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When you're given a quantity either mass moles or Adams
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, it's helpful to create a road map where a
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plan to change from one to another they all are
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the same amount. They're just being measured in different
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units. If you have mass, you can change
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two moles by using the molar mass. Remember,
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the molar mass is found using the periodic table and
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the molar mass. The atomic masses, the number
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below each element. So to find the molar mass
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of anything, we simply add up the molar masses
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of those. So if you have mass and you
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want to go to moles, you divide by Moeller
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Mass. If you have moles and you want to
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go to Mass, you multiply by the molar mass
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. If, instead of looking at Mass, you're
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looking at atoms or molecules or particles we use of
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a God rose number. If you have Adams and
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you want to change to moules, you can divide
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by other Godric's numbers. If you have moles to
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Adams, you multiply by offer God rose number.
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You can also go from Masto Adams, or vice
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versa, always changing two moles first. So,
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for example, we have a certain amount of moles
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of a substance six point 44 times 10 to the
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minus tube nos of mn eso for we want to
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know how many grams that equals. We're starting at
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moles and changing to mass, so we need to
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multiply by the molar mass. So we have malls
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that we multiply my molar mass to get grams to
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find the molar mass. We use the periodic table
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, and we look up the molar mass of each
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substance. Do we have the mass of MN,
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which is 54 0.938 plus the mass of sulfur,
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which is 32.0 six? It was four times the
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mass of oxygen, and this gives us a total
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Mueller math of 151 2000 grams per mole. Where
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to find the equivalent, we multiply 6.44 times,
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10 to the minus two nos. For every one
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mole, it is equal to 151.0 grams, so
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this has a mass of 9.72 grams. You could
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start instead with a mass. So, let's say
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, 15.8 kilograms of a substance F E Cielo for
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three and change it to moles. So if we
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have mass kilograms, we need to change it to
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mass in grams. And then we need to change
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two moles. And we do that by knowing that
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one kilogram is equal to 1000 grams. We use
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our Moeller Mass, so we have 15.8 kilograms.
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We change it to grams by multiplying by 1000 a
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man to change two moles we multiplied by the Moeller
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math. So one more, Um and using your
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periodic table, you find the molar mass of the
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substance to be 354 0.20 grams. So we take
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15.8 times 1000 divided by 354.20 You find that it's
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equivalent to 44.6 mol Another example in which you have
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to be careful of looking at what the question is
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asking is if we have a certain mass of a
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substance. So 92.6 milligrams, uh, NH for
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ANO, too. And we want to know how
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many Adams of nitrogen are present in this compound.
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So we have a molecule and we're looking at the
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number of nitrogen atoms using the formula, so we'll
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start off with milligrams, which we have to change
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two grams. Once we have grams, we can
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change two moles. Once we have moles of our
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compound, we can change two molecules of the compound
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and then using the chemical formula, we can find
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the number of atoms of nitrogen. So to go
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from milligrams two grams, we know there are 1000
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milligrams and everyone Graham from grams to moles will use
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the molar mass from moles to molecules we use of
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a god rose number. And then finally we used
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the chemical formula to see how many atoms there are
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in every molecule. So 92.6 milligrams for every one
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gram. There are 1000 milligrams. Using the periodic
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table, we find the molar mass and everyone mall
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of this substance has a molar mass of 92.6,
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64 64 point 06 grams. Then every mole we
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know there are 6.2 times 10 to the 23rd molecules
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. And finally, if we look at the formula
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, there are two nitrogen atoms for every one molecule
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. So by multiplying 92.6 times 6.2 times 10 to
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the 23rd times two and then dividing by 1000 times
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64.6 You see that there are 1.74 times 10 to
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the 21st Adams of nitrogen.