Question

The absolute enthalpy of neutralisation of the reaction:

MgO_(s) + 2HCl_(aq) → MgCl_2(aq) + H₂O_(l) will be

(a) -57.33 kJ mol^-1

(b) greater than -57.33 kJ mol^-1

(c) less than -57.33 kJ mol^-1

(d) 57.33 kJ mol^-1

Answer 1

The correct option is : (c) less than -57.33 kJ mol^-1

Explanation:

MgO is the oxide of weak base and we know that heat of neutralisation of 1 eq. of strong acid with strong base is - 57.33 kJ/mol. 

=> with weak base some heat is absorbed in dissociation of weak base. 

=> Heat of neutralisation of weak base with strong acid will be less than - 57.33 kJ/mol.