 Okay, now let's look at temperature. As you know from basic kinetic theory, as you increase the temperature of a substance, the distribution of molecule speeds changes. This diagram shows the Maxwell-Boltzmann distributions for nitrogen molecules at 0°C, 1000°C and 2000°C. And you can see that as the temperature increases, there are two things that change about the distributions. First, the average speed increases. You can see this from the fact that the peak of each distribution moves further along the x-axis, so the average speed is increasing. And the second thing is that the distribution broadens out, meaning that there's a much greater range of speeds as you go up to higher temperatures. Now imagine a reaction for which the activation energy is here. Remember that each speed on this axis corresponds to a particular kinetic energy. This means that many molecules or rather any molecules with speeds greater than this will have a successful collision, while those slower than this will not. So at 0°C, essentially no molecules have the required energy, and this reaction won't happen at all. Molecules can sit there for as long as they like, and the chances that there will be a successful collision are infinitesimally small. Now if you increase the temperature of the reaction to 1000°C, you can see that the proportion of molecules with the required energy is still fairly small, but it is finite. The reaction will occur, not very fast, but it would be measurable. If you increase the temperature again to 2000°C, the proportion of molecules with sufficient energy is now much higher, and this means that the chances of a successful collision is also much higher. And if there's a greater probability of successful collisions, the reaction will go faster. So this is one of the two reasons temperature affects the rate of reaction. Changing the temperature changes the proportion of molecules that have sufficient energy to overcome the activation energy. But there is another effect of temperature, and that is that increasing the average speed of the molecules means they will also have more frequent collisions overall. So increasing the temperature is really a double whammy. The overall rate of collisions increases, and the proportion of successful collisions increases. So as before, a simple set of numbers to help you visualize what's going on. Imagine as before that you would initially have 100°C with a 30% chance of success, giving you on average 30°C, but if you increase the temperature, you might get to a situation where you had say 150°C, so you've increased the overall rate of collisions, and you now have a 50% chance of success. So your chances of successful collision have also increased. And that would then give you an overall average rate of 75 successful collisions per second. So increasing the temperature definitely increases the rate of reaction.