(d) Does the amount of work that a system can do on its surroundings depend on the path of the process?

Video transcript

Hey everyone today we're being asked which of the following options is true. And we're dealing with questions about the work performed by a system. Now let's think about this when work is being done by a system a certain amount of entropy will be created on the universe surrounding that system. For example, if we have, let's say water, we have water going from a liquid to a gas, good to a guest to a gas. The delta S of the universe will actually increase will increase. And this is because the randomness present in the universe as the liquid has become more excited is now more energetic in comparison will eventually increase the disorder or the entropy that is present in the universe. So with this in mind, if we think about it, if we have a reverse reaction that also happens or a reversible reaction then the delta S. Of the universe. The change in entropy of the universe will also revert, right? Let's try this in red. If we have the reverse reaction then delta S will revert. So by this logic we can actually say that a reversible pathway reversible pathway can accomplish the maximum amount of work because no entropy is actually lost to the universe. Because one way the reaction proceeds, entropy has increased and as it reverses the entropy decreases by the same amount. So the change in the entropy of the universe in a reversible pathway is zero. Right? So with that in mind, let's go ahead and look at our answer choices and we'll start from D. And work our way up. So it says that the amount of work performed by system on its surroundings is work dependent. Well this anti choice can immediately be ruled out. It doesn't really make sense. The work done by the system isn't dependent on the work that it outputs. It is simply a byproduct of the reaction that is happening. It is the amount of work produced by the reaction, not by the work itself. For answer choice. C. The amount of work performed by a system on its surroundings is not system dependent. Well this is also false. It is since independent right. We would need to have different systems in order to produce different amounts of work. For example. Again, looking at our water example, if we only have the forward reaction, let's say due to temperature only increasing, then the only this this part, the top part of liquid turning to gas will be part of the system. We won't be able to consider the reversible reaction in that case. So the work is actually dependent upon the system, which means that answer choice C. Is also incorrect. Now we're left to answer choices A and B. Where the work performed on the system on its surroundings as either path dependent or not dependent. And the answer to this will actually be A. And the reason for this is exactly as we described earlier when the path that is being taken either by external forces that are like temperature that are changing or pressure that is changing. If we have a reversible reaction, which is a type of pathway, that path will determine the amount of work that is performed right in a reversible reaction like this when gas becomes a liquid, the work and the change in entropy will decrease in comparison to a forward reaction. So the path dependency is a uh sorry. Path dependency is a principle or is something that work performed by a system needs to have. I hope this helps. And I look forward to seeing you all in the next one.