[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:03.05,Default,,0000,0000,0000,,Let's talk about a concept that probably
Dialogue: 0,0:00:03.07,0:00:06.98,Default,,0000,0000,0000,,confuses chemistry students the most on some level.
Dialogue: 0,0:00:06.99,0:00:09.28,Default,,0000,0000,0000,,But on some level it's also one of the simplest concepts.
Dialogue: 0,0:00:09.30,0:00:10.87,Default,,0000,0000,0000,,And that's the idea of a mole,
Dialogue: 0,0:00:12.05,0:00:13.59,Default,,0000,0000,0000,,which in chemistry is different
Dialogue: 0,0:00:13.65,0:00:15.37,Default,,0000,0000,0000,,that the thing digging up your backyard,
Dialogue: 0,0:00:15.51,0:00:19.14,Default,,0000,0000,0000,,or the thing you want to get removed from your left eye.
Dialogue: 0,0:00:19.27,0:00:21.80,Default,,0000,0000,0000,,A mole in chemistry is just a number.
Dialogue: 0,0:00:21.82,0:00:23.77,Default,,0000,0000,0000,,It's just a number,
Dialogue: 0,0:00:23.79,0:00:28.20,Default,,0000,0000,0000,,and the number is 6.02 times 10 to the 23.
Dialogue: 0,0:00:28.22,0:00:29.73,Default,,0000,0000,0000,,So it's a very huge number.
Dialogue: 0,0:00:29.74,0:00:31.75,Default,,0000,0000,0000,,And this is also called Avogadro's number.
Dialogue: 0,0:00:31.77,0:00:34.56,Default,,0000,0000,0000,,Maybe I will do a video on Avogadro.
Dialogue: 0,0:00:35.02,0:00:38.63,Default,,0000,0000,0000,,Avogadro's number
Dialogue: 0,0:00:39.79,0:00:41.92,Default,,0000,0000,0000,,But that's all you need to know.
Dialogue: 0,0:00:41.94,0:00:43.46,Default,,0000,0000,0000,,A mole is just a number.
Dialogue: 0,0:00:43.48,0:00:47.31,Default,,0000,0000,0000,,There are kind of more Byzantine definitions of a mole.
Dialogue: 0,0:00:47.32,0:00:49.20,Default,,0000,0000,0000,,This actually is not
Dialogue: 0,0:00:49.21,0:00:51.59,Default,,0000,0000,0000,,-- actually, let me copy and paste it from Wikipedia.
Dialogue: 0,0:00:51.61,0:00:55.43,Default,,0000,0000,0000,,This is Wikipedia's definition of a mole.
Dialogue: 0,0:00:55.45,0:00:58.43,Default,,0000,0000,0000,,And you hopefully at the end of this video
Dialogue: 0,0:00:58.44,0:00:59.74,Default,,0000,0000,0000,,you'll see that they're equivalent.
Dialogue: 0,0:00:59.74,0:01:01.42,Default,,0000,0000,0000,,But if you're just getting exposed to the concept,
Dialogue: 0,0:01:01.43,0:01:07.14,Default,,0000,0000,0000,,this to me, it's just not an easy concept.
Dialogue: 0,0:01:07.16,0:01:10.40,Default,,0000,0000,0000,,Basically, "a mole is defined as the amount of substance
Dialogue: 0,0:01:10.42,0:01:16.06,Default,,0000,0000,0000,,of a system that contains as many elemental entities
Dialogue: 0,0:01:16.07,0:01:19.86,Default,,0000,0000,0000,,as there are atoms in 12 grams of carbon 12."
Dialogue: 0,0:01:19.88,0:01:24.49,Default,,0000,0000,0000,,Well, I just told you that a mole is 6.02 times 10 to the 23.
Dialogue: 0,0:01:24.51,0:01:26.46,Default,,0000,0000,0000,,So if you just take the last part,
Dialogue: 0,0:01:26.48,0:01:30.85,Default,,0000,0000,0000,,atoms in 12 grams of carbon 12.
Dialogue: 0,0:01:30.87,0:01:39.93,Default,,0000,0000,0000,,So that means that there are 1 mole of carbon 12
Dialogue: 0,0:01:39.95,0:01:42.38,Default,,0000,0000,0000,,-- let me write it like that -- carbon 12.
