Introduction to Moles

in this video we're going to talk about the basics of moles we're going to learn about what they are and we're going to talk about some of these important numbers and terms now we're going to start from the very beginning on moles here so no matter how much you know or how much you don't know about moles this video will be a great place to start so what's a mole I'm not talking about the cute little furry creatures that live underground here I'm talking about the kind of moles that are super important in chemistry so a mole is a name for a specific number of things okay a mole it's kind of like a dozen right a dozen is the name for 12 things or twelve things in a dozen now a mole is like this but it's way bigger than a dozen twelve things in a dozen in a mole there are 602 hexillion things this is 6:02 followed by 2100 and two hexillion things so a mole like a dozen is a name for certain number things there are twelve things in a dozen there are 602 hexillion things in a mole this is a gigantic number now here's one thing that confuses people about moles they forget that a mole is a name for 602 hexillion things and they think that a mole is an abbreviation for the word molecule so many people think this they seem old I think oh you mean molecule no no no if I write well I don't mean molecule I mean a group of 602 hexillion things not a molecule so there are 602 hexillion things in a mole and just like a dozen we can have a mole of anything right so we could have a dozen doughnuts which would be 12 doughnuts or we could have a mole of doughnuts which would be 602 hexillion doughnuts or hey we could have jellybeans a dozen jellybeans would be 12 jellybeans and a mole of jellybeans would be 602 hexillion jellybeans so sometimes people get freaked out about moles but just remember they're a lot like does 12 things in a dozen 602 hexillion things in a bowl you can have a mole in Donuts you can have a bowl of jelly beans and mole of cars and roll up paper clips and mole of bouncy balls just as long as it is 602 hexillion things you got a mole now let's talk a little bit about this actual number 602 hexillion this number is often referred to as Avogadro's number in honor of the italian scientist who discovered it but now check this out here write 602 hexillion this is a gigantic number 602 with 21 zeros after think about what a pain it is to deal with this number right if you're doing math by hand you got to write this out and like do your multiplication and division with 21 zeros even if you're using a calculator you got to type in all these zeros and make sure you have the right amount and then when you get your answer you got to go back and count how many zeros your answer has it's a total pain so instead of writing out 602 hexillion with all these zeros every time we want to talk about moles we tend to abbreviate this number now as you may know when we abbreviate numbers in math and science we usually use a technique called scientific notation and here's how we would abbreviate this number using scientific notation okay I got this big number 602 hexillion I find out where the decimal place would be it would be right here and now I move the decimal place until I have just one digit to the left of it okay and I count the number of spots so here's 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 and now this is my new spot because there is a six just one digit to the left of it so I moved my decimal place 23 spots to the left and that means that in scientific notation I would rewrite this number as 6.0 to times 10 to the 23rd the 23 comes from the number of spots that I moved it to the left so 6.02 times 10 to the 23rd is how we often abbreviate this gigantic number 602 hexillion when we want to write it out and use it say in math problems now this is a convenient way to write this gigantic number in scientific notation but it's also a terrible way to write it because this number 6.02 times 10 to the 23rd it looks terrifying right it's got this 10 with the exponent 6.02 times this thing it's like people see this number and they're like oh my god what do I even do in this relax it's okay 6.02 times 10 to the 23rd might look a little terrifying but just remember that it is an abbreviation for 602 hexillion that it is a brute that it is an abbreviation for this very large number here every time you see 6.02 times 10 to the 23rd just remember that it is an abbreviation for 602 hexillion okay so now we've learned what a mole is how many things are in a mole and we've learned how we can abbreviate this gigantic number 602 hexillion the last thing I want to do is give you a sense of how gigantic this number 602 hexillion how gigantic it really is okay so let's think about this mole of jellybeans that we talked about earlier 602 hexillion jellybeans which you know which you know now we can abbreviate as 6.02 times 10 to the 23rd jellybeans these are all just three ways of writing the same number okay if you had 602 hexillion jellybeans that would be as large as the entire planet Earth a mole of jellybeans would be as big as a planet Earth that is crazy think about how many jellybeans that is I mean really think about how many jellybeans it would be if your house were filled with jellybeans okay that would be gigantic think about how many jellybeans it would be if every building in your town was made only of jellybeans okay like that would be a ton now imagine how many jellybeans you have if the entire earth were made of nothing but jellybeans and that is how big a mole of something would be now we could have also a mole of Donuts which would be 600 into hexillion Donuts 6.02 times 10 to the 23rd Donuts if we had this many donuts and we stacked them on top of each other like this we had 602 hexillion Donuts and we kept making the stack this stack would reach from the earth to the Sun and back 200 billion times this stack of donuts would reach from the earth to the Sun back and forth 200 billion times again think about how many donuts we would have if we just lay donuts down like this from like your house to your school right that would be a ton of donuts now imagine going from Earth to the Sun and back 200 billion times that is how many donuts 602 hexillion doughnuts is but now here's the thing this is really interesting we're talking here about jellybeans and Donuts but a lot of times in chemistry we're talking about things that are much smaller we're talking about atoms now a mole of jellybeans would be as big as the planet Earth but a mole of atoms is much smaller here in this container I have just about one mole of sulfur atoms this yellow powder and these yellow chips are made entirely of sulfur atoms and there are about 602 hexillion sulfur atoms in this little dish here so think about this right got 602 hexillion sulfur atoms right here now 602 hexillion jellybeans would be the size of the planet Earth 602 hexillion sulfur atoms can fit in this little dish this shows us how absolutely tiny a sulfur atom is how tiny all atoms are compared to a jelly bean really a mole of these is a size a planet Earth but a mole of these little sulfur atoms can fit in this dish so when we're dealing with something as Tiny as atoms a mole doesn't actually take up that much space because the things that we're dealing with are so incredibly small that a giant number of them just isn't that big so just to review what we've talked about let's go over a few of the key points so a mole is kind of like a dozen except there are twelve things in a dozen and 602 hexillion things in a mole we can write this number in a variety of ways we can do 602 with 21 zeros after it we can call it 600 new hexillion or most commonly we can abbreviate this number in scientific notation as 6.02 times 10 to the 23rd this number here 602 hexillion is often referred to as Avogadro's number and now finally at the very end of the lesson we saw how 602 hexillion is a giant number 602 hexillion jellybeans would be the size of planet Earth but atoms are so tiny that a mole of atoms doesn't really take up that much space of 602 hexillion sulfur atoms for example is a pretty manageable size and that is an introduction to moles

Channel: Tyler DeWitt

Views: 1,678,552

Keywords: Physics (Idea), Chemistry (Professional Field), Biology (Field Of Study), physics, chemistry, biology, khan academy, Mole (SI Base Unit), mole, Avogadro Constant (Namesake), avogadro's number, Molar Mass (Dimension), atoms, 6.02

Id: wI56mHUDJgQ

Length: 10min 49sec (649 seconds)

Published: Wed Apr 23 2014