Calculate the percent composition by mass of each element in Al(OH) 3 . Use at least three significant figures.

Alright. So for the compound barium hydroxide we need to calculate each element's mass percentage. Okay. Alright. You answer using at least three significant figures. So we're going to go ahead and find that out first. We need to take a look at the compound and actually figure out its molar mass. So barium hydroxide, we have one barium. If we take a look at the product table, the mouse of barium is 137 Points g per mole. Then for oxygen notice that we have oxygen and then it's brackets, there's two. That means we have two oxygen's in total and oxygen Lee 16 g per mole. That gives us 32 g per mole. And then for hydrogen the same thing, it's being multiplied by that too. So we have two hydrogen in total times it's smaller mass from the periodic table. And that's 2.02. Alright, so we're going to go ahead and add these three numbers. That will give us the molar mass of barium hydroxide, which is 171. grams per mole. So what we just found was the total mass of this compound. Now we can go ahead and calculate the mass percentages of each of the elements because mass percent. It's just going to equal to the mass of whatever it is that we're finding the percent for divided by the total mass. Right? And total mass here is going to be the molar mass and then times 100. Alright, so let's go ahead and do that. So for barium It's percentage is going to be it's mouse the mouse herbarium is 1:37 . g divided by the total mass, which is 171. g or g from Old Times 100. Right? So that will give us 80.15%. I'm going to actually delete this. We don't need that and move this over. Alright, so forbearing it is 80.15%. Alright, so now for hydrogen We are going to look. So we have 2.02 g for hydrogen again divided by the total mass And then times 100 And that gives us 1. percent. Okay. And lastly, for the oxygen, I'm going to write it over here. So for the oxygen we have 32g of oxygen, divide again by the total mass of the compound, Which is the molar mass of the compound and in times And that gives us 18.68%. So of course when you add all of these percentages, they should equal to 100%. Right? Because this compound is only made up of these elements and they should all um add up to 100 now, you might be a little bit off just depending on the rounding that we've done but it should be pretty close to 100. Alright. Alright folks, if you have any questions, let us know, but we'll see you next video