WEBVTT
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So in the previous video, we calculated the molecular
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weight based on the atomic mass units of each atoms
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in the molecule on DSO. In this video,
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we'll be talking about how to calculate the molar mass
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of a molecule and given the number of grams,
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we can figure out the number of bowls. Um
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and so the molar mass of a molecule is calculated
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in a very similar way to the molecular weight.
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Specifically, we can still use the same values on
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the periodic table for each item. So, for
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example, for hydrogen, it is one atomic mass
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unit. But it is also 1 g Permal and
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likewise for something like oxygen. Um, it's atomic
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. Fascinated is 16.0 and it is also 16.0 g
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per mole. And so the difference between the molecular
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weight and the molar mass is that molecular weight is
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in atomic mass units and Mueller Mass is in grams
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per mole. And so we usually use fuller masses
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. Um, when trying to understand the information that
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we get from chemical reactions one, so today,
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while we going over the commission of share like we've
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done before, and I'll show you, um,
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the different information that we can get just given grams
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for a particular molecule. Eso again, Let's write
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out the combustion of sugar. So sugar has a
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chemical formula of C 12, H 20 to 11
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, and in combustion reactions, the fuel will react
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thio oxygen gas to create some number of carbon dioxide
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molecules, as well as a number of war molecules
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. And again, When you're running chemical reactions,
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you want to make sure that your reaction is balanced
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. So it's a balance. This we'll need 12
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oxygen molecules, 12 carbon dioxide molecules and 11 warm
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of molecules. And so, before we want Thio
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, figure out the number of moles. We have
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to be given a mass first, which I will
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give it later. But let's try to figure out
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the Mueller mass of each molecule to start with.
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So for carbon, um, this would be 12.1
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g per mole for hydrogen. This would be one
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point 00 8 g Permal, and for oxygen,
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this would be 16.0 g per mole. So,
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yeah, I'm using the same method as before.
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We can calculate the Mueller masses of each molecule in
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this equation. Eso In the case for sugar,
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this would be 12 times 12.1 plus 22 times 1.8
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plus writing on the second line because I have no
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space 16.0 and this should equal 342 0.2 grams per
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mole. And if you do this for oxygen,
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that would be too times 16.0 which will equal,
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um 32 transfer more and for CNN to that would
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be too time 16 on and adding its Wall 0.1
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. So we got 32 waas 12 his 44 point
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one grams per mall for water to type 1.8 waas
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question. And that would be 18 point 02 g
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Permal, right? So I'm just going thio box
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this so it's easier to see Okay, grift.
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And I'm just going to use those squiggly lines so
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we know that we're talking about different molecules. So
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now we've calculated the Mueller masses or all the molecules
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in our equation. So now if we're given a
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mass for one molecule, we can calculate the number
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of bulls for that molecule. So, for example
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, Let's say you're given 5.36 g of sugar.
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Using this information, we can calculate the number of
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moles kosher using the molar mass eso using dimensional analysis
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. We see that if we set up this equation
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like so um so if we set up this equation
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like so we have our given value or the value
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that we're starting with, which is 5.36 g and
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we can use eventual analysis to get moles so we
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can set up the smaller mass so that moles are
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on top and 3 g are on the bottom.
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So if we cited up in this manner, we
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see that the grams canceled ever left with bulls.
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So then, um, in 5.36 g of sugar
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, we can calculate this so that we obtain zero
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point 015 66 moles of shirt. And if we
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based the number of most of the other molecules based
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on this one given piece of information, we can
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calculate the number of wolves for everything else. And
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so if we wanted to calculate the moles of oxygen
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, you would multiply this by 12, because right
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now, the coefficient for sugar is one. And
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so if it were something else, like if this
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were to, then you would have to divide this
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by two to kind of normalize it and then use
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that number to calculate the other most house. In
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this case, the coefficient is one. And so
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we can just multiply this, um, by 12
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for oxygen to get the number of moles. And
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when you do this, you get 0.18 79 malls
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, Hello to you. Then you get 0.1879 moles
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O C 02 Then you get 0.172 to 6 balls
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of H 20 And so here we have learned that
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by calculating the molar mass for all the molecules and
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given a piece of information like a mask, you
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can figure out the moles of one molecule as well
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as the number of moles. Were all of the
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other molecules in your chemical equation