Question

$\Delta H_f^0$ of water is $-285.8kJ{mol}^{-1}$. If enthalpy of neutralisation of monoacid strong base is $-57.3kJ{mol}^{-1},\Delta H_f^0$ of $O{H}^{-}$ ion will be:

• A. $-228.5kJ{mol}^{-1}$
• B. $+228.5kJ{mol}^{-1}$
• C. $+114.25kJ{mol}^{-1}$
• D. $-114.25kJ{mol}^{-1}$

Answer 1

The correct option is A $-228.5kJ{mol}^{-1}$

As given,

$\Delta H_f^0$ of water is $-285.8kJ{mol}^{-1}$ and

enthalpy of neutralization of monoacid strong base is $-57.3kJ{mol}^{-1}$

So,

$\Delta H_f^0$ of $O{H}^{-}$ = $-285+57.3=-228.5kJ/mol$