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Given an exam question, would we be told in the problem what would be the catalyst in a reaction or would we have to determine that ourselves? And if we do have to determine that ourselves, how would we go about determining that? I'm still a bit confused from lecture how that's determined and in how it differs from an intermediate reactant.
You can tell by looking at the steps and identifying which molecule didn't change. Intermediates are like "in between" molecules so their structure changes. But catalysts don't chemically change in a reaction. If you see that they're the same on both the reactant and product side of a reaction then it's most likely a catalyst.
When you determine the overall reaction by combining the different steps, catalysts are usually in product and reactant side. Intermediates, however, are not in the overall equation because they are made and destroyed in the process.
Catalyst do not change. They just "provoke/speed up" the reaction to happen. It will be part of the reactant for that, then also part of the product. It is said to be "regenerated" but not used up. Only intermediates get destroyed since they are only formed and but later on canceled.
If I'm not mistaken, in a set of reaction steps, you will find a catalyst to be first found on the reactants side, then subsequently found on the products side in the next step and vice versa for intermediates. This is because catalysts are not "used up" in a reaction but intermediates are, which is why they are first produced as products, and then later used up and disappear in a later step.
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