 Okay, so let's do a lecture on figuring out the equilibrium constant using the pKa values, okay? So what we're really doing in this type of a problem is, so it's really nice they gave us both the reactants and the products, okay, and they gave us the pKa values, okay? So we've got most of the information that we need. In fact, since we're doing a little lecture, let me actually read the problem that we're going to be lecturing on. It says, given the pKa for acetic acid is 4.76, the pKa for acetylene is 25. Determine the equilibrium constant or the keq of the reaction and indicate which side of the reaction equilibrium favors by drawing in the equilibrium area, okay? So we've got to remember a couple of things in order to do this problem. First off, well, how do we figure out what the equilibrium constant is? There's an actual equation, do you remember that equation by any chance? If you don't, it's all right, I'll help you out. Products over reactants. Yeah, so it's the kA of the reactant acid over the kA of the product acid, okay? So a lot of people want to think it's the products over the reactants because you learned equilibrium constants back in GenChem too, right, that that's what it was, but if you combine, so remember this is an equilibrium reaction, it's the reactants going to the products, but the products going to the reactants too, and when you combine all of that information and then use the pKa values, or the kA values, you actually invert that equation. You can do it algebraically. So try to do it on your own just to convince yourself that that's the kA. But anyways, the kA of the reactant acid and the kA of the product acid. So what do we need to do now is figure out what is the reactant acid and what is the product acid. Well, this problem kind of helps you out, pushes you in towards that answer by showing you that the pKa of this is 4.76, the pKa of this is 25, they don't give you a pKa of this or this, neither does the reading of the problem. So it kind of tells you what's the acid and what's the base. So hopefully by now you've figured out that this is acetic acid, which is the acid base. Okay, so it might be helpful to go over to the other side and write in conjugate acid and conjugate base. But the same thing should be obvious to you that this is the acid due to the fact that it's got a pKa of this, right, so conjugate acid and conjugate base, okay. You might think, well, I don't see, you know, remember a base, what does it have to have? Usually it has lone pairs, right, or a pi bond. In this you might say, well I see a pi bond, but I think that the basic part is over here. You'd be right, this is what I was saying, if you don't remember from Jim Kim that when you have a metal non-metal bond that's actually an ionic bond, not a covalent bond, you'll forget that that carbon there actually has a lone pair and a negative charge like that. Okay, and the acetic proton is this proton here, okay. So recall that and that it'll also help you out. So when and then if you really are worried about it, I think it's right here, NA plus next to it over there, okay. And we can do the same over here, right, so hopefully you see that, does that make sense for what I've said? Okay, cool. So well you might say, well I figured all that out, what's the acid, the reactant acid and the product acid, but I have the pKa, but not the kA. So how do I get the kA from the pKa? Well remember the kA is 10 to the negative pKa, okay, so you're going to have to remember that also in order to do this. So 10 to the negative 4.76, let's do that in our calculators here, okay. And I get 1.74 times 10 to the negative 5, there's no units here, okay. Did you get something like that, okay, wonderful. So we want to do the same thing over here, right. This one's easier because it's not, it's an integer, not an integer, right, so 10 to the negative 25, we'll just write that as 1 times 10, or 1.0 times 10 to the negative 25, okay. Any problems with that one? Okay, so hopefully now it's fairly evident that we can get the keq from this point, right. Okay, so let's just get that keq. So the kA of the reactant acid, 1.74 times 10 to the negative 5, kA of the product acid, 1.0 times 10 to the negative 25, so give my calculator out, put some things in here, okay. So when I do that, I get, so it should be a big number, right, 1.78 times 10 to the 20, and that would be something you would expect, right, because when you take this 5 that's on the bottom, 25 on the bottom, bring that up, then it becomes a positive 25, you add 5, negative 5 plus positive 25, you get 20, okay. So now you've got to ask yourself, because there was an additional portion of the problem, it's a draw in the equilibrium arrows, right, so you've got to ask yourself, is this keq greater than or less than 1, way greater than 1, right, so that means it's going to go towards the product, you just draw in the equilibrium. Any questions on that one? Yeah, does it make sense? Okay, wonderful, you think you could do it on your own? Yes, sir. Okay, wonderful. I'm going to answer some more problems about that.