Dialogue: 0,0:01:42.40,0:01:57.73,Default,,0000,0000,0000,,There are 1 mole of carbon 12 atoms in 12 grams of carbon.
Dialogue: 0,0:01:57.75,0:01:59.93,Default,,0000,0000,0000,,And so that's why a mole is useful.
Dialogue: 0,0:01:59.95,0:02:02.26,Default,,0000,0000,0000,,So I could have just instead of writing 1 mole,
Dialogue: 0,0:02:02.28,0:02:06.35,Default,,0000,0000,0000,,I could have replaced this as there's 6.02 times 10
Dialogue: 0,0:02:06.36,0:02:12.08,Default,,0000,0000,0000,,to the 23 carbon atoms, carbon 12 atoms in 12 grams of carbon.
Dialogue: 0,0:02:12.09,0:02:13.25,Default,,0000,0000,0000,,How do you figure that out?
Dialogue: 0,0:02:13.26,0:02:15.43,Default,,0000,0000,0000,,Or I guess, what else does this mean?
Dialogue: 0,0:02:15.45,0:02:17.37,Default,,0000,0000,0000,,I mean, we just added in carbon,
Dialogue: 0,0:02:17.39,0:02:19.57,Default,,0000,0000,0000,,they said it's the amount of substance of any molecule,
Dialogue: 0,0:02:19.58,0:02:22.96,Default,,0000,0000,0000,,if you convert between atomic mass units and grams.
Dialogue: 0,0:02:22.98,0:02:24.61,Default,,0000,0000,0000,,This I find very confusing.
Dialogue: 0,0:02:24.62,0:02:26.62,Default,,0000,0000,0000,,How can we apply this in other places?
Dialogue: 0,0:02:26.64,0:02:29.01,Default,,0000,0000,0000,,So the first thing to realize is a mole is just a way
Dialogue: 0,0:02:29.03,0:02:32.39,Default,,0000,0000,0000,,of translating between grams and atomic mass units.
Dialogue: 0,0:02:32.41,0:02:35.34,Default,,0000,0000,0000,,One carbon 12 atom is what?
Dialogue: 0,0:02:35.36,0:02:37.72,Default,,0000,0000,0000,,What's its mass number?
Dialogue: 0,0:02:37.74,0:02:38.99,Default,,0000,0000,0000,,It's 12.
Dialogue: 0,0:02:39.01,0:02:41.70,Default,,0000,0000,0000,,That's why it's called carbon 12 instead of carbon 14.
Dialogue: 0,0:02:41.71,0:02:46.46,Default,,0000,0000,0000,,So its mass is 12 atomic mass units.
Dialogue: 0,0:02:46.47,0:02:50.78,Default,,0000,0000,0000,,So if you have something that has a mass of 12 atomic mass units
Dialogue: 0,0:02:50.80,0:02:52.21,Default,,0000,0000,0000,,and you have a mole of them,
Dialogue: 0,0:02:52.49,0:02:55.64,Default,,0000,0000,0000,,or you have 6.02 times 10 to the 23 of them,
Dialogue: 0,0:02:55.66,0:03:01.53,Default,,0000,0000,0000,,all of those atoms combined will have a mass of 12 grams.
Dialogue: 0,0:03:01.55,0:03:03.81,Default,,0000,0000,0000,,So another way to think about it is
Dialogue: 0,0:03:04.07,0:03:13.74,Default,,0000,0000,0000,,1 gram is equal to 1 mole of atomic mass units.
Dialogue: 0,0:03:13.76,0:03:16.62,Default,,0000,0000,0000,,I'll write amu's like that.
Dialogue: 0,0:03:16.64,0:03:22.16,Default,,0000,0000,0000,,Or you can write 1 gram is equal to 6.02
Dialogue: 0,0:03:22.17,0:03:26.20,Default,,0000,0000,0000,,times 10 to the 23 atomic mass units.
