 So let's analyze this decomposition of mercury 2 oxide the balance equation is given to you guys on the board Let's say we did this reaction in lab Even though we would never do it because of our degrees too dangerous for you guys to be working with but as undergraduates that is Let's say we got out of this reaction 50.72 milligrams of mercury We should be able to figure out the mass of oxygen that was also Produced in this reaction. Okay, that's what we're looking to figure out. Okay. What was the mass of oxygen produced? Okay, so I'm going we're all we're going to go through the steps of this and you guys are going to tell me Does this make sense doesn't this make sense? okay, so First thing we're going to have to do is convert this from grams to moles Right why because we eventually are going to compare the moles of this to the moles of this right? And that's all mole conversion comes from the chemical reaction. Is everybody clear with that? Okay Two people are clear. Is everybody else clear? Okay, good. So if I need grams, what's the first thing I need to do? By a thousand well to convert milligrams to great right and in order to do that We're going to do baby thing baby steps not just divide by thousand We're going to show the whole conversion right so on the bottom is going to be milligrams of course and just like he said There's going to be a thousand of them and on the top what? One great right okay, and we can say if we wanted to Mercury So I'm going to do this all at once actually, but I just want to make sure everybody's okay with every step So in this step now my unit so it should be what grams of mercury right is everybody cool with that? so now I want to figure out What the number of? moles of mercury right so how do I do that? Yeah, or the atomic weight right or the Molar mass whatever you want to say in fact the molar mass is directly what you want to find okay? So how will we find the molar mass of mercury? Periodic table right we look up there. It says what 200 point five nine right? So what am I going to put at the bottom or what am I going to put at the top up here? one ball and Let's just keep it up keep saying the mercury thing okay, and on the bottom here 200 point five nine right and a mercury Everybody cool with that? Cancel cancel so what are units now? Moles of mercury right, but we wanted mass of oxygen right so now what do we have to do? Use the chemical formula right to convert from moles of mercury to moles of oxygen right? And where do we get that conversion somebody said it before the coefficients right? So we have these things here called the coefficients This one doesn't have a coefficient. What is the implied coefficient one right so? What are we going to put down here? Two moles mercury very good and up here You guys are so awesome like that So that unit now is what? Moles of oxygen is that what we wanted? No, we wanted the mass of oxygen right so how do we figure out the mass of oxygen? You got a look for the molar mass right the molar mass, so let's just calculate the molar mass of oxygen So what is it going to be so we look up there, and I'm just going to do it to two six six 16.00 grams per mole, but I have to do what? Very good multiply it by two right everybody's cool with that Why do I have to do that because there's two oxygen in every molecule of oxygen is everybody cool with that two oxygen happens? Okay, so when I do that I get 32.00 grams per mole, and you could say grams of oxygen per mole of oxygen Remember this is like the short-hand way of writing it right I could also write it like this Which might make a little more sense for what we're doing right here, okay? So what am I going to do again multiply by a ratio? What's going to be on the bottom there? One mole and in this case I'm going to say oh two right and up here Cancel cancel so that should give me the mass of oxygen that was also produced in this reaction Is everybody okay with that Okay, so let's just go through it figure out what it is so 50.72 divided by a thousand divided by two hundred point five nine divided by two multiplied by 32 Okay, so mass Well, let's put it in milligrams because it's a very small number, okay? I didn't say whether we had to put it in grams or milligrams so convert again, right? So one very good 1000 makes Okay, so multiply that by a thousand and I got so the mass of oxygen is going to be 4.0 So it's a 4 4.0 or six Milligrams Okay, so that makes sense to everybody It's just step by step by step. Okay, so that's how When you were to do all of the problems in the pre-lab Previously of course and we went over of how to do those previously Okay, so I just wanted to make sure you guys to do it step by step by step with any questions on some Okay, remember the two conversion factors that we know right molar mass and chemical equation Everybody cool with that?