On an exam I got this question: [PLAIN]http://img849.imageshack.us/img849/5732/spontaneity.png [Broken] but at the time I had no idea how to answer it. I still don't really know if I can answer it. I can explain it mathematically with the equation: ΔG = ΔH - TΔS seeing as a spontaneous reaction requires a negative change in G and therefore if the sign of ΔH and ΔS are different then temperature will be a determining factor as to whether or not ΔG will be negative. I have no idea what I would need to plot on a graph though. As for examples of reactions of each type I suppose I needed to have a few example reactions memorised.