 So here's another empirical formula problem for you guys. This one says vitamin C or ascorbic acid contains 40.92% carbon, 4.58% hydrogen, and 54.50% oxygen by mass. What is the empirical formula of ascorbic acid? So it doesn't tell you how much you actually analyzed. So since it's giving you percentages, the easiest way, because eventually you're going to have to convert these to masses and then to moles. I guess I should start there. But since it's giving you percentages, the easiest way for you to think about it is if you started out with a total mass of 100 grams. So if you started out with 100 grams, 40.92 mass percent of that would be 40.92 grams. Does everybody understand what I'm saying? So the best way to think about it is, in this case, your mass total of vitamin C, 100, however many, 0 is 1 gram. So if that's the case, 40.92% of 100 grams mass percent is going to be. So the mass of carbon, if that's the case, is going to be 40.92 grams of carbon. Everybody OK with me doing that? Anybody not understanding why you can do something? So I'm just going to do it to the other ones. So 4.58 grams of hydrogen, the mass of oxygen, is going to be 54.50 grams of oxygen. So again, the total mass then would be 100 grams, if you added all those up and get them. Remember, though, in the empirical formula, x, y, and z, so those subscripts of those elements are all going to be whole numbers, right? And they're all a multimole ratio of each other, a whole number multimole ratio. They're not a mass to mass ratio is what I'm saying, for those of you who are very confused right now. So in other words, we have to convert these masses to moles in order to get those x, y, and z. So how do I do that? Well, I know the molar mass from the periodic table of all of these. I'm just going to do them all at once. And I'm just putting the hydrogen and the carbon there to keep my place. It's cancel out. Well, we can cancel out. Just going to do these problems. So 4.58 divided by 4.54, sorry, moles of carbon, 3.406 moles of oxygen. So now, would anybody mind if I erase this part of the board so I can have a little bit of room? So now what I want to do is figure out what x, y, and z are. In order to do that, I have to put those mole ratios in there. So c is 3.407. h is 4.54 is 3.406. And I divide by the smallest of those numbers. In this case, 3.406 is going to be the small sum of 3.407. Remember, we're getting really close to these whole number ratios. Once you get close to them, we say, you got. So if I divide this, that's going to be close to the ratio of 1 to 1. Is everybody OK with that? So it's going to be c1h something. Let's figure that one out. 4.54 divided by 3.406. So 1.33 and o1, OK? So I'm just putting those ones there as a placeholder for right now. Remember, you don't put ones as subscripts, so in my final answer, I wouldn't put those. But hopefully, you guys see that this is not an integer, right? 3.1.33. So in order to get the empirical formula, what I would do is multiply by each integer consecutively until I get all three of them being very close to integers. Does everybody understand what I'm doing? OK, so if I multiply them all by 2, well, if I multiply them by 1, I get that. If I multiply it by 2, I get c2h2.6602, like that. If I multiply it by 3, I get c3h3, sorry, 3.99, which is essentially 4, so h4 is going to be in the empirical formula. Why is it that one? Because you have a whole number of ratios of all. So the empirical formula of this thing is c3h4o3. So again, remember, you have to get the moles from the grams. But in order to get the grams, you got to get that from the percentages. To give you percentages, it's probably best to say your total volume or your total mass of your sample initially was 100 grams, so it might take your life a lot easier. Any questions on this one? Speak now. OK.