Dialogue: 0,0:03:26.22,0:03:28.56,Default,,0000,0000,0000,,And the reason why this is useful
Dialogue: 0,0:03:28.57,0:03:30.70,Default,,0000,0000,0000,,-- and it's kind of addressed in this Wikipedia definition there
Dialogue: 0,0:03:30.71,0:03:33.80,Default,,0000,0000,0000,,-- is it helps us translate between the atomic world
Dialogue: 0,0:03:33.82,0:03:36.35,Default,,0000,0000,0000,,-- where we deal with atomic mass units and we deal with,
Dialogue: 0,0:03:36.36,0:03:37.97,Default,,0000,0000,0000,,oh, we've got an extra neutron now,
Dialogue: 0,0:03:37.98,0:03:41.13,Default,,0000,0000,0000,,let's add one to our atomic mass number
Dialogue: 0,0:03:41.15,0:03:43.07,Default,,0000,0000,0000,,-- and translating between that atomic world
Dialogue: 0,0:03:43.12,0:03:45.46,Default,,0000,0000,0000,,and our everyday world where we deal in grams.
Dialogue: 0,0:03:45.47,0:03:47.12,Default,,0000,0000,0000,,And just so you know, a gram is still
Dialogue: 0,0:03:47.14,0:03:50.71,Default,,0000,0000,0000,,a pretty small amount of mass.
Dialogue: 0,0:03:50.72,0:03:52.46,Default,,0000,0000,0000,,It's 1/1,000 of a kilogram.
Dialogue: 0,0:03:52.48,0:03:54.07,Default,,0000,0000,0000,,A kilogram is about 2 pounds.
Dialogue: 0,0:03:54.09,0:03:56.50,Default,,0000,0000,0000,,So this is about 1/500 of a pound.
Dialogue: 0,0:03:56.51,0:03:58.13,Default,,0000,0000,0000,,So this is not much.
Dialogue: 0,0:03:58.15,0:04:02.01,Default,,0000,0000,0000,,So there's a ton of atoms in a very small amount of
Dialogue: 0,0:04:02.03,0:04:06.58,Default,,0000,0000,0000,,-- in 1 gram of carbon, or at least in 12 grams of carbon,
Dialogue: 0,0:04:06.60,0:04:10.79,Default,,0000,0000,0000,,you have a ton of atoms. You have 6.02 times 10 to the 23.
Dialogue: 0,0:04:10.81,0:04:12.16,Default,,0000,0000,0000,,And just to hit the point home,
Dialogue: 0,0:04:12.17,0:04:13.80,Default,,0000,0000,0000,,I probably should have talked about this in the atom.
Dialogue: 0,0:04:13.82,0:04:15.97,Default,,0000,0000,0000,,This is a huge number.
Dialogue: 0,0:04:15.98,0:04:22.11,Default,,0000,0000,0000,,To maybe visualize it, if you think of -- I was told that
Dialogue: 0,0:04:22.13,0:04:25.29,Default,,0000,0000,0000,,in the diameter of a hair, if this is a hair
Dialogue: 0,0:04:25.30,0:04:27.64,Default,,0000,0000,0000,,and this is diameter of the hair,
Dialogue: 0,0:04:27.66,0:04:32.89,Default,,0000,0000,0000,,if you go this way there 1 million carbon atoms.
Dialogue: 0,0:04:32.91,0:04:35.47,Default,,0000,0000,0000,,1 million carbon atoms that way.
Dialogue: 0,0:04:35.48,0:04:41.55,Default,,0000,0000,0000,,Or if you were to take an apple
Dialogue: 0,0:04:41.56,0:04:45.18,Default,,0000,0000,0000,,and you were to try to figure out what fraction,
Dialogue: 0,0:04:45.20,0:04:48.78,Default,,0000,0000,0000,,if you were to make one of the atoms of an apple
Dialogue: 0,0:04:48.80,0:04:50.14,Default,,0000,0000,0000,,-- and obviously,
Dialogue: 0,0:04:50.15,0:04:52.75,Default,,0000,0000,0000,,an apple has a bunch of different types of atoms in it
Dialogue: 0,0:04:52.76,0:04:53.83,Default,,0000,0000,0000,,-- but if you were to take one of the atoms
Dialogue: 0,0:04:53.85,0:04:55.51,Default,,0000,0000,0000,,and make it the size of the apple,
Dialogue: 0,0:04:55.53,0:04:58.30,Default,,0000,0000,0000,,then the apple would be the size of the earth.
