The reaction C(s)+ CO₂(g)→ 2CO(g)is spontaneous only at temperatures in excess of 1100 K.We can conclude that A)ΔG° is negative for all temperatures. B)ΔH° is negative and ΔS° is negative. C)ΔH° is positive and ΔS° is positive. D)ΔH° is negative and ΔS° is positive. E)ΔH° is positive and ΔS° is negative.

Question

Quizplus · Accepted Answer

For a reaction to be spontaneous only at high temperatures, the entropy change (ΔS°) must be positive (favoring the reaction at high temperatures), and the enthalpy change (ΔH°) must be positive (requiring heat input, which becomes favorable at higher temperatures). This is because the Gibbs free energy change (ΔG°) is given by ΔG° = ΔH° - TΔS°. If ΔH° is positive and ΔS° is positive, at low temperatures the positive ΔH° term dominates making ΔG° positive (non-spontaneous), but at high temperatures, the TΔS° term can overcome the ΔH° term, making ΔG° negative (spontaneous).

The Reaction C(s)+ CO2(g)→ 2CO(g)is Spontaneous Only at Temperatures in Excess

The Reaction C(s)+ CO₂(g)→ 2CO(g)is Spontaneous Only at Temperatures in Excess