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Ch.9 - Thermochemistry: Chemical Energy

Chapter 9, Problem 40c

The following reaction is exothermic: (c) Is the reaction likely to be spontaneous at lower temperatures only, at higher temperatures only, or at all temperatures?

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Hello. Everyone in this video. We're trying to see if this reaction here is going to be spontaneous at either low temperatures, high temperatures or at all temperatures. So again, we're given this reaction here and we're being told that this endo thermic. So let's recall that delta G is equal to delta H minus T. Delta S. So if my delta G value is less than zero, which is a negative value, this means that this reaction is spontaneous. If this delta G value is greater than zero. So of course a positive value, this means that our reaction is non spontaneous. So here we have that the delta H value is positive since the reaction is an author Mc. And our delta S value is also going to be positive since the disorder increased. We have two moles of gas Going to three moles of gas. So we have more disorder means means we have a positive delta S. Value. So for delta H, we have a positive value in delta S. We also have a positive value. This means that the reaction is going to be spontaneous at high temperatures since T delta S. Is greater than delta H. Of course this temperature multiplied by delta value will always give us a bigger value than our delta H. So all my answer choices here a through C. We see that answer choice B will most likely or will match what we just explained earlier. So my final answer for this problem is going to be answer choice B. Where it reads that the reaction is spontaneous at high temperatures