Clicked Gallery

What is a catalyst?

Highlighted from a real textbook passage. Explained by Clicked.

Used in a sentence

University Course Reader · STEM

Adding a catalyst raised the reaction rate substantially while leaving the yield unchanged.

The reader highlighted one word in a textbook passage. Clicked broke down the concept “catalyst” into plain English:

Explained in three depths

Same facts, different vibe — Slang mode 😎

The Clicked way

●○○

Overview

A catalyst is a substance that speeds up a chemical reaction without being used up. It opens an easier route, one that needs less energy to get started. Speed is the only thing it changes. It cannot alter what forms, or how much of it forms. But a reaction that would take a thousand years is a reaction that never happens, so speed decides a great deal.
●○○

Overview

A catalyst is stuff you add to make a reaction go fast, and it comes back out untouched. So a pinch of it keeps working all day instead of being spent. All it changes is speed, which sounds minor until you remember that a reaction slow enough is a reaction that never happens. 😎

A quick take — often all you need.

●●○

Detail

Hydrogen peroxide sitting in a bottle turns into water and oxygen over months. Add a little manganese dioxide and the same change finishes in seconds. The manganese dioxide is still sitting there afterwards, ready to do it again. Molecules need a certain amount of energy before they can react at all, which is called the activation energy. A catalyst offers a route where that requirement is lower, so far more molecules clear it every second. Why not just heat the mixture, which also speeds reactions? Because heat speeds up everything in the vessel, including the reactions ruining your product, and heating industrial equipment is expensive. What a catalyst cannot do is change the outcome, since the same products form in the same amounts. A reaction too slow to observe is still a reaction that does not happen, which is why the large majority of manufactured chemicals pass through one.
●●○

Detail

Hold a piece of plain bread in your mouth and it slowly turns sweet, which is a mildly unsettling thing to learn about yourself mid-sandwich. That is an enzyme in your spit taking the starch apart, and it is a catalyst. It survives the job, so each molecule of it moves straight on to the next piece of starch. Every reaction has a starting hurdle called activation energy, and this stuff opens a route where the hurdle is lower, so far more of it happens per second. Could you not just turn the heat up? Your body cannot, and heat would rush every other reaction in there as well. Living things run on picky reusable helpers instead, and so does most of industry. The limit is that it cannot change what you finish with, or how much of it. Only how fast. 😎

Want more? One click digs deeper.

●●●

Analogy

Two towns sit either side of a mountain. The only route climbs over the summit, so almost nobody makes the trip. Dig a tunnel and the traffic increases enormously. The destination is the same town, and travellers still walk there themselves. What the tunnel cannot do is put a town where there was never one.
Deepest level reached.
●●●

Analogy

A group chat where nobody will book anything. Then one person posts a link with an actual date, and suddenly six people are in. They did not pay for the trip or invent the destination, and they are still in the chat next month doing the same thing. All they did was make starting easy. If the trip had been genuinely impossible, no link would have saved it. 😎
Deepest level reached.

Unfamiliar concept? A real-world example makes it click — fresh analogies on tap.

AI explanations may contain errors · Not professional advice

Formal definition — The same term, explained the usual way

A catalyst is a substance that increases the rate of a chemical reaction by providing an alternative pathway with a lower activation energy, and which is regenerated at the end of the reaction cycle rather than consumed. It affects the kinetics of a reaction but not its thermodynamics, and therefore alters neither the position of equilibrium nor the achievable yield, though a sufficiently slow uncatalysed reaction may be practically unobservable.

Want Clicked to explain terms like “catalyst” directly in your browser — including on PDFs?

Add to Chrome — Free

50 free Explanations · No credit card required