A catalyst can be seen as any substance that increases the rate of reaction by decreasing your energy of activation and also not being consumed in the process. Here we have a catalyzed versus an uncatalyzed reaction being displayed in terms of an energy diagram. Remember, in our energy diagram we have our reactants in the beginning, our products at the end. The difference between the two lines represents the overall change in energy of the chemical reaction.
And then if we take a look here, we have at the top of this first hill is our transition state for it. And at the top of this hill is our transition state. The difference between a transition States and the reactant line gives us our activation energy. Remember, a catalyst lowers your energy of activation. If we take a look at the first red curve, we can see that its activation energy is pretty high. So it's safe to assume that this is the energy of activation for our uncatalyzed reaction. So here we'd say that this is EA uncapped.
Now when we add a catalyst, the energy of activation is expected to go down. So the line in blue represents the addition of our catalyst. So this would be EA cap per catalyzed. So remember the height of the activation energy has a direct impact on the speed of the reaction. The higher the activation energy, the longer it takes for my reactants to basically climb and scale this hill to slide down and become a product.
So the red line here we say since it's higher up and higher activation energy, it would take longer for us to make our products the catalyzed one. Since the activation energy is smaller, we expect the reactants to have an easier time getting up this hill and sliding down to make our products. So keep in mind this is what a catalyst does. It lowers our energy of activation so that our reactants can more easily become products.