Identify the true statement about a spontaneous process. (a) A reaction that is nonspontaneous in the forward direction is spontaneous in the reverse direction. (b) Adding a catalyst will cause a nonspontaneous reaction to become spontaneous. (c) In a spontaneous process, the entropy of the system always decreases. (d) An endothermic reaction is always spontaneous.

Video transcript

Hello everyone. Today we are being given the following problem which of the following statements is correct about spontaneous processes. So let's look at a a says that all endothermic reactions are spontaneous. So this is actually going to be false. That is because when we have a positive entropy change and a negative entropy change, it is going to be non spontaneous at all temperatures. So A is not correct. Let's look at BB says for a spontaneous reaction, the entropy of the system always increases. So this is actually going to be false as well and we'll see why and then we have a negative entropy change and a negative entropy change, we're actually going to be spontaneous only at low temperatures, meaning that entropy is going to decrease. So entropy is going to decrease. So it does not always increase. So B is not correct. C says all exothermic reactions are spontaneous and this is going to be false once again. And why is that? Well, when we have a negative entropy change and a negative entropy change, as we said before, we are going to be spontaneous only at low temperatures. And so you can be non, non spontaneous at some temperatures making c incorrect. Let's look at DD says, if a reaction is spontaneous in a forward direction, the reverse redirection will be a non spontaneous reaction. And this is actually going to be true. And so we'll see that the value of G or the gives free energy of the reverse for right R is pretty much the, the gives free energy value, the forward reaction with the opposite sign. So we can say it's the opposite of the give us three energy for the forward reaction. So that's why D is going to be true. He says a non spontaneous reaction can be made spontaneous by adding a catalyst. And this is going to be false because catalysts only lower the activation energy only lower the activation energy of a reaction. And with that, we have our answer overall, I hope it's helped. And until next time.