A reaction has ΔH = +50 kJ/mol and ΔS = +200 J/(mol·K). It becomes spontaneous above what temperature?

250 K (ΔG = 0 when T = ΔH/ΔS) ΔG = ΔH − TΔS. Spontaneous when ΔG < 0. T ΔH/ΔS = 50000/200 = 250 K.

250 K (ΔG = 0 when T = ΔH/ΔS)

Gibbs Free Energy and Thermodynamic Favorability

AP Chemistry· difficulty 4/5

A reaction has ΔH = +50 kJ/mol and ΔS = +200 J/(mol\cdotK). It becomes spontaneous above what temperature?

Explanation

ΔG = ΔH - TΔS. Spontaneous when ΔG < 0. T > ΔH/ΔS = 50000/200 = 250 K.

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