For the reaction of oxygen and nitrogen to form nitric oxide, consider the following thermodynamic dа ta: ΔH∘rxn 180.5 kJ/mol ΔS∘rxn 24.8 J / (mol⋅K) Calculate the temperature above which this reaction is spontaneous. Express your answer numerically in kelvins.

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Chemistry

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19 August, 21:59

For the reaction of oxygen and nitrogen to form nitric oxide, consider the following thermodynamic dа ta: ΔH∘rxn 180.5 kJ/mol ΔS∘rxn 24.8 J / (mol⋅K) Calculate the temperature above which this reaction is spontaneous. Express your answer numerically in kelvins.

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Answers (1)

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Averie · Answer 1

7.28 * 10³ K

Explanation:

Let's consider the following reaction.

N₂ (g) + O₂ (g) → 2 NO (g)

The reaction is spontaneous when the standard Gibbs free energy (ΔG°) is negative. ΔG° is related to the standard enthalpy of the reaction (ΔH°) and the standard entropy of the reaction (ΔS°) through the following expression.

ΔG° = ΔH° - T. ΔS°

If ΔG° < 0,

ΔH° - T. ΔS° < 0

ΔH° < T. ΔS°

T > ΔH°/ΔS° = (180.5 * 10³ J/mol) / (24.8 J/mol. K) = 7.28 * 10³ K

The reaction is spontaneous above 7.28 * 10³ K.