Dialogue: 0,0:04:58.32,0:05:00.76,Default,,0000,0000,0000,,So an apple atom is to an apple
Dialogue: 0,0:05:00.91,0:05:03.00,Default,,0000,0000,0000,,as an apple is to the earth.
Dialogue: 0,0:05:03.02,0:05:06.31,Default,,0000,0000,0000,,So these are obviously-- it's hard for us
Dialogue: 0,0:05:06.33,0:05:08.78,Default,,0000,0000,0000,,to even process things of this size.
Dialogue: 0,0:05:08.80,0:05:12.13,Default,,0000,0000,0000,,When you just have one gram of
Dialogue: 0,0:05:12.15,0:05:14.77,Default,,0000,0000,0000,,-- well, let's say you have 1 gram of hydrogen.
Dialogue: 0,0:05:14.78,0:05:22.92,Default,,0000,0000,0000,,1 gram of hydrogen. 1 gram of hydrogen.
Dialogue: 0,0:05:22.93,0:05:24.59,Default,,0000,0000,0000,,If you have 1 gram of hydrogen,
Dialogue: 0,0:05:24.61,0:05:29.50,Default,,0000,0000,0000,,that means you have 1 mole of hydrogen.
Dialogue: 0,0:05:29.51,0:05:31.15,Default,,0000,0000,0000,,How do I know that?
Dialogue: 0,0:05:31.17,0:05:34.40,Default,,0000,0000,0000,,Because hydrogen's atomic mass number is 1.
Dialogue: 0,0:05:34.42,0:05:39.09,Default,,0000,0000,0000,,So in general, if you just take any element
Dialogue: 0,0:05:39.12,0:05:41.69,Default,,0000,0000,0000,,-- so what is the mass of,
Dialogue: 0,0:05:41.72,0:05:45.16,Default,,0000,0000,0000,,let me just pick, 1 mole of aluminum?
Dialogue: 0,0:05:45.17,0:05:54.17,Default,,0000,0000,0000,,So if I were to take 6.02 times 10 to the 23 aluminum atoms,
Dialogue: 0,0:05:54.18,0:05:56.17,Default,,0000,0000,0000,,what is the mass of that collection?
Dialogue: 0,0:05:56.18,0:06:00.72,Default,,0000,0000,0000,,Well, each of them have an atomic mass number of 13.
Dialogue: 0,0:06:00.74,0:06:08.07,Default,,0000,0000,0000,,So it's 13 amu's-- I don't have to put the s there
Dialogue: 0,0:06:08.09,0:06:11.74,Default,,0000,0000,0000,,-- times six point
Dialogue: 0,0:06:11.75,0:06:14.36,Default,,0000,0000,0000,,-- well, I won't write that way, actually.
Dialogue: 0,0:06:14.38,0:06:15.70,Default,,0000,0000,0000,,That'll probably just confuse you.
Dialogue: 0,0:06:15.71,0:06:18.05,Default,,0000,0000,0000,,The easy way to think about is if you have a mole of an atom,
Dialogue: 0,0:06:18.08,0:06:21.10,Default,,0000,0000,0000,,you take its mass-- I was taking its atomic number,
Dialogue: 0,0:06:21.12,0:06:23.93,Default,,0000,0000,0000,,that's not good-- you take its mass number.
Dialogue: 0,0:06:23.95,0:06:26.07,Default,,0000,0000,0000,,In this case let's say it's 27.
Dialogue: 0,0:06:26.09,0:06:30.37,Default,,0000,0000,0000,,So we're dealing with aluminum 27.
Dialogue: 0,0:06:30.38,0:06:34.97,Default,,0000,0000,0000,,You take its mass number, and if you have 1 mole of it,
Dialogue: 0,0:06:34.98,0:06:41.69,Default,,0000,0000,0000,,then the mass of that will be 27 grams.
Dialogue: 0,0:06:41.71,0:06:44.42,Default,,0000,0000,0000,,So that literally, when you have one mole of an atom
Dialogue: 0,0:06:44.44,0:06:48.47,Default,,0000,0000,0000,,it's a direct translation between its mass number and grams.
