don showalter. let's take a look at one of the most common reactions of all--burning. here's a piece of wood. we all know that dry wood will burn readily in air. air is about 21% oxygen. it's not burning. we've got to warm it up to get it going. let me warm it up with this match. well, i'll warm it up. the oxygen of the air reacts with the wood. there, it starts going. now, that's burning pretty well, but not really well. i wonder if it would burn any better in this 100% oxygen? well, let's see. whoa! look at that. the rate of reaction is drastically increased. what does this tell us? there's a couple of things. the rate of the reaction is increased with increased temperature. remember the match. and also, the rate of the reaction is increased with increased concentration of ingredients. remember, 20% oxygen. 100% oxygen. temperature and concentration. is there another general way of speeding reaction rate? there is, and it's employed in most reactions in the chemical industry. it involves using substances called catalysts. here i have a white powder, sodium potassium