QJEEM23Ch18bd: JEE Main 2023 Chemistry - Class 11 JEEM23Ch18bd Solution: of heat is required to melt one mole of sodium chloride and the …

The heat required to melt one mole of a substance is known as its molar enthalpy of fusion, denoted as $\Delta H_\mathrm{fus}$ . For sodium chloride, $\Delta H_\mathrm{fus}$ is $30.4\ \mathrm{kJ/mol}$ .

The entropy change at the melting point is given by $\Delta S = \frac{\Delta H_\mathrm{fus}}{T_\mathrm{m}}$ , where $T_\mathrm{m}$ is the melting point in Kelvin. Substituting the given values, we get:

$28.4\ \mathrm{J/K/mol} = \frac{30.4\ \mathrm{kJ/mol}}{T_\mathrm{m}}$

Solving for $T_\mathrm{m}$ , we get:

$T_\mathrm{m} = \frac{30.4\ \mathrm{kJ/mol}}{28.4\ \mathrm{J/K/mol}} = 1070.4\ \mathrm{K}$

Rounding off to the nearest integer, the melting point of sodium chloride is $\boxed{1070\ \mathrm{K}}$ .