The enthalpy of neutralisation of oxalic acid by a strong base is `- 25.4 kcal//mol`. The enthapy of neutralisation of a strong acid and strong base is `-13.7` kcal/equiv. The enthaply of dissociation of
`H_(2)C_(2)O_(4) hArr 2H^(+) + C_(2)O_(4)^(2-)` is

Options

A. `1.0 kcal//mol`
B. `2.0 kcal//mol`
C. `18.55 kcal//mol`
D. `11.7 kcal//mol`

Answer

B

Explanation

`H_(2)C_(2)O_(4) hArr 2H^(+) + C_(2)O_(4)^(2-) Delta H = x` (say)
`H^(+) + OH^(-) rarr H_(2)O [Delta H = - 13.7 kcal] xx 2`
`H_(2)C_(2)O_(4) + 2OH^(-) rarr C_(2)O_(4)^(2-) + 2H_(2)O, Delta H = - 25.4 kcal`
`x + (- 13.7 xx 2) = - 25.4 kcal`
`x - 27.4 = - 25.4`
`x = - 25.4 + 27.4 = 2.0 k cal mol^(-1)`