Composition

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##### Top Chemistry 101 Educators ##### Stephanie C.

University of Central Florida  ##### Allea C.

University of Maryland - University College

### Video Transcript

of a. So now we have two elements or compounds nitrogen dioxide and touch a nitrogen or die nitrogen toucher oxide. So here are the molecular formulas for each. And just by looking at these two compounds, you can tell that they have the same empirical formula of n 02 But we have to prove that we can, and we will prove that by assessing the mass percent of each element in making sure that it's the same for each element. So if the nitrogen so first, what? ISS math percent? Last percent, basically is the weight for mass of each element in the compound and is ratio to the total mass of the coal compound, but for one more of that compound. So that's the key thing here for one mole of each heart pound, and it's, you know, a mass thing. So let's think about this. So one mole of national outside is one mole of nitrogen and two moles of oxygen. So this is you know, this might not be intuitive for you, but you should try to think about it a bit. So last percent is the, um, the total mass ratio of one mole of the compound. So it's one more the mass of one mole of each element over the massive one mole of the whole compound and further nitrogen. It's one more. And for oxygen. That's two moles, because one mole of this compound, as two moles of oxygen for everyone won't of and for vanish into oxide. It would be two moles, two moles of nitrogen. So yes, there would be two moles of nitrogen and formals of oxygen would represent one more off compound. And when we're finding the mass percent of like done estrogen, two moles imagine represents one elemental or one compound of the whole total compound. So first, let's find the first thing that we then need to find is the mass of each element. Let's just if you can't tell, divide the screen to to a little parts here. So the to find mass we know that mass is moles multiplied by molar mass Mallomars that we will find on any product people. So we have so one. The molar mass of nitrogen is basically 14 and the molar mass of oxygen is 16 grams per mole. If we just, you know, approximate this Yeah, and this year will give us the mass that we'll find being masked. This here will get was the mess of one more a cop out. So the body of these in the calculator we know what this is. 14 grams and 32 rooms. Uh, accident. So then that is this a total, you know, mass of n 02 or one mole to being 46 Gramps. And if we do the same thing over here and the total mass for one more of dire introgen touch oxide you that most of these over mullah masses we find to be 92. Okay, so then now we can use thes numbers to give us the mass percents of each element. So here, nitrogen, it would be 14 over 46 grams and for oxygen would be 32 32/46. Gramps, just by looking at this chart over here. And these are all grams, grams, grams to give us. He's a 30.44% nitrogen and 69.55 percent. That's a six 69.55 percent oxygen. Nothing nuts were diagnosed in touch oxide on on the other side No, no. This is for nitrogen dioxide. Sorry. On the underside for a dinosaur in touch oxide. We have here different numbers. 28 grams over the 92. So four grams, which will also still give us a percent of 30.44 and then for oxygen would be 16 times for I mean, just hopefully I'm not 64/92 grams, which will give us again, Uh, mass percent 69 a 0.55 So, as you can see, even in these very two in these two different compounds, since they have the same empirical formula, the mass presents for each element is the same. We have to make sure we find their correct number, mulls for one more of compound. McMaster University

#### Topics

Composition

##### Top Chemistry 101 Educators ##### Stephanie C.

University of Central Florida  ##### Allea C.

University of Maryland - University College