 Okay, cool. So let's do this problem that's up there on the board. A gas sample has a volume of 2.50 liters when it's at a temperature of 30 degrees Celsius and a pressure of 1.80 ATM. So what do we already know about this sample? We know what? B1, right, is what? 2.50 liters, right? T1, do we go back? 30 degrees Celsius, and remember we want to put these into Kelvin. So how do we do that? 273, and what is that equal? 303 Kelvin. What else do we know about the initial state of the gas? P1, we know it's P1, too. So notice this one, three things are going to change. This is called the combined gas law. You're actually combining two of the other gas laws from previously. You can see that V, P, and T are all in this gas law. So P1 here, what did we say it was, was 1.80 ATM. So then it says, what volume and liters will the sample have if the pressure is increased to 3.00 ATM and the temperature is increased to 100 degrees Celsius? So what are we looking for? B2, right? Do we know T2? Yeah, or what's next? P2 is what? 3.00 ATM, right? And that changed, right? And T2 is going to be 100, but are we going to leave it in degrees Celsius? So we're going to add the 273 to it. So what do we get? 373 Kelvin. So this we were looking for. So V1 changed, right? Our T changed, T changed, and P changed, okay? So this is the combined gas law, okay? So more than one, more than two variables, okay? Two types of variables. So let's do it how we normally do it. PV equals NRT divided by PV equals NRT. We're going to put 1 at the top, 2's at the bottom, right? Did P change? Yes, so we're going to leave that. Did V change? Yes, so we're going to leave that. Did N change? No. No. Cancel? Did R change? No. No, it never changes. Did T change? Yes. Okay, so our new, I'm just going to erase because I think we got it, right? Can I just erase like that and then say our new law is going to be P1, V1, T1, P2, V2, T2, right? So what is the variable that we want to isolate? V2. What would be a good thing to do? Flip it over, right? Flip it over. Why? Because V2 is in the bottom, right? So let's just flip it, okay? So what do we get if we flip it? We get P2, V2, right? Divided by P1, V1. Is that cool, everybody? I know, right? Bashing your head against the wall, that's what I think. What about on this side? T2 over T1, right? Okay, so is the variable isolated? No, right? What do we got to do? We can do it all in one fell swoop if we want to, right? We can multiply it by what? 1, V1, and also divide it by what? V2, right? Sorry, P2, yeah. What are we looking for again? P2, right? And if we do that to that side, we're going to have to do it to this side, right? So let's just do that. So P1, V1 over P2, right? Is everybody okay with doing that? Does everybody understand why we did that? So if we did that, we can do this. Cancel, cancel, V1 cancel, cancel, P2 cancel, cancel, right? Does anything cancel over here? No. So what's our new equation? V2 equals T2 P1 V1 divided by T1 T2, right? Is everybody cool with that? So now what do we do? Just do it, yeah, well you should, right? So T2 is going to be 373 Kelvin. So P1, P1, 180, ATM, V1, where is it? 2.50 liters.