NwJosh

We've done an experiment on the rate of reactions using catalysts, we now have to do a right up of it and I'm stuck on explaining how the catalysts worked in the experiment i know that the help break chemical bonds in reactant molecules and provide a 'different pathway' for the reaction, but how do they do it. The experiment was using 10cm3 potassium iodide solution, 10cm3 sodium thiosulfate solution, 5cm3 starch solution add the catalysts and then add 20cm3 of potassium peroxodisulfate solution I've been told by my teacher that it is something to do with the shape of the molecule and the catalysts, but i cant remember exactly what she said, or that i understood it.