11-19-2018, 02:58 PM

4. Use values of the Gibbs free energy change of formation, given below, to deduce whether the cis– or trans– isomer of but-2-ene is the more stable at 25 °C. At what temperature will the two isomers have the same stability?

I've been stuck on this question for a while. For part 1 is it trans is more stable because it has a lower enthalpy change and therefore lower energy/more stability? And for part 2 what is the difference (in the data provided) between Gf, Hf, and S and the corresponding letters in the formula ΔG = ΔH - TΔS? I understand one is formation and the other is the change, but is there a way to go from one to the other, or are they equal? I attempted plugging them in with 25 degrees (298K) but it doesn't work out. I've attempted re-arranging for T and combining the formulas (When T = T) but it hasn't worked out. Any help would be greatly appreciated! Thanks! ;D

Data:

∆Gf (kJ mol–1) ∆Hf (kJ mol–1) S (J mol–1K–1)

cis–but-2-ene 67.1 –5.7 301

trans–but-2-ene 64.1 –10.1 296

I've been stuck on this question for a while. For part 1 is it trans is more stable because it has a lower enthalpy change and therefore lower energy/more stability? And for part 2 what is the difference (in the data provided) between Gf, Hf, and S and the corresponding letters in the formula ΔG = ΔH - TΔS? I understand one is formation and the other is the change, but is there a way to go from one to the other, or are they equal? I attempted plugging them in with 25 degrees (298K) but it doesn't work out. I've attempted re-arranging for T and combining the formulas (When T = T) but it hasn't worked out. Any help would be greatly appreciated! Thanks! ;D

Data:

∆Gf (kJ mol–1) ∆Hf (kJ mol–1) S (J mol–1K–1)

cis–but-2-ene 67.1 –5.7 301

trans–but-2-ene 64.1 –10.1 296