DISSOCIATION NEUTRALISATION

Question 1

The standard enthalpy change of neutralisation of the weak acid HCN
by sodium hydroxide is –11.7kJmol–1 while that of the strong acid HCl
is –57.9kJmol–1.
Explain the difference between these values.

Answer 1

Because HCN is a weak acid, it only partially ionises in solution.
To produce enough H⁺ ions for neutralisation, more HCN molecules must ionise.