Question

For a dimerization reaction,
$2 A ( g ) \rightarrow A _{2}( g )$
at $298 K , \Delta U ^{\ominus},=-20 kJ mol ^{-1}, \Delta S ^{\ominus}=-30 J$
$K ^{-1} mol ^{-1}$, then the $\Delta G ^{\ominus}$ will be______J.

Answer 1

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

$=\left(\Delta U ^{\circ}+\Delta n _{ g } RT \right)- T \Delta S ^{\circ}$

$\left.=\left[\{-20+(-1)) \frac{8.314}{1000} \times 298\right\}-\frac{298}{1000} \times(-30)\right] kJ$

$=-13.537572 kJ$

$=-13537.57$ Joule