Rates of
Reaction Catalysts and
Energy Search Questions 
Catalysts - 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 itself does not take part in the
reaction as a reactant.
It is not changed by the reaction, it is not
used up during the reaction.
It is still there in the same form when the reaction is complete.
A catalyst is usually a transition metal, a transition metal oxide
(see uses of transition metals) or
an enzyme in
living cells. An
exception is aluminium oxide, used in 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 for the
reaction
to occur.
The reacting particles gather on the catalyst surface
and
1) collide more frequently with each other
2) more of the collisions result in a reaction between particles
because the catalyst can lower the activation energy
for the reaction.
A catalyst is often used as a powder so that it has
a bigger surface area per
gram (see also nanoparticles).
Catalysts for industrial
processes are important
to save energy and reduce
costs.
See enzymes
and the Haber Process.
Rates of
Reaction Catalysts and
Energy Search Questions
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