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Quantitative Information from Chemical Equations

In chemistry, a chemical equation is a symbolic representation of a chemical reaction. The chemical reaction is an expression of the conversion of one set of chemical substances to another. Both reactants and products are usually given in the form of chemical species. Chemical equations are not sentences in a natural language. They are guidelines for balancing chemical equations, and they show the relationship between chemical species.


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Video Transcript

so from a chemical equation, if you're given a mass or a model of one molecule, you confined theme Mueller Mass. The moles, the number of particles or the number of atoms than any other molecules in the equation. And whenever you're working with these problems, you want to make sure that your stoke geometry is correct. So S O. E com tree is very important because the number of rules that you're working with will change the values drastically on DSO. For this video will be answering a couple of questions that are based off of the combustion of sugar based on the fact that you are given a known quantity of sugar. And so for these problems, we'll be working with the fact that you are given to 0.77 g of shirt. And so, for the first problem, we want to figure out the number of molecules of co two that you make in your product set. So to do this, we need to figure out the number of moles, love, sugar, the number of moles of carbon dioxide and from their use. Avocado is never to calculate the number of molecules. So first, let's start with figuring out the number of bulls. Fortunate. So from our previous problems, we know that sugar has a molar mass of 342.2 g per mole. So let's use this to solve this problem. So again, whenever you're using dimensional analysis, you want to start with what you're given and then manipulates this so that you get the moles that you want. So here we want to multiply this. I think so. So the grams are on the bottom and the bulls are on the top. And when we do this, grams with cancel, so then you're left with moles. And when you do at the math, you should get zero point 008 09 walls of shirt. So now we figure out the bowls of sugar, but we need the moles of carbon dioxide. So then you need to multiply this by 12 to get the number of moles for carbon dioxide which ends up being 0.0 971 moles. And now you want Thio Europe, the number of well, girls LCU to. So then you can use this by multiplying this by ABBA God Rose number which is 6.0 to to times 10 to the 23rd particles. And in this case, we're working with molecules of CO two, so we can just write molecules to be more specific over one more. So then, if you do that out, you should get 5.8 five times on to the 22nd molecules. Terrible molecules we'll see. And this should be your final answer to this problem. So here we show that if you're given the mass for one of the molecules in the equation, you can use it to find the number of molecules for another molecule in the same equation. Now, for the second part, we want to figure out the total number of hydrogen atoms on the product side. So we'll be doing something very similar to the top. Except this time we have an additional step where you want to figure out the number of hydrogen atoms, um, that you made on the product side. So here we're going to start this very similarly eso again. You have to 0.77 g. Sure, and you want to apply this to multiply this with the more mass in this way. So This is technically dividing the grams by the molar mass to obtain your moles. And in this case, we have 11 for the U coefficient instead of 12. So you'll be multiplying this by 11, and we should end up with is zero point 08 he nine. Sorry, that's not right. Um, Shana, with 0.890 malls of each too well and then from there, you want to multiply this, my Alma God Rose number to make sure that the units cancel out and again instead of just writing particles, we can write molecules, be more specific. And when you do this, the moles should cancel out. And what you're left with is I'm going to write the answer here 5.36 times 10 to the 22nd molecules of water. And it's important to know that that's not what you're looking for. We have one more step, and so we want to figure out the number the total number of hydrogen atoms on the product side. Then we need to multiply that number by two because for every one molecule of water, there are two atoms of hydrogen, and so your final answer should be 1.7 times turn to the 23rd bottoms of hydrogen. And so, for the last problem, we can figure out the number of grams of a molecule and the chemical reaction given the number of grams for a different molecule and the chemical reaction, Um and so here will be starting out the problem the same way. So you want to always figure out the number of moles before you calculate different quantities. And so again, we start off with dividing the grams by the molar mass off what you were given to get your moles. And here, like the problem, we live. We're working with water. So then you won't apply this value by 11 to get 0.890 And then from there right now are units are in moles of water and you actually want to get grams, then two that will use dimensional analysis. And so when you do this by multiplying this by theme Mueller mass of water So the molar mass of water eyes about 18 grams Permal. So then when we do out the calculation, we should get one point 60 g off water. And so from this video, we've learned that by starting out with the mass, uh, one component off one molecule, we can figure out the number of molecules or any other molecule that is in the same equation. In addition, we can also figure out the number of atoms and the equation based on this information. And in addition, we can also figure out the number of grams for any of the molecules in the chemical equation just from the mass of one molecule. And so when you do these problems, it's really important to keep your units very clear because you always want to cancel out units to obtain the ones that you want by using specific ratios. And you always want to keep in mind that whenever you want thio, get number of particles, or if your answer involves getting that you always want to use avocados number. And whenever you're looking for Grams, you want to make sure that you include some kind of Moeller mass in your final equation. And whenever you're working with atoms, you want to make sure that you are indeed working with atoms and not just molecules. Eso again, you want to make sure that your units are clear and your ratios are clear to make sure you don't make any silly mistakes.