Question

The enthalpy of neutralisation of NH₄OH with HCl is −51.46 kJ/mol⁻¹ and the enthalpy of neutralisation of NaOH with HCl is −55.90 kJ/mol⁻¹. The enthalpy of ionisation of NH₄OH is ______.

पर्याय

• − 107.36 kJ/mol⁻¹

• − 4.44 kJ/mol⁻¹

• + 107.36 kJ/mol⁻¹

• + 4.44 kJ/mol⁻¹

Answer 1

The enthalpy of neutralisation of NH₄OH with HCl is −51.46 kJ/mol⁻¹ and the enthalpy of neutralisation of NaOH with HCl is −55.90 kJ/mol⁻¹. The enthalpy of ionisation of NH₄OH is + 4.44 kJ/mol⁻¹.

Explanation:

\[\ce{NH4OH(l) + HCl(l) -> NH4Cl(s) + H2O(l)}\]

ΔH₁ = −51.46 kJ/mol⁻¹ ....(i)

\[\ce{NaOH(l) + HCl(l) -> NaCl(s) + H2O(l)}\]

ΔH₂ = −55.90 kJ/mol⁻¹ .....(ii)

On subtracting equation (ii) from equation (i)

\[\ce{NH4OH(l) -> NH^+_4(aq) + OH^-(aq)}\]

Enthalpy of ionisation = −51.46 − (−55.90) = 4.44 kJ/mol⁻¹