The heat solution is defined as the difference in the enthalpy related to the dissolving substance in a solvent at constant pressure which is leading in infinite dilution. The unit of solution enthalpy is KJ/mol.
The enthalpy change is observed when the solute is dissolved in the solvent. When solid or gas is dissolved in the solvent the heat is absorbed. This process is known as heat dissolution or heat solution. The heat solution is measured in terms of a calorimeter.
The formula of the heat of solution is expressed as,
ΔHwater = mass water × ΔTwater × specific heat water
ΔH = heat change
mass water = sample mass
ΔT = temperature difference
Specific heat = 0.004184 kJ/g∘C.
The heat absorbed when hydrated salt (Na2CO3.10H2O) is dissolved at 291K isothermally in a large quantity of water is 65 KJ per mole solute. Determine the heat of crystallization of 1kg Na2CO3.10H2O.
m = 65 kJ per mol
ΔT = 291K
Specific heat = 0.004184 KJ/g∘C
Substitute in the given formula, we get
ΔHwater= masswater × ΔTwater × specific heatwater
= 65 × 291 × 0.004184
Therefore, ΔHwater = 79.140 kJ/Kg solute