our discussion of moles to just atoms Moles work with molecules as well For example what is the molar mass of propanol well remember the term molar mass means the mass of one mole So I need to figure out the mass of one mole of this compound Well one mole of this compound contains three moles of carbon It contains 8 moles of hydrogen and it contains one mole of oxygen I know that one mole of carbon according to my periodic table has a mass of 12.011 g of carbon and I have 3 moles of carbon in my compound So that means in this compound I have 36 g of carbon I have eight moles of hydrogen And if I go to my periodic table I see my molar mass of hydrogen there 1.08 I see my molar mass of oxygen there We'll need it for later Notice I used a slightly different periodic table when I was setting up this example compared to what I attached to the sheet So my molar masses will be slightly different But one mole of hydrogen is 1.0079 g according to my periodic table And I have 8 moles of hydrogen So I have that many grams of hydrogen 8 g of hydrogen in my one mole of my compound I have one mole of oxygen in my compound And according to my periodic table one mole of oxygen has a mass of 16 g So my compound contains 16 g of oxygen So my compound one mole of my compound contains 36 g of carbon 8 g of hydrogen and 16 g of oxygen So if I add those masses together I discover that one mole of my compound has a mass of 60.0 95 6 g So one mole of propanol has a mass of 60.0956 0956 g and I can use this molar mass of my compound as a conversion factor For example what is the mass of 0.25 25 moles of propanol 0.25 moles is the number I'm going to start my line with I have units of moles so I'm going to place them down here where they cancel out Whatever unit I start with I want to get rid of And I know that one mole of propanol has a mass of 60.0 956 g How do I know that because that's what the numbers off the periodic table told me So I'm going to multiply everything on top divide through by everything on the bottom and I discover that 0.25 moles of propanol has a mass of 15 grams of propanol Chemistry is easy Life is hard Yes All we're doing is following that same pattern we saw last chapter Whatever unit we start with we place down here The only thing is we're using a new conversion factor And this new conversion factor is not a big deal You just look it up on the periodic chart right let's work another example going the other direction This time I've got 1.200 g of my propanol and I want to know how many moles of propanol I have Well whatever unit I start with in this case grams of propanol I place down on the bottom of my ratio so I can cancel them out So grams of propanol I know that one mole of propanol is 60.0956 g of propanol Hey moles is what I'm looking for So I must be done So I'm going to multiply everything on top divide through by everything on the bottom And I discover that 1.2 g of propanol is 0.0 0 1 9 9 6 8 moles of propanols That's an O there in case you couldn't tell All right everybody write down Kang the Conqueror even though they ruined him in the TV show Loki I mean oh my word that was a bad interpretation and explanation of Kang All right let's scroll down and look for another example Let's take a look at this example right here What is the molar mass of calcium nitrate to figure out the molar mass of calcium nitrate I know that one mole of calcium nitrate contains one mole of calcium and one mole of calcium I'm going to run to my periodic table look up that molar mass of calcium and I'll discover that one mole of calcium has a mass of 4078 g Now here's the tricky part I have a parenthesis there You're going to treat parentheses just like you would in a math class So I have nitrogen and oxygen inside my parenthesis here So I'm going to multiply those numbers by two So instead of having one nitrogen I'm going to have two nitrogens So one mole of my compound contains one mole of calcium and two moles of nitrogen I run to my periodic table and I discover that 1 mole of nitrogen is 140067 g So 14 * 2 Then 2 * 3 for my oxygen So 6 moles of oxygen And I run to my periodic table I discover that one mole of oxygen is 15.994 grams of oxygen Multiply everything and then add everything and I discover that one mole of calcium nitrate has a mass of 164.087 g So the molar mass of calcium nitrate is 164.0 087 g So I've got another conversion factor and I can have some fun with it cuz I like having fun How many moles of calcium nitrate would be in 120 g of calcium nitrate give them start start your line with the number that you're given 120 gram of calcium nitrate Place those grams of calcium nitrate where they cancel out because whatever unit we start with we want to get rid of We know the relationship between moles and grams We know that 100 and 64 087 g of calcium nitrate is one mole of calcium nitrate So we multiply everything on top divide through by everything on the bottom and we get 0.7 313 moles of calcium nitrate Chemistry is easy Life is hard Let me look up another one here Where else can I have some fun here ah let's scroll down here and take a look at another example How many molecules of propanol in 1.2 g of propanol well I have 1.200 g of my propanol I don't want grams of propanol So I'm going to place grams where they cancel out We already solved for the molar mass of propanol