Question

Enthalpy change for the reaction, $4H_{\left(g\right)}\to 2H_{2\left(g\right)}$ is $-869.6kJ$. The dissociation energy of $H-H$ bond is:

• A. $-434.8kJ$
• B. $-869.6kJ$
• C. $+434.8kJ$
• D. $+217.4kJ$

Answer 1

Answer: (C)

$+434.8kJ$

$4H_{\left(g\right)}\to 2H_2\left(g\right),\Delta H=-869.6KJ.$
$2H_2\to 4H\left(g\right),\Delta H=+869.6KJ.$
$H_2\to 2H\left(g\right),\Delta H=\frac{+869.6}{2}=+434.8KJ.$