[gear2d]

I was wondering why a system that is exothermic that has a decrease in entropy would be spontaneous at low temperatures? I thought a high temperature would work. Is there an intuitive way of seeing this? 

[luckyhooked]

It's been a few months since my thermodynamics class, but the way that I understand it, a system is at equilibrium when its free energy is as low as possible. The free energy equation is dG = dH - TdS. So even if the entropy decreases a bit , that can be compensated by the fact that the reaction is exothermic, thus dH is negative. In fact, the lower the temperature, the less of an effect the TdS term will have on the free energy. So the way I see it, as long as the entropy change is rather small and the heat released is rather large, the system would be spontaneous at low temperatures. Then again, I didn't do all that great in thermo...

[Mitch]

So if you increase the temperature, that reaction will be even more spontaneous. It would seem to jive (Yes, I just used jive in a sentence.)

[Yggdrasil]

For a reaction where ΔH < 0 and ΔS < 0, it will actually be more thermodynamically favorable at lower temperatures.  The basic way to think about it is that at low temperatures, the system wishes to minimize potential energy while at high temperatures the system wishes to maximize entropy.

[gear2d]

Thanks everyone, it makes sense now.