[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.71,0:00:04.20,Default,,0000,0000,0000,,Like the concept of the mole,\Nbalancing equations is one of
Dialogue: 0,0:00:04.20,0:00:06.70,Default,,0000,0000,0000,,those ideas that you learn in\Nfirst-year chemistry class.
Dialogue: 0,0:00:06.70,0:00:09.25,Default,,0000,0000,0000,,It tends to give a lot of\Nstudents a hard time, even
Dialogue: 0,0:00:09.25,0:00:12.43,Default,,0000,0000,0000,,though it is a fairly\Nstraightforward concept.
Dialogue: 0,0:00:12.43,0:00:13.97,Default,,0000,0000,0000,,I think what makes it difficult\Nis that there's a
Dialogue: 0,0:00:13.97,0:00:15.35,Default,,0000,0000,0000,,bit of an art to it.
Dialogue: 0,0:00:15.35,0:00:17.79,Default,,0000,0000,0000,,So before we talk about\Nbalancing chemical equations,
Dialogue: 0,0:00:17.79,0:00:18.92,Default,,0000,0000,0000,,what is a chemical equation?
Dialogue: 0,0:00:18.92,0:00:20.66,Default,,0000,0000,0000,,Well here's some examples right\Nhere, and I have some
Dialogue: 0,0:00:20.66,0:00:22.18,Default,,0000,0000,0000,,more in the rest\Nof this video.
Dialogue: 0,0:00:22.18,0:00:24.75,Default,,0000,0000,0000,,But it essentially just\Ndescribes a chemical reaction.
Dialogue: 0,0:00:24.75,0:00:25.72,Default,,0000,0000,0000,,You've got some aluminum.
Dialogue: 0,0:00:25.72,0:00:30.60,Default,,0000,0000,0000,,You have some oxygen gas or a\Ndiatomic oxygen molecule.
Dialogue: 0,0:00:30.60,0:00:32.86,Default,,0000,0000,0000,,And then you end up with\Naluminum oxide.
Dialogue: 0,0:00:32.86,0:00:34.85,Default,,0000,0000,0000,,And you would say, ok, fine,\Nthat's an equation.
Dialogue: 0,0:00:34.85,0:00:35.83,Default,,0000,0000,0000,,It looks nice.
Dialogue: 0,0:00:35.83,0:00:38.70,Default,,0000,0000,0000,,I have my reactants, or\Nthe things that react.
Dialogue: 0,0:00:38.70,0:00:40.24,Default,,0000,0000,0000,,These are the reactants.
Dialogue: 0,0:00:40.24,0:00:42.51,Default,,0000,0000,0000,,And then I have the products\Nof this reaction.
Dialogue: 0,0:00:42.51,0:00:44.09,Default,,0000,0000,0000,,What's left there to do?
Dialogue: 0,0:00:44.09,0:00:45.40,Default,,0000,0000,0000,,Well you have a problem here.
Dialogue: 0,0:00:45.40,0:00:47.77,Default,,0000,0000,0000,,The way I've written it right\Nnow, I have one atom of
Dialogue: 0,0:00:47.77,0:00:51.55,Default,,0000,0000,0000,,aluminum plus two atoms\Nof oxygen, right?
Dialogue: 0,0:00:51.55,0:00:53.70,Default,,0000,0000,0000,,They're bonded to each other,\Nbut there's two atoms of
Dialogue: 0,0:00:53.70,0:00:54.25,Default,,0000,0000,0000,,oxygen here.
Dialogue: 0,0:00:54.25,0:00:59.27,Default,,0000,0000,0000,,One molecule of diatomic oxygen,\Nor one molecule of
Dialogue: 0,0:00:59.27,0:01:01.54,Default,,0000,0000,0000,,oxygen, but they have two\Noxygen atoms here.
Dialogue: 0,0:01:01.54,0:01:05.03,Default,,0000,0000,0000,,And when you add them together,\NI have two atoms of
Dialogue: 0,0:01:05.03,0:01:07.02,Default,,0000,0000,0000,,aluminum and three\Natoms of oxygen.
Dialogue: 0,0:01:07.02,0:01:09.55,Default,,0000,0000,0000,,So I have a different number of\Naluminums on both sides of
Dialogue: 0,0:01:09.55,0:01:10.51,Default,,0000,0000,0000,,this equation.
Dialogue: 0,0:01:10.51,0:01:12.47,Default,,0000,0000,0000,,On this side, I have\None aluminum.
Dialogue: 0,0:01:12.47,0:01:14.81,Default,,0000,0000,0000,,On this side, I have two\Naluminums. And then I have a
Dialogue: 0,0:01:14.81,0:01:15.85,Default,,0000,0000,0000,,different number of oxygens.
Dialogue: 0,0:01:15.85,0:01:17.58,Default,,0000,0000,0000,,On this side, I have\Ntwo oxygens.
Dialogue: 0,0:01:17.58,0:01:19.36,Default,,0000,0000,0000,,And on that side, I have\Nthree oxygens.
Dialogue: 0,0:01:19.36,0:01:22.70,Default,,0000,0000,0000,,So balancing equations is all\Nabout fixing that problem, so
Dialogue: 0,0:01:22.70,0:01:24.99,Default,,0000,0000,0000,,that I have the same number of\Naluminum on both sides of the
Dialogue: 0,0:01:24.99,0:01:28.24,Default,,0000,0000,0000,,equation, and the same number\Nof oxygens on both sides.
