Especially how can i explain the experiment with a paper and 2 paperclips with the paper acting as the catalyst.
Catalysts lower the activation energy of a given chemical reaction, thus speeding it up
A catalyst is something that allows a reaction to occur but is not actually used up in the reaction. It merely provides the surface on which the chemicals react. There is a demo using two paper clips and a piece of paper. The paper is folded and the two clips are attached to the paper. When the free ends of the paper are pulled apart the two paper clips somehow overlap each other and become joined. It is a good demo for a catalyst, but I cannot explain how to fold the paper.
A catalyst acts on one material to activate it towards reaction with another material that it would not otherwise spontaneously react with (it lowers the reaction's activation barrier). For instance, the 2 paperclips may not want to react with each other, but if the paper attaches to one, it becomes more reactive and it will now clip onto the other paperclip. The catalyst then leaves (paper is detached) which is called catalyst regeneration, which goes on to activate another molecule in the same fashion. A common example is using Lewis acid catalysts to activate carbonyls by coordinating to the oxygen so that the the carbon becomes more electrophilic for attack by some nucleophile.
