Grams of glucose we have, and then we're going to divide by 180.16, divide by 180.16, gives us this number, and let's see, if we So for every one mole of glucose, C6H12O6, we have 180.16 grams of glucose, C6H12O6, and this is going to get us, we get 1.52 times 1,000 is equal to, this is the number of Mass in terms of grams, you can then divide by your molar mass or you can view it as multiplying You the number of grams we have of glucose which would be 1,520 and if you have your So when you multiply these two out, this is going to give Grams in the numerator, so how many grams are there per kilograms? Well, we have 1,000 grams for every one kilogram. Is given in terms of grams, so times, we're going to want kilograms in the denominator and So if we start off withġ.52 kilograms of glucose, so that's C6H12O6, well first we can convert it to grams 'cause here, our molar mass And we could say grams of glucose, C6H12O6 per mole of glucose, C6H12O6 and then we can use this 1.52 kilograms to figure out how many moles we have. So that's equal to 180.16 grams per mole. I can only go to the hundredths place for significant figures, so 180.16. Hundredths for carbon and for oxygen, we're addingĪll of these up together so it's going to be 180. Goes to the thousandths place but we only go to the Six times 12.01 plus 12 times 1.008 plus six times 16 is equal to, and if we're thinking about significant figures here, the molar mass of hydrogen Glucose has six oxygen plus six times 16.00 grams per mole. Times 12.01 grams per mole plus 12 times 1.008 grams per mole plus every molecule of Glucose is going to be six times the molar mass of carbon plus 12 times the molar mass of hydrogen plus six times the molar mass of oxygen. The information we need from our periodic table of elements. Periodic table of elements, it has a molar mass ofġ6.00 grams per mole. Of 1.008 grams per mole, 008 grams per mole. Of 12.01 grams per mole and now we can think about Mass of a carbon atom, or what's useful, and this is where Avogadro's Number is valuable, if you have Avogadro's Number of carbons, it is going to have a mass of 12.01 grams. We've talked about it in other videos, you could view this 12.01Īs a relative atomic mass of a carbon atom, of as the average atomic Periodic table of elements, has a molar mass of 12.01 grams per mole. So if we first look at carbon, carbon, we see from this So what is the molar mass of glucose? Well to figure that out, and that's why this periodic table of elements is useful, we just have to figure out the molar mass of the constituent elements. Well then we just divide the mass of our sampleīy the mass per mole and we'll know how many moles we have. And so we have a 1.52 kilograms sample of our molecule in question, of glucose so if we can figure out the mass per mole, or another way to think about it, the molar mass of glucose, If I say a mole of something, I'm saying that's Avogadro's If I said a dozen of something, you'd say oh, that's 12 of that thing. Remember, mole is really, you can view it as a Trying to figure out the number of moles, So like always, pause this video and try to figure this out on your own and this periodic table ofĮlements will prove useful. We are asked to calculate the number of moles in a 1.52 So the final answer should be reported as 180.16 g/mol. So the 5 digit get upgraded to a 6 in the answer. Since the number we're discarding (6) is larger than 4 we round the digit it is next to up one number. So we only want the 1 and 5 digits and want to discard the 6. But because we only have two decimals digits for the 72.06 and 96.00 numbers, our answer is limited to two decimal digits. So after multiplying Sal is performing this calculation: 72.06 + 84.156 + 96.00, which mathematically would yield 180.156. For addition the sig fig rule is that we can only have as many decimal digits as do in the calculation number with the lowest number of decimal digits. You should look into sig figs in greater detail, but in this problem Sal is adding three numbers together. And the rules we use to judge how many digits are permissible are significant figures, or sig figs. But in science we are more conservative with the digits we use because of the precision of our measuring instruments. After a calculation would be able to use all the digits of the final number as our answer if we only wanted a mathematical answer. It's important to keep in mind significant figures are important for doing calculations in a science like chemistry.
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