a thermodynamic property that measures the amount of heat energy absorbed or released when a substance undergoes a phase change from solid to liquid at its melting point. It is represented by the symbol ΔHfus.

The unit of the standard enthalpy of fusion or molar enthalpy of fusion is KJ per Mol.

Explanation:

The standard enthalpy of fusion is defined as the enthalpy change per mole when a solid substance melts and becomes a liquid at its melting point under standard conditions of temperature and pressure. It is measured in kilojoules per mole (KJ/mol).

Why is the unit KJ per Mol?

The unit can be understood by considering the definition of enthalpy and the molar quantity of the substance undergoing fusion.

- Enthalpy is a measure of the heat energy of a system at constant pressure. It is given in joules (J) or kilojoules (KJ).
- The molar quantity refers to the number of moles of a substance. It is expressed in moles (mol).

When a substance undergoes fusion, a certain amount of heat energy is absorbed or released. This heat energy is measured per mole of the substance. Therefore, the unit of the standard enthalpy of fusion is KJ/mol.

Significance of the Unit:

The unit KJ/mol allows scientists to quantify the amount of energy required or released when a specific number of moles of a substance undergo fusion. It is a measure of the energy required to break the intermolecular forces and transform a solid substance into a liquid state.

By using this unit, scientists can compare the enthalpy of fusion of different substances and understand the energy requirements for phase changes. It is also used in thermodynamic calculations and can be used to determine the enthalpy change in other processes involving the conversion of a solid to a liquid.

In summary, the unit of the standard enthalpy of fusion or molar enthalpy of fusion is KJ/mol. This unit represents the amount of heat energy absorbed or released per mole of substance during the phase change from solid to liquid at the melting point.