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Rates of Reaction

What is a Catalyst?

A catalyst is a substance that will change the rate of a reaction.
A catalyst is often used to make a reaction go faster.

The catalyst does not take part in the reaction as a reactant.
It is not changed by the reaction or used up during the reaction.
It is still there in the same form when the reaction is complete.

A catalyst can be a transition metal, a transition metal oxide
(see the uses of transition metals) or an enzyme. An exception
is aluminium oxide, used for the cracking of hydrocarbons.
A substance which works well as a catalyst for one reaction
might not work well as a catalyst for a different reaction.

How does a Catalyst Work?

A catalyst works by providing a convenient surface that
enables a different route for a chemical reaction to occur.

The reacting particles on the catalyst surface collide more
frequently with each other and more of the collisions
result in a chemical reaction because the different route
provided by the catalyst has a lower activation energy.

A catalyst is often used as a fine powder so that it has
a bigger surface area per gram (see also nanoparticles).

Catalysts used to increase the rates of chemical reactions
are important in industrial processes to save energy
and reduce costs. See enzymes and the Haber process.

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