Acetic acid `(` ethanoic acid `)` and hydrochloric acid react with `KOH` solution. The enthalpy of neutralisation of ethanoic acis is `-55.8kJ mol^(-1)` while that of hydrochloric acid is `-57.3kJ mol^(-1)` . Can you think of how are these different?`

Explanation

Hydrochloric acid and `KOH`, both are strong.
They are completely ionised in aqueous solutions of their own and no energy is needed for their ionisation. The cation of the base and the anions of the acid cancel out from both sides if the equation. The neutralisation simply involves the combination between `H^(o+)` ions or the acid and `OH^(Θ)` ions of the base in aqueous solution.
`K^(o+)(aq)+overset(Θ)(OH)(aq)+H^(o+)(aq)+Cl^(Θ)(aq) rarr K^(o+)(aq)+Cl^(Θ)(aq)+H_(2)O(l)`
By cancelling the common ions, we get
`overset(Θ)(OH)(aq)+H^(o+)(aq)rarrH_(2)O(l)`
Acetic acid is weak which is not completely ionised in aqueous solution. But as `KOH` is a strong, it gas to be ionised fully in order to complete the neutralisation reaction. some energy is needed for the purpose.
Therefore, the enthalpy of neutralisation of ethanoic acid is `-55.8 kJ mol^(-1)` while that of `HCl` is `-57.3 kJ mol^(-1)`.