(c) In general, under which condition is ΔG°_f more positive (less negative) than ΔH°_f ? (i) When the temperature is high, (ii) when the reaction is reversible, (iii) when ΔS°_f is negative.

Video transcript

welcome back everyone. We need to determine what circumstance in general makes our change in standard gibbs free energy of formation less negative or more positive than our standard entropy change of formation. So we want to recall the following formula where our standard Gibbs free energy is equal to our standard entropy change which is subtracted from our temperature in kelvin, multiplied by our change in standard entropy. So we can see that the only factor outside of entropy gives free energy and entropy is temperature and based on a very high temperature which is multiplied by a a very negative entropy term. We would get the magnitude of an even more negative product based on these two terms being multiplied, meaning that when we take the difference of our entropy change subtracted from that even more negative term here. That is definitely going to yield a result. Where we have a change in Gibbs free energy formation that is greater than our entropy change of formation. And so our only correct answer choice to complete this example is going to be choice A which states that when the reaction has a very high temperature and a negative entropy change of formation. So if you have any questions, please leave them down below. Otherwise, I'll see everyone in the next practice video