 Let's try this problem. It says a quantity of 0.225 grams of a metal and it says the molar mass of that metal is 27.0 grams per mole liberated 0.303 liters of molecular hydrogen which was measured at 17 degrees Celsius and 741 millimeters of mercury from an excess of lark acid. To deduce from these data the corresponding equation, so the reaction equation, and write formulas for the oxide and the sulfate of M, so the metal. Okay, so I've written all the pertinent information that was given to us up here. The couple of things that you can see really quickly is that we've been given the volume temperature and pressure of the hydrogen gas, okay? We have not been given the number of moles of hydrogen gas, right? But we should be able to solve for that number of moles, okay? Remember we're trying to do a reaction equation, right? So it would be beneficial to figure out what the number of moles of hydrogen gas is first, okay? So let's do that. So let's look for the number of moles of hydrogen gas. What is that? Well, how would we set that up? We're going to do pV equals mRT, okay? So pV equals nRT for hydrogen, so we're going to solve for n, so that's going to be pV over RT, of course, and R given to us 0.0821 liter ATM per mole Kelvin. So let's figure out what's the number of moles of hydrogen. So the pressure, well, the pressure, is it in the right pressure units? No. No, we're going to have to convert it, right? 1 ATM 760 millimeters In fact, let's go through the other measurements and make sure they're in the right units. So is the volume in the right units? Leaders? Yes. Is the temperature? No. No, we're going to have to convert that, right? So plus 273 That's going to be 290 Kelvin, like that. So now that's in the right units, pressure's in the right units, so we're set, right? Okay, so let's start again. So pressure 0.975 ATM Volume 0.303 liters divided by R 0.0821 liter, ATM per one mole Kelvin, like that. And then T, of course, is 290 Kelvin. So let's cancel ATM cancels, liter cancels, Kelvin cancels, so we're going to get number of moles up on top. Okay, so what is the number of moles of hydrogen gas? Okay, so I get this number 1.24 times 10 to the negative 2 moles of H2. Okay, so you follow me to right there. Are you good? Okay to that? Okay, wonderful. So I'm going to erase some of this information specifically all of this information. We don't need it anymore. Okay, so can I just erase that? Action equations tell, the reaction equation tells us the mole ratio, okay? So that would be the mole ratio of hydrogen gas to metal, okay? So what do we know already about the reaction equation? Let's write some things that we already know about it. So what do we know? We know there's a metal, some metal reacting with excess HCl and we're going to get that metal and chlorine sticking together, right? Equals. We don't know the subscript on chlorine yet. We don't know the coefficient there. Yeah. In fact, we don't know any coefficients. Plus H2 gas, like that, which we don't know the coefficient of that either. But we do know the number of moles of H2 gas, okay? And remember the mole ratio of hydrogen to all of these other things is what we're going to need to find in order to complete this reaction equation. Okay, so let's try to find the number of moles of something else that's in that reaction equation. Well, it said that we have excess of this, so that's not going to be able to be determined right away, okay? We don't know this one, but we know some things about the metal here, right? We know the mass and the molar mass of it. So from that, we should be able to figure out the number of moles, right? So let's figure out the number of moles of the metal. So what do we got? We got 0.225 grams of the metal and the molar mass, well one mole of the metal is 27.0 grams. So we can cancel like that, you get the number of moles of the metal. So 0.225 divided by, so 0.225 divided by 27 and I get 8.33 times 10 to the negative third moles of the metal. So does that make sense there? Yep. Okay, wonderful. So now what we're going to do is figure out, well, what's the mole ratio between hydrogen gas and the metal, okay? Since this number is bigger, let's put it on top, okay? So we're going to do the mole ratio. So we'll say the ratio equals the number of moles of H2 divided by the number of moles of the metal, like that. So this I get 1.24 times 10 to the negative 2 moles of H2 divided by 8.33 times 10 to the negative 3 moles of the metal. Is that okay? So when I do this, I essentially get 1.5 moles of H2 for every one mole of the metal, like that. Okay? But we know that we can't write reaction equations with decimal points, right? So we're going to multiply both side of both top and bottom by 2, okay? To get the right mole ratio. So it's going to be for every 3 moles of H2 we're going to have 2 moles of the metal, like that, okay? We're recording, so okay? So are you cool with that? So that means we can put our coefficient there, okay, 3, and our coefficient there, 2. Okay? So if we have 3 Hs, 3 H2s, right? What are we going to put as a coefficient here? 6, right? 6. Okay, so now we've got 6 Cls, right? And we've got 2 Ms. So what are we going to do here, right? This is going to be 2 and 3, like that. Okay? Does that make sense? Okay, so that's our reaction equation. So that's one of the things that wanted us to figure out. The other thing it wants us to figure out is what is the oxide of this metal and what is the sulfate of this metal, okay? So the oxide, well, this is like from chapter, what, 2 or 3, right? So the metal plus oxygen is going to give us the oxide, right? So oxygen's charge is going to be negative 2. The metal's charge, how could we figure out what that is? Well, we look here. Does that make sense? What should it be? Those 3? Plus 3, right? So 3 plus, like that, right? So how many of these do we need? 2, 3, 3, right? So so M2O3 That's the formula for the oxide, okay? And the sulfate is actually the same because sulfate has the same charge as oxide, right? So it's going to be plus M3 plus, so we're going to need a 2 and a 3, like that. So what is the formula going to be? M2S043 Okay, does that make sense? Not as hard as it initially seemed, right? No response on that one, huh? Okay, wonderful. Any other questions on it before we kill it? No. Okay, wonderful.