• # question_answer 32) For the reaction; $2A(g)+B(g)\to 2D(g)$ $\Delta {{U}^{{}^\circ }}_{298\,K}=-10.5kJ$ and $\Delta {{S}^{{}^\circ }}=-44.1J{{K}^{-1}}$ Calculate $\Delta {{G}^{{}^\circ }}_{298K}$ for the reaction and predict whether the reaction is spontaneous or not.

Answer:

$\Delta {{H}^{{}^\circ }}=\Delta {{U}^{{}^\circ }}+\Delta {{n}_{g}}RT$ $=-10.5+(-1)\times 8.314\times {{10}^{-3}}\times 298$ $=-12.978kJ$ According to Gibbs-Helmholtz equation: $\Delta {{G}^{{}^\circ }}=\Delta {{H}^{{}^\circ }}-T\Delta {{S}^{{}^\circ }}$ $=-12.978-298(-44.1\times {{10}^{-3}})$ $=+0.164kJ$ Since, $\Delta G{}^\circ \text{ }=+ve$, hence the reaction is non-spontaneous.

You need to login to perform this action.
You will be redirected in 3 sec