Dialogue: 0,0:01:28.24,0:01:30.20,Default,,0000,0000,0000,,So let's try to do that.
Dialogue: 0,0:01:30.20,0:01:31.96,Default,,0000,0000,0000,,I'll do it in orange.
Dialogue: 0,0:01:31.96,0:01:35.10,Default,,0000,0000,0000,,So I said I have one aluminum\Nhere and I have
Dialogue: 0,0:01:35.10,0:01:36.60,Default,,0000,0000,0000,,two aluminums there.
Dialogue: 0,0:01:36.60,0:01:39.13,Default,,0000,0000,0000,,So maybe a simple thing is just\Nto put a two out here.
Dialogue: 0,0:01:39.13,0:01:42.99,Default,,0000,0000,0000,,So now I have two aluminums on\Nthis side and I have two
Dialogue: 0,0:01:42.99,0:01:44.29,Default,,0000,0000,0000,,aluminums on this side.
Dialogue: 0,0:01:44.29,0:01:45.40,Default,,0000,0000,0000,,The aluminums look happy.
Dialogue: 0,0:01:45.40,0:01:47.06,Default,,0000,0000,0000,,Now let's look at the oxygen.
Dialogue: 0,0:01:47.06,0:01:49.88,Default,,0000,0000,0000,,Here I have two oxygens on the
Dialogue: 0,0:01:49.88,0:01:51.08,Default,,0000,0000,0000,,left-hand side of the equation.
Dialogue: 0,0:01:51.08,0:01:52.90,Default,,0000,0000,0000,,And on the right-hand\Nside of the equation
Dialogue: 0,0:01:52.90,0:01:54.28,Default,,0000,0000,0000,,I have three oxygens.
Dialogue: 0,0:01:54.28,0:01:55.56,Default,,0000,0000,0000,,What can I do here?
Dialogue: 0,0:01:55.56,0:01:58.96,Default,,0000,0000,0000,,Well if I could kind of have\Nhalf atoms, I could just
Dialogue: 0,0:01:58.96,0:02:01.84,Default,,0000,0000,0000,,multiply this by\None and a half.
Dialogue: 0,0:02:01.84,0:02:03.91,Default,,0000,0000,0000,,1.5.
Dialogue: 0,0:02:03.91,0:02:06.19,Default,,0000,0000,0000,,1.5 times 2 is 3.
Dialogue: 0,0:02:06.19,0:02:09.60,Default,,0000,0000,0000,,So now I have three oxygens on\Nboth sides of this equation
Dialogue: 0,0:02:09.60,0:02:12.18,Default,,0000,0000,0000,,and I have two aluminums on both\Nsides of the equation.
Dialogue: 0,0:02:12.18,0:02:13.21,Default,,0000,0000,0000,,Am I done?
Dialogue: 0,0:02:13.21,0:02:15.94,Default,,0000,0000,0000,,Well, no, you can't have half\Nan atom, or one and
Dialogue: 0,0:02:15.94,0:02:17.13,Default,,0000,0000,0000,,a half of an atom.
Dialogue: 0,0:02:17.13,0:02:18.27,Default,,0000,0000,0000,,That's not cool.
Dialogue: 0,0:02:18.27,0:02:20.48,Default,,0000,0000,0000,,So what you do is you just\Nmultiply this so that you end
Dialogue: 0,0:02:20.48,0:02:21.14,Default,,0000,0000,0000,,up with whole numbers.
Dialogue: 0,0:02:21.14,0:02:23.23,Default,,0000,0000,0000,,So let's just multiply\Nboth sides of this
Dialogue: 0,0:02:23.23,0:02:26.07,Default,,0000,0000,0000,,whole equation by two.
Dialogue: 0,0:02:26.07,0:02:37.70,Default,,0000,0000,0000,,And we have four aluminums plus\Nthree oxygens yields-- we
Dialogue: 0,0:02:37.70,0:02:40.21,Default,,0000,0000,0000,,multiplied everything\Nby two-- two
Dialogue: 0,0:02:40.21,0:02:45.09,Default,,0000,0000,0000,,molecules of aluminum oxide.
Dialogue: 0,0:02:45.09,0:02:47.78,Default,,0000,0000,0000,,Now, you might have been tempted\Nat some point in this
Dialogue: 0,0:02:47.78,0:02:50.95,Default,,0000,0000,0000,,exercise to say, oh, well why\Ndon't I just tweak part of the
Dialogue: 0,0:02:50.95,0:02:51.86,Default,,0000,0000,0000,,aluminum oxide?
Dialogue: 0,0:02:51.86,0:02:54.94,Default,,0000,0000,0000,,Why don't I put a 2/3 in\Nfront of this oxygen.
Dialogue: 0,0:02:54.94,0:02:56.64,Default,,0000,0000,0000,,You cannot do that.
Dialogue: 0,0:02:56.64,0:02:58.38,Default,,0000,0000,0000,,The equation is as it is.
Dialogue: 0,0:02:58.38,0:03:00.72,Default,,0000,0000,0000,,The molecule aluminum oxide\Nis aluminum oxide.
Dialogue: 0,0:03:00.72,0:03:04.63,Default,,0000,0000,0000,,You can't change the relative\Nratios of the aluