 Okay, some problems are just bad luck. So, what's the root mean square speed of an argon atom at 27 degrees Celsius? Okay, so again we'll use that same formula, the root meaning squared formula. Probably you guys know that by heart by now, molar mass, and you got to remember what form of R to use of course, and in this case you're going to have to be 8.314 joules per mole kelvin. On the temperature we said was 27 degrees Celsius, so when we add that to 273.15, we're going to get 300 kelvin, and it's going to be the root mean squared speed of argon, because that's what the problem said. So, we're looking for the molar mass of argon. So, how do we figure that out? We just look up at the periodic table, all right, bye. So, let's go ahead, expand this out, and cancel our units out, just so we're making sure we're understanding what's going on, okay. So, let's take this over here, and well three, that's easy enough, R is 8.314 joules per, divide that by the molar mass, which is 39, of course the square root sign, and then let's just cancel out some of these things, okay. So, we can cancel out kelvin there, and we can cancel out moles there, right. But then we've got joules per gram, this R. So, is that normal units for speed, joules per gram, would you expect that to be speed type units that you would normally use? You might expect something else, right. So, you still got to do some conversions here, that's what this is showing, okay. So, what are those conversions we have to do? Well, we have to remember what joules actually represents, do you guys remember? So, one joule, do you remember? One kilogram meters squared per second squared, right. So, let's just do it this way, is that all right? If you don't remember, make sure you remember, because you have to know how to do that in order to do this. I don't even think one of these is on our test. This is a different class than my class though, right, yeah. Let's get that straight, since we're recording this one. Okay, so, but now we've got, you know, now we can cancel out our joules, right. Well, we've got grams down here, and we've got kilograms up here, right. So, we're going to have to change one of these in order to cancel it out, right. Because kilograms doesn't normally go into a speed unit either. So, let's just convert this to kilograms down here. Cancel both of those, and then kilograms divided by kilograms cancels there, is everybody okay with that? So, hopefully you see that what do we have? Meters squared per second squared is our units, do you guys see that? And then if you take the square root of meter squared per second squared, you're going to get meters per second. Is everybody okay with that? Okay, and that's actually called a root mean squared because you took that square root of two squares, okay. It's not really the average speed, although you might see it written as that. Okay, so, now really, it's more plug and chug, so, so my pen doesn't die. Let's just multiply this thing out three times 8.3. 400 divided by 39.95. Answer, okay, so, 433 meters per second. So, the root mean squared of argon at 27 degrees Celsius is 433 meters per second, meters per second, right? Because we're taking the square root of squared squared, okay. Are there any questions on that one? We can do another one of these if you guys like. Sir, I'll let you follow on the question, I'll tell you the second, without telling you the speed. Let's look for one, okay.