A chemist considers coupling each of the following unfavorable steps to a highly…
CHEMISTRY · Subjective · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
A chemist considers coupling each of the following unfavorable steps to a highly exergonic step with ΔG° = –50 kJ (temperature-independent). For the unfavorable steps:
• Set A: ΔH° = +60 kJ, ΔS° = +150 J mol⁻¹ K⁻¹
• Set B: ΔH° = +80 kJ, ΔS° = +200 J mol⁻¹ K⁻¹
• Set C: ΔH° = +95 kJ, ΔS° = +220 J mol⁻¹ K⁻¹
For each set, calculate the minimum temperature (in K) above which the overall coupled process becomes spontaneous, then rank the sets from the lowest to the highest threshold temperature.