how do catalysts work?
 

hey guys. please be patient with me. i'm banging my head about organic reactions. catalysts speed up reactions but don't change it. so you shouldn't get more out of a catalyzed reaction than an uncatalyzed reaction but you can! they speed up reactions but don't take part in reactions!!! how can they do this? can you explain so even dummy can understand? :eek:

I'll be patient. :D

Catalysts do take part in reactions. They are not consumed by reactions.

The theory behind this is that catalysts speed up reactions by lowering the activation energy.

In practice, we can understand it like this: molecules that might normally find it difficult to come together in the correct orientation for a reaction can find it easier to get into the correct orientation on the surface of a catalyst, like platinum for example. The molecules react more easily than normal on the platinum's surface but the platinum itself does not react. The platinum can be used over and over again.

Think of an equilibrium reaction. The rates of the forward and backward reactions are equal. If you introduce a catalyst, it won't shift the equilibrium position. The reactants and products will still be present in the same concentrations as before. They'll just be reacting forwards and backwards faster. On its own, this doesn't help any chemical production process.

What you then need to think about Le Chatelier's principle. If you remove the product from the reaction, you'll encourage more reactant to become product. Keep removing product from the reaction until you've got as much as you need. The presence of the catalyst means this happens faster than without a catalyst.

paul thanks for your very clear answer. i read it before and should have said thanks then.