What is Activation Energy Real Chemistry

welcome to this episode of real chemistry I'm dr. Morris today we're going to be talking about activation energy in our hideous equation so activation energy is basically the energy needed to get reaction to go and you can see it diagram down here you'll notice that in this case what we're doing is starting with the reactants and and going to the reactants and so here we're thinking about this reaction plus goes to plus and you'll notice first of all that plus drops and energy as we go down to and so that makes an exothermic reaction but before it can drop down that's got to go up this hill and that's true whether reactions exothermic or endothermic it has to go up this hill before it can drop back down and that hill and the height of that hill is called the activation energy the higher that hill is the harder it is to get that reaction to run forward now this barrier the height of it is determined by something called the Hennis equation and it's packaged into your rate laws even though we don't see activation energy and our rate laws when we write rates so let's say the rate law for this guy is this guy rate is equal to the rate constant times the concentration of and well it turns out inside that rate constant secretly tucked away is the activation energy so what we're going to do is take closer look at what determines that rate constant so here's the our tenías equation this is one way to calculate your rate constant and you'll see that on the left-hand side of the equation we have our rate constant so this guy's our rate constant and then on the right hand side of the equation we have activation energy right there so our activation energy plays role in determining our rate constant and so what that means basically is if you have really large activation energy you get smaller rate constant and slower overall rate let's take look at what all these other variables are we also have which is called the frequency factor what this is is basically measure of how often the reaction tries to go forward and then we have which is the gas constant and really important here that when you use this are you have the units of joules per mole Kelvin so it's going to be 8.3145 lastly we have temperature which is in Kelvin always and this equation when you take the frequency factor and multiply it by the exponential of these variables gives you the rate constant that frequency factor like said is the number of times the reaction tries to go forward so you can basically think about like running up hill right you might run as fast as you can up hill and if you have enough energy you get over right well if you try over and over and over and over again you're gonna have better chance of getting up over that hill up over that activation energy and so the frequency factor is basically how often do these reactants try to go through the reaction so when we think back to our graph we can picture trying to run the reaction or the frequency factor that's basically trying to run up this hill and some fraction of your molecules will have enough energy that when they try to run over they actually get over the top so the bigger the frequency factor the more often they're trying that means the bigger the and the faster the rate so the Arrhenius equation is really important equation that's this guy right that we've been talking about the whole time and it's important because it tells us what goes into our rate constant and there are just few key facts to remember about the Arrhenius equation first if you have lower activation energy that gives you higher rate this should make sense because your hill is smaller and that means getting over is easier higher temperature also means higher rate so you'll notice tucked away in our rate constant is not only our activation energy but also temperature and so rate constants are actually not constant at different imagers if you change the temperature you change the rate constant in general the higher the temperature the faster the rate now there's tons of math problems you can do with the Arrhenius equation and we're going to take look at two of those in future videos so go ahead and check out my other videos on activation energy which I'll link to below thanks for watching this episode of real chemistry please subscribe or leave any questions or comments you might have thanks for watching