 So, let's try this problem. It says at 1000 Kelvin, a sample of pure nitrogen dioxide gas decomposes according to the following equation, so that equation that's written up there. It also gives us that the equilibrium constant Kp is 158, and analysis shows that the partial pressure of oxygen gas is 0.25 atm at equilibrium. Calculate the partial pressure of nitrogen monoxide and nitrogen dioxide in the mixture. Okay, so remember, the problem gave us Kp here, but probably the best thing for us to do to begin is to write the Kp expression. So, let's do that. So, if you guys recall, when we're writing Kp, it's going to be the partial pressures of the products divided by the partial pressures of the reactants raised to their coefficients. Okay? So, let's just write that out, and I would say you guys should write this out while I'm doing it just to make sure you get the same answers. So, partial pressure of nitrogen monoxide squared times the partial pressure of oxygen gas will coefficient, so we're not going to put a superscript there. So, to the partial, or divided by the partial pressure of nitrogen dioxide squared. Like that. Okay? So, hopefully everybody got to that point. Okay, so the other thing they told us is that we started with only nitrogen dioxide. Okay, but they didn't tell us the amount that we started with. So, that is the big problem. But, let's just say, since we like to use x for our ice tables, let's just say we started with some other variable like y. Okay? So, some amount. Okay, some pressure. Over here, we didn't start with any. So, it's going to be zero and zero there. Okay? So, we're going to set up an ice table. And since we only started with nitrogen dioxide, right, we're going to subtract. Oops. Subtract 2x from that side. Add 2x to that side. And add x to that side. So, we could say y minus 2x, 2x, and x. Okay? So, has everybody gotten to something like this? Remember, these are referring to the partial pressures. Okay? So, hopefully you guys can see, right? Well, let's erase because we know these, what these question marks are now, right? So, partial pressure of NO is going to be what? 2x, right? Partial pressure of this, NO2, y minus 2x. Okay, but look at this. Partial pressure of oxygen is 0.25 atm, but it's also x, right? So, what is going to be the partial pressure of NO? It's going to be 2 times x. Okay? So, let's just do that. So, x equals 0.25 atm. So, that equals 0.50 atm. Okay? So, we could do the other problem a number of ways, but probably the easiest would be to just plug into the Kp expression. Okay? So, let's rearrange this Kp expression to solve for the partial pressure of nitrogen dioxide. So, Kp, like that. So, let's just take that, take the square root of this side so we can raise the whole thing to the 1 half over there. So, everybody okay with doing that? Same thing as taking the square root. So, the partial pressure of NO2 is going to equal 0.50 times 0.25 divided by 158. And then we're going to take the square root of that whole thing. So, 0.5 divided by 1, 158. And that gives me 0.0, what is it, 2? So, 0.020, 18. So, partial pressure for nitrogen dioxide is 0.02 atm and the partial pressure for nitrogen monoxide is 0.5 atm. Okay? So, this one was nice because it gave us this and this. We just have to remember to do the ice table and then just plug that x in for everything. Okay? We could have done this another way, which is a little more convoluted but still equally valid. But this is a kind of a better way of doing it. Okay? Any questions on this one? Wonderful.