Question

Enthalpy of Hydration of ${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$ is

Answer 1

Enthalpy of hydration:-

• Enthalpy of hydration is defined as the quantity of energy generated when one mole of gaseous ions is diluted.
• It may be thought of as an enthalpy of solvation, using water as the solvent.
• Hydration enthalpy, commonly known as hydration energy, is always negative.
• Because there are no bonds to be broken, there is no endothermic process in hydration; only energy is released when the bonds between the ions and the water form.
• But for hydrated salts the enthalpy of hydration is positive.
• When the hydrated salt dissolves, the exothermic reaction of formation of hydrated ions is no more effective, so you have only the dissolution process, which in most cases is endothermic (roughly, positive enthalpy variation).
• According to data, the enthalpy of Hydration of hydrated Copper Sulphate ${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$ is $11.7\mathrm{kJ}{\mathrm{mol}}^{-1}$ i.e., positive.

So, the enthalpy of Hydration of ${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$ is positive.