What does a catalyst do in a chemical reaction?

[PPonte]

What does a catalyst in a chemical reaction? I read wikipedia and the information is not very detailed to satisfy me. It basically says:

This means that catalysts reduce the amount of energy needed to start a chemical reaction. Molecules that would not have had the energy to react or that have such low energies that they probably would have taken a long time to react are able to react in the presence of a catalyst. Thus, more molecules that need to gain less energy to react will go through the chemical reaction.

 

[siddharth]

What a catalyst usually does is to lower the Energy of activation of the reaction by offering an alternate mechanism.

 

[PPonte]

What a catalyst usually does is to lower the Energy of activation of the reaction by offering an alternate mechanism.

Precisely, but in what consists this alternate mechanism?

 

[siddharth]

Precisely, but in what consists this alternate mechanism?

This link should help.
http://www.chemguide.co.uk/physical/catalysis/introduction.html#top"

 

[PPonte]

Thank you very much, siddharth. How do you find these sites? I have searched a lot.

 

[siddharth]

Thank you very much, siddharth. How do you find these sites? I have searched a lot.

That was luck. I was trying to find a link to show you how V2O5 works as a catalyst in the contact process, when I came across this site.