The absolute enthalpy of neutralization of the reaction,
`MgO(s)+2HCl(aq.)+H_(2)O(l)` will be

Options

A. less than `-57.33 kJ mol^(-1)`
B. `-57.33 kJ mol^(-1)`
C. greater than `-57.33 kJ mol^(-1)`
D. `57.33 kJ mol^(-1)`

Answer

C

Explanation

The absolute value of enthalpy of neutralisation of this reaction is greater than `-57.33 kJ mol^(-1)` . This is due to very high enthalpy of hydration of `Mg^(2+)` ion. Infact the `DeltaH` for this reaction is nearly `-146 kJ`. Thus enthalpy of neutralisation per mole of `H^(+) ion` is nearly`-73 kJ`, which is greater than enthalpy of neutralisation of strong acid `V_(s)` strong base i.e., `-57.33 kJ`.