Final answer:
The question seeks to determine at which temperature the reaction 2NO(g) + O₂(g) ⇌ 2NO₂(g) is spontaneous. Spontaneity can be assessed via the Gibbs free energy, which takes into account the relationship between enthalpy, entropy, and temperature. The specific temperature requires calculating when ΔG becomes negative.
Step-by-step explanation:
The question is asking under what temperature conditions is the reaction 2NO(g) + O₂(g) ⇌ 2NO₂(g) spontaneous. The spontaneity of a reaction depends on the Gibbs free energy change (ΔG), which is related to the enthalpy (ΔH) and entropy (ΔS) changes and the temperature (T). From the provided information, we know that the enthalpy change of the reaction is -92.9 kJ/mol of O₂ when forming NO₂ and that the reaction is endothermic with a positive ΔH when NO combines with O₂. Spontaneity is influenced by both temperature and entropy. If ΔH is negative and ΔS is negative, a reaction is spontaneous at low temperatures, which must be considered along with the provided enthalpy value to determine the temperature at which the reaction becomes nonspontaneous. Therefore, the temperature at which the reaction 2NO(g) + O₂(g) ⇌ 2NO₂(g) is spontaneous (and goes in the forward direction) can be estimated by applying the Gibbs free energy equation ΔG = ΔH - TΔS and setting ΔG to less than zero.