 In this video you're going to learn what a catalyst is, how a catalyst works, and where catalysts are used in everyday life. Firstly, what is a catalyst? A catalyst is something which speeds up a chemical reaction, but the end of the reaction has the same mass as it had at the beginning of the reaction. This means that it is not used up in the reaction. It must, however, take part in the reaction, or we might as well not have it there at all. So, how does a catalyst work? A catalyst works by providing an alternative pathway for the reaction to occur. This alternative pathway has a lower activation energy than the pathway without the catalyst. Here are the two pathways for a reaction. The blue pathway is the energy profile for the reaction without the catalyst, and the red pathway is the energy profile for the reaction with the catalyst. You can see here that with the catalyst the activation energy is lower. As a result of the activation energy being lower, there are more molecules with the required activation energy, and so more fruitful collisions occur per second, and hence the reaction is faster. Do you know where catalysts are used in everyday life? Most manufacturing processes are exothermic for economic reasons. The heat given out is used to maintain the operating temperature of the reaction. Exothermic reactions cannot run at too high temperatures as the yield will be too low. So, as we cannot increase the rate of these exothermic reactions by having the temperatures too high, we use catalysts to increase the rate of reaction. Here are two manufacturing processes that use catalysts. Firstly, the harbour process to manufacture ammonia, most of which is used in fertilisers. In this process iron is the catalyst. The iron has potassium oxide which acts as a promoter added to increase its efficiency. And secondly, the contact process to manufacture sulfuric acid which is used to make detergents and fertilisers. Vanadium 5 oxide, sometimes known as vanadium pentoxide, is the catalyst in the contact process. Catalysts are also used in catalytic converters in vehicles. These catalysts remove toxic exhaust gases by converting them into harmless products. So, to recap, catalysts speed up chemical reactions without themselves being used up. They work by lowering the activation energy and are used in the harbour process, the contact process and in catalytic converters. Thank you.