The absolute enthalpy of neutralisation of the reaction: : $\mathrm{MgO}_{(s)}+2 \mathrm{HCl}_{(a q)}$…
The absolute enthalpy of neutralisation of the reaction: : $\mathrm{MgO}_{(s)}+2 \mathrm{HCl}_{(a q)}$ $\rightarrow \mathrm{MgCl}_{2(a q)}+\mathrm{H}_2 \mathrm{O}_{(\cap}$ will be:
$-57.33 \mathrm{~kJ} \mathrm{~mol}^{-1}$
greater than $-57.33 \mathrm{~kJ} \mathrm{~mol}^{-1}$
less than $-57.33 \mathrm{~kJ} \mathrm{~mol}^{-1}$
$57.33 \mathrm{~kJ} \mathrm{~mol}^{-1}$
Solution
$\mathrm{MgO}$ is salt of weak base. Thus, enthalpy of neutralisation for $\mathrm{MgO}$ will be less than $-57.33 \mathrm{~kJ} \mathrm{~mol}^{-1}$.
Related Theory
The enthalpy of neutralization of any strong acid with a strong base is always the same, i.e., $57.1 \mathrm{~kJ}$. This is because the strong acids, strong bases and the salts they form, are all completely ionized in dilute aqueous solution.