Question

For the reaction. 2 A (g) + B (g) → 2 D (g), ΔU° = 10.5 kJ and ΔS° = – 44.10 $JK^{-1}$. Calculate ΔG° for the reaction and predict whether the reaction may occur spontaneously.

Answer 1

" ${ \Delta H }^{ \circ}\quad =\quad \left( { \Delta U }^{ \circ}\quad +\quad { \Delta n }_{ \circ}RT \right)$

$=\quad -10.5\quad J\quad +\quad (-1)\quad \times \quad 298\quad \times \quad 8.314$

${ \Delta H }^{ \circ}\quad =\quad -2.488\quad KJ$

${ \Delta G }^{ \circ}\quad =\quad { \Delta H }^{ \circ}\quad -\quad { T\Delta S }^{ \circ}$

$=\quad -2.488\quad +\quad 13141.8\\ { \Delta G }^{ \circ}\quad =\quad 1313\quad J.mol^{ \quad -1 }$

Since ${ \Delta G }^{ \circ}$is positive, the reaction is non-spontaneous."