ShmoopTube

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And here’s your Shmoop du jour, brought to you by forward reactions, when somebody

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responds to your flirting with… more flirting. [Man gives woman a bunch of flowers]

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All right, here’s today’s question:

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Which of the following is true of catalysts?

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And here are your potential answers: All right, let’s get up to speed on catalysts. [Men cycling]

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The purpose of a catalyst is to increase the rate of a reaction.

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Meaning that a substance that inhibits a reaction is not a catalyst… [Catalyst added to a beaker]

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Duh.

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So we can cross out D right off the bat.

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And how does a catalyst increase a reaction rate? [A reaction rate graph]

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By lowering the energy of an intermediate or transition state in the reaction mechanism.

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This decreases the activation energy barrier, which makes the reaction go faster.

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If only there were catalysts for doing that 8-page paper that’s due tomorrow, eh? [Woman scientist staring at a catalyst]

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Just like your car, chemical reactions can go in the forward and reverse directions. [Car travelling up and down a hill]

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The mechanism for the reverse direction is often just the forward mechanism, backwards.

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That makes sense, right? [Car reverses up a hill]

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So if a catalyst lowers the energy of a transition state, it can make both the forward and reverse

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reactions faster.

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That means that the correct answer is B. Now don’t go get that paper done. [Person orders boy to finish his paper]

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That was reverse psychology.

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Is it working? [Boy working on his paper at his desk]

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