 Let's start this one then. So what is the mass of nitrogen required to occupy three liters at 100 degrees Celsius and 700 millimeters of mercury? So pressure is going to be 700 millimeters of mercury. So does anybody know the conversion factor? That's something you'll be given, 760, yeah. So if you're in process tech, you know, this is something you might want to remember, because that's a common pressure unit, 760, 180. So remember, we want to get it into ATM, right? Volume, it gives us in liters, so we're cool there. What you want to remember is these are the units you want to get it into. If you can't remember them, it's just the R units, OK? N, do we have that? No, that's what we're looking for. In fact, we're looking for N, then M, OK, right? And then T, well, it gives us 100 degrees Celsius. But we add 273 to that, because we're looking for Kelvin, 376 Kelvin, OK? So we got PV equals NRT. We're going to look for N, OK? If you're still like, I don't know what we should be looking for, because it says mass. It's the one that it didn't get, you know? So you've got to know that you've got to use that to get the one that you're looking for, OK? At least get that far, though. You'll probably get some. So let's take that. PV equals NRT. And what are we looking for, N? So isolate N, divide both sides by RT. Cancel, cancel, cancel, cancel. So our new equation is N equals PV over RT. I'm going to erase that part. And do we have all of that? P of, we haven't finished that one yet. So 700 divided by 760, 0.921. So when it's got this decimal point, after those zeros, it means it's 3 sig figs, OK? And the other thing is you never use the sig figs from the conversion factor. So we've got PV now, 0.921, ATM, V, yes, leaders, R, new piece of chalk, sorry guys. Remember, we're doing it this way. T, of course, yes. It's screaming at me because it hates PV equals NRT problems. So ATM and the numerator and the numerator and the denominator so they cancel, numerator, denominator, cancel, cancel, numerator, numerator, denominator, cancel, cancel. If you're in the denominator of the denominator, that means you go up to the top, OK? So moles goes up to the top.