in a previous example And we discovered that the molar mass of propanol was one mole of propanol having a mass of 60.0956 Scroll back on example in your notes and you'll discover that's where that 60 came from So now I've gotten rid of grams I've gone to units of moles Problem is not asking for moles It's asking for molecules What's the relationship between molecules and moles what's the relationship between hammers and moles what's the relationship between cucumbers and moles 6.022 0 22 * 10 23rd of anything is how many is in a mole so one mole of propanol would contain 6.022 * 10 23rd molecules of myopropanol Right a molecule is the base unit of a compound So it's what we'd take our mole in reference to So one mole would contain 6.022 * 10 23rd molecules So now I've gotten rid of moles I have molecules which is what my question is asking for So I'm going to multiply everything on top divide through everything on the bottom and I discover that I have 1.202 * 10 22nd molecules of propanol in that 1.2000 grams of propanol All right let's take a look at a little bit of a harder question How many atoms of carbon in that 1.2000 grams of propanol there are actually two different ways you can work this problem I'm only going to work it one way because I don't want to confuse people So because if I confuse people I'd be the mad thinker Another Fantastic 4 villain 1.200 g of propanol I don't want grams of propanol So once again I'm going to place grams where they cancel out The only thing I ever know about grams is molar mass As soon as you see grams you should develop a gut reaction I've got to convert to moles We've already done the molar mass for propanol We know that one mole of propanol is 60.095 6 g of propanol So now I've gone from grams to moles Specifically I've gone from grams of propanol to moles of propanol Two different ways you can work this I have one mole of propanol Well I know that one mole of propanol contains three moles of carbon Where did that three come from right there Right One mole of my compound contains three moles of carbon So now I've gone from moles of propanol to moles of carbon Well I don't want moles of carbon So I'm going to place my moles of carbon down here where they cancel out And I know the relationship between moles and atoms by definition 6.022 * 10 23rd atoms of carbon are in one mole of carbon So now I've gotten rid of moles and I have atoms So I just multiply everything on top divide through by everything on the bottom and I get 3.607 * 10 22nd atoms And yes there's another way I could have solved this if id wanted to If I can just back up a second here If I wanted to what I could have done is I could have said all right I now have moles of propanol By definition I know that one mole of propanol contains 6.022 022 * 10 23rd molecules of propanol Then I could have said that one molecule of my propanol contains one whoops contains three atoms of carbon and that would have given me the exact same results Chemistry is easy life is hard And I think that is the last example that I need to work for you all I think everything else is simply more of the same Oh let's just real quickly work one more Let's work one more here Let's look at this one How many nanogs of sulfuric acid are in 9.24 * 10 14th molecules of sulfuric acid first thing I do I see grams and I see a compound So I'm going to run to my periodic table and I'm going to figure out the molar mass One mole of sulfuric acid contains two moles of hydrogen one mole of sulfur and four moles of oxygen So I'm going to have to run to my periodic table and look up those masses Pardon me Cough Cough Trying to think and see if I didn't do that already here Just so that I don't confuse the at home gamers I could never confuse the at home gamers because you all are too sharp All right So I run to my periodic table I find that one mole of hydrogen is 1.00794 g One mole of sulfur is 32 065 g of sulfur and 1 mole of oxygen is 16.0 00 g of oxygen 2 * 1 1 * 32 4 * 16 and I discovered that my molar mass of my sulfuric acid is 98 8.0794 g of sulfuric acid in one mole of sulfuric acid So how many nanogs of sulfuric acid are in 9.24 * 10 14th molecules of sulfuric acid so we're going to start our line with the number they gave us in the problem 9.24 24 * 10 14th molecules The only thing I know how to do with molecules is to go to moles That's the only thing I know how to do with them I know that one mole of my sulfuric acid contains 6.022 022 * 10 23rd molecules of sulfuric acid So now I've gone from molecules to moles I'm not wanting moles though So I'm going to place moles where they cancel out And the only thing I ever know about moles or the only thing I ever know about grams is the amount of grams in one mole So I go back up here where I use my periodic chart to calculate the relationship between mass and moles One mole of sulfuric acid is 98.0794 g of sulfuric acid So now I have grams of sulfuric acid as my unit because I've canceled out my moles I don't want grams of sulfuric acid However I'm wanting nanog and I know that 10^ the9th g is equivalent to one nanog So now I'm going to multiply everything on top divide through by everything on the bottom And when I do that I discover that I have 1 5* 10 to the 2 anagram or 150 anog And that's it Seriously everybody write down no more Everybody write down no more