For the gas-phase reaction A ⇌ B the following data are available: ΔH° = –80 kJ mol⁻¹…
CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics
Problem
For the gas-phase reaction A ⇌ B the following data are available:
ΔH° = –80 kJ mol⁻¹ ΔS° = –150 J mol⁻¹ K⁻¹ Eₐ (forward) = 140 kJ mol⁻¹
Consider holding the mixture for several minutes at either 300 K or 700 K.
Which statement best describes the likelihood of observing a net conversion of A to B under these two conditions?
(a) Rapid conversion at 300 K but not at 700 K, because the reaction is spontaneous only at the lower temperature.
(b) Slow conversion at both temperatures, because the large activation energy prevents appreciable reaction at either temperature.
(c) Rapid conversion at 700 K despite ΔG∘>0 there, because the much higher temperature greatly increases the reaction rate, whereas conversion is slow at 300 K.
(d) Rapid conversion at 700 K because ΔG∘ becomes more negative for an exothermic reaction at higher temperatures, whereas conversion is slow at 300 K.