Dialogue: 0,0:06:48.48,0:06:53.80,Default,,0000,0000,0000,,1 mole of iron, let's say iron 56--
Dialogue: 0,0:06:53.81,0:06:55.77,Default,,0000,0000,0000,,there's obviously many isotopes or iron
Dialogue: 0,0:06:55.78,0:06:58.31,Default,,0000,0000,0000,,-- let's say we're dealing with iron 56.
Dialogue: 0,0:06:58.33,0:06:59.85,Default,,0000,0000,0000,,You normally don't hear it like that,
Dialogue: 0,0:06:59.86,0:07:02.48,Default,,0000,0000,0000,,but let's say we're dealing with the isotope of iron
Dialogue: 0,0:07:02.50,0:07:04.18,Default,,0000,0000,0000,,that has a mass number of 56.
Dialogue: 0,0:07:04.20,0:07:11.41,Default,,0000,0000,0000,,So if I have 1 mole of this, 1 mole of this atom right here,
Dialogue: 0,0:07:11.42,0:07:14.38,Default,,0000,0000,0000,,that's going to have a mass of
Dialogue: 0,0:07:15.20,0:07:16.62,Default,,0000,0000,0000,,-- the math isn't difficult here
Dialogue: 0,0:07:16.64,0:07:23.05,Default,,0000,0000,0000,,-- 56 grams. Right? And if you think about it,
Dialogue: 0,0:07:23.06,0:07:24.95,Default,,0000,0000,0000,,how many atomic mass units is this?
Dialogue: 0,0:07:24.97,0:07:30.93,Default,,0000,0000,0000,,Well, this is 56 atomic mass units per atom.
Dialogue: 0,0:07:30.95,0:07:32.60,Default,,0000,0000,0000,,Then you have a mole of those, so you have
Dialogue: 0,0:07:32.62,0:07:37.83,Default,,0000,0000,0000,,6.02 times 10 to the 23 times 56 atomic mass units.
Dialogue: 0,0:07:37.84,0:07:38.98,Default,,0000,0000,0000,,And then you divide it
Dialogue: 0,0:07:39.00,0:07:41.75,Default,,0000,0000,0000,,by the number of atomic mass units per gram.
Dialogue: 0,0:07:41.77,0:07:43.46,Default,,0000,0000,0000,,And you end up with 56 grams.
Dialogue: 0,0:07:43.47,0:07:44.84,Default,,0000,0000,0000,,But the easy way to think about it is
Dialogue: 0,0:07:44.86,0:07:46.92,Default,,0000,0000,0000,,you just take whatever the mass number is.
Dialogue: 0,0:07:46.93,0:07:49.69,Default,,0000,0000,0000,,If you have silicon, if you have a mole of silicon,
Dialogue: 0,0:07:49.70,0:07:52.20,Default,,0000,0000,0000,,a mole of silicon will have a mass
Dialogue: 0,0:07:52.40,0:07:53.24,Default,,0000,0000,0000,,-- I don't want to say weight
Dialogue: 0,0:07:53.31,0:07:54.84,Default,,0000,0000,0000,,because this should apply to any planet
Dialogue: 0,0:07:54.97,0:07:56.32,Default,,0000,0000,0000,,-- of 28 grams.
Dialogue: 0,0:07:56.36,0:08:04.22,Default,,0000,0000,0000,,What about 2 moles of silicon? 2 moles of silicon.
Dialogue: 0,0:08:04.25,0:08:05.36,Default,,0000,0000,0000,,And I'll write its mass number.
Dialogue: 0,0:08:05.38,0:08:10.50,Default,,0000,0000,0000,,Let's say silicon has a mass number of 28.
Dialogue: 0,0:08:10.51,0:08:12.89,Default,,0000,0000,0000,,Two moles of silicon.
Dialogue: 0,0:08:12.91,0:08:15.77,Default,,0000,0000,0000,,Well, 1 more would have a mass of 28 grams,
Dialogue: 0,0:08:15.79,0:08:23.89,Default,,0000,0000,0000,,so 2 moles is going to have a mass of 56 grams.
Dialogue: 0,0:08:23.91,0:08:29.96,Default,,0000,0000,0000,,If I were to say, let's say I had 4 moles of oxygen,
Dialogue: 0,0:08:29.96,0:08:32.39,Default,,0000,0000,0000,,which has a mass number of 16.
Dialogue: 0,0:08:32.41,0:08:34.60,Default,,0000,0000,0000,,What is the mass of that?
Dialogue: 0,0:08:34.61,0:08:37.32,Default,,0000,0000,0000,,This is a huge number of oxygen atoms
Dialogue: 0,0:08:37.33,0:08:38.76,Default,,0000,0000,0000,,-- what would be the mass of that?
Dialogue: 0,0:08:38.78,0:08:44.10,Default,,0000,0000,0000,,Well, it would be 4 times-- 1 mole of oxygen
Dialogue: 0,0:08:44.12,0:08:46.95,Default,,0000,0000,0000,,would have a mass of 16 grams,
Dialogue: 0,0:08:47.06,0:08:49.87,Default,,0000,0000,0000,,so 4 moles has 64 grams.
Dialogue: 0,0:08:52.32,0:08:55.40,Default,,0000,0000,0000,,It's confusing because we're not used to using a word
Dialogue: 0,0:08:55.42,0:08:58.36,Default,,0000,0000,0000,,like moles as a number, but all it is, is a number.
Dialogue: 0,0:08:58.38,0:09:00.35,Default,,0000,0000,0000,,And the easy way to think about is that it lets us
Dialogue: 0,0:09:00.36,0:09:06.42,Default,,0000,0000,0000,,translate between this atomic mass unit number and grams.
Dialogue: 0,0:09:06.43,0:09:08.44,Default,,0000,0000,0000,,And you say, well, how do I get that many grams?
Dialogue: 0,0:09:08.46,0:09:12.02,Default,,0000,0000,0000,,Well, I have to have 6.02 times 10 to the 23 carbon atoms
Dialogue: 0,0:09:12.03,0:09:16.30,Default,,0000,0000,0000,,for that collection of carbon to have a mass of 12 grams.
Dialogue: 0,0:09:16.32,0:09:18.47,Default,,0000,0000,0000,,That's all that mole means.
Dialogue: 0,0:09:18.48,0:09:19.46,Default,,0000,0000,0000,,It's just a number.
Dialogue: 0,0:09:19.64,0:09:21.36,Default,,0000,0000,0000,,And I encourage you to kind of play around
Dialogue: 0,0:09:21.45,0:09:22.80,Default,,0000,0000,0000,,with a lot of what we talked about.
Dialogue: 0,0:09:22.80,0:09:24.21,Default,,0000,0000,0000,,Because it's super important
Dialogue: 0,0:09:24.27,0:09:25.14,Default,,0000,0000,0000,,to have the intuition behind moles,
Dialogue: 0,0:09:25.14,0:09:27.78,Default,,0000,0000,0000,,otherwise, you'll get confused later on
Dialogue: 0,0:09:27.78,0:09:29.79,Default,,0000,0000,0000,,when we start getting into energies
Dialogue: 0,0:09:29.86,0:09:31.47,Default,,0000,0000,0000,,in terms of it requires kilojoules per mole,
Dialogue: 0,0:09:31.47,0:09:34.33,Default,,0000,0000,0000,,and what is the energy of this reaction
Dialogue: 0,0:09:34.33,0:09:35.31,Default,,0000,0000,0000,,and all that type of stuff.
Dialogue: 0,0:09:35.31,0:09:37.97,Default,,0000,0000,0000,,So just really try to make sure
Dialogue: 0,0:09:37.97,0:09:38.53,Default,,0000,0000,0000,,you digest this as well as possible.
Dialogue: 0,0:09:38.53,0:09:40.29,Default,,0000,0000,0000,,And let me know if you don't
Dialogue: 0,0:09:40.29,0:09:42.59,Default,,0000,0000,0000,,and I'll maybe make another video on this
Dialogue: 0,0:09:42.59,0:09:43.06,Default,,0000,0000,0000,,because it's so important.