For the reaction

CHEMISTRY · Subjective · A Level · Chemistry · Thermodynamics · Thermodynamics

Problem

For the reaction

\mathrm{N_{2}(g) + 3\,H_{2}(g) \rightarrow 2\,NH_{3}(g)}

, the enthalpy change is

\Delta H = -92.2\,\text{kJ\,mol}^{-1}

and the entropy change is

\Delta S = -198\,\text{J\,mol}^{-1}\,\text{K}^{-1}

(per reaction as written). Calculate

\Delta G

at both

298\,\text{K}

and

800\,\text{K}

(assume

\Delta H

and

\Delta S

are temperature-independent), and identify at which of these two temperatures the formation of

\mathrm{NH_{3}}

is thermodynamically favored.