How do you tell if something is a catalyst vs an intermediate?

[John_Richey_4A]

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[Rian Montagh 2K]

A catalyst is needed as a reactant in the first step while an intermediate is made in the first step (a product) and used as a reactant in the second step.

[Catly Do 2E]

When you are looking at the elementary reactions, catalysts are in the very first step as a reactant and as a product in the very last step too. Catalysts create a different, faster pathway for the reaction, but it is not used. Intermediates are not present as reactants in the first step but are produced and consumed within the steps. They are not present as a product at the last step either.

[hanna_maillard3B]

so intermediates are always found as a product in the first reaction and reactant in the second ? and vice versa for enzymes ?

[Lydia Luong 4L]

In the first step, a catalyst is a reactant and the intermediate is a product.

[Tameen Ahmed 4C]

A catalyst is consumed by a step but regenerated by a later step. An intermediate is created by a step but consumed by a later step.

[Dong Hyun Lee 4E]

The catalyst will be in both the reactants of the first step as well as the products given in the last step. However intermediates are created between the first and the last step and are not present in the final products.

[Anita Wong 1H]

catalysts are in the reactant and intermediate is in the product side

[harshitasarambale4I]

How does this work when you have an enzyme.

[Chase Yonamine 1J]

Intermediates are consumed in the reaction

[Carine Tamamian 2B]

intermediates are consumed by the reaction, meaning they do not show up in the final rate law.
catalysts are regenerated at the end, and they do show up in the rate law.

[Bryant Vong 2G]

Intermediates are completely used up and not present by the end of the reaction

[Douglas Nguyen 2J]

A cool note I found while surfing the web was that a catalyst first shows up as a reactant and reappears as a product whereas an intermediate first shows up as a product and is cancelled out when it appears as a reactant in the next step.

[505211599]

Catalyst shows up in products and reactants but intermediated are used during the course of reaction.

[CameronDis2K]

An intermediate will cancel out in the overall reaction in the end (not appear), while a catalyst is not consumed in a reaction (appears in the beginning and reappears in the end).

[kristi le 2F]

A catalyst needs to be there in the beginning of reaction to start reaction off. The intermediate will not appear in the beginning of a reaction because it is not a reactant. It is both formed and consumed so that it does not appear in the overall chemical equation.

[MeeraBhagat]

An intermediate is formed and then used up. A catalyst is what is needed to get a reaction going (so kind of like a reactant), and then it is eventually reproduced/shows up in another step of the reaction. It is never “consumed” (not the greatest word to use but...) without reappearing.