What is the difference between an exothermic reaction and an e...

Question

What is the difference between an exothermic reaction and an exergonic reaction?

Accepted Answer

Welcome back everyone. In this example, we need to choose the statement from the following statements, differentiating an exo agonic reaction from an exothermic reaction. We have choices A through D which discuss either the negative or positive values of entropy and gibbs free energy change for exotic and exothermic reactions as well as the spontaneity. Let's start by differentiating what we know about exothermic reactions versus exo exer agonic. So beginning with exothermic reactions recall that in such a reaction energy is going to be released, meaning that heat is a product and because heat is being released in the form of energy. A second point is that there is a negative entropy change. Recalled that entropy change discusses the amount of heat released or absorbed at constant pressure by a reaction. And so in this case, a negative entropy change means that heat is lost. Now, we're going to differentiate from an exer agonic reaction. So for an exotic reaction, free energy is released, recall that the term free energy describes energy available to do work. So the free energy being released and an exotic reaction is released during the course of the reaction and is used to perform the work of things like powering a cellular process in a biological system where we can think of in terms of chemistry for electrochemical cells where free energy of a spontaneous reaction is released in a redox process to drive the flow of electrons through a circuit. So with that in mind, we should also note a second point that gibbs free energy change is going to be negative for an ex ergo reaction, meaning that the reaction is going to be spontaneous. Mhm So there's no need for an input of additional energy because the reaction will instantly occur. So based on what we've outlined, we can agree that the energy being discussed is what differentiates an exothermic reaction from an ex ergodic reaction. So again, exon is with regard to the free energy or energy available to do work based on the free energy change of a chemical reaction. While an exothermic reaction is just with regard to the heat energy that is being exchanged either absorbed or released in a reaction. And we would observe that for example, when the bonds of products are being formed. So let's make another note that all exothermic reactions our eggs are and that's because a release of heat will decrease the overall free energy of a system. However, with this note, although all exothermic reactions are exon, not all exotic reactions are exothermic. And an example that we can note for that is such as when we have an increase in entropy for a reaction which would correlate to a higher amount of free energy being released but does not directly correlate to a release of heat. So overall, based on what we've outlined, observing our answer, choices, choice A begins to state that an exotic reaction is non spontaneous and has a positive value for gibbs free energy change delta G. While an exothermic reaction releases heat to the surroundings and has a positive value for delta H entropy change. And this is all incorrect. So choice A is a false statement and we would rule it out as our answer. Then we have choice B an ex Ergodic reaction is non spontaneous and has a negative value for gives free energy. So as we state, an ex Ergodic reaction should be spontaneous, that part is incorrect so far, while an exothermic reaction releases heat to the surroundings and has a negative value for entropy change. While the second part of the statement is correct, we would rule out choice B because it is overall a false statement. And then we have choice C. An ex Ergodic reaction is spontaneous and has a negative value for GPS free energy change while an exothermic reaction releases heat to the surroundings and has a negative value for entropy change. And this is all true. So choice C looks like a great answer. And then we have choice D an exotic reaction is spontaneous and has a positive value for gives free energy change. So that is incorrect, it should be negative while an exothermic reaction releases heat to the surroundings and has a negative value for entropy change. So we would rule out choice D and that means that choice C is going to be our final answer to complete this example. I hope that this made sense and let us know if you have any questions.

What is the difference between an exothermic reaction and an exergonic reaction?

Key Concepts

Exothermic Reaction

Exergonic Reaction

Energy Transfer

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