 However, in this section, we're less interested in this than we are in the effect of these factors on the speed of a reaction. First, how do these things affect the rate? Well, as you increase the concentration of a reactant, the rate increases. As you increase the pressure of a gaseous reactant, the rate also increases. Note that increasing the pressure of a gas is much the same as increasing the concentration of an aqueous reactant. It just means you have more reactant molecules in a given volume. As you increase the temperature of a reaction, you also increase its rate. If you have a solid reactant, then the more surface area that reactant has, the faster the reaction will go. This also holds, as I said before, if you have two immiscible liquid reactants, like oil and water. And finally, if you add a catalyst, it will also make the reaction go faster. So far so good, but simply knowing something happens is not what science is all about. We need to go further. First we'll spend a couple of videos learning how to measure rates of reaction and how to classify reactions based on this information. And then we're going to get into the nitty gritty. That is, why and how do these factors affect the rate of a reaction?