Question

In which of the following reaction enthalpy of neutralization is least negative?

• A. HF and NaOH
• B. $H_{3}P{O}_4$ and $KOH$
• C. $H_{2}S{O}_4$ and $N{H}_{4}OH$
• D. $HCN$ and $N{H}_{4}OH$

Answer 1

The correct option is A HF and NaOH

Ionisation of $HF$ produces $F^{-}$ & $H^{+}$ .

The size of $F^{-}$ is small. So, it is highly hydrated which releases high amount of energy, which results for higher neutralization enthalpy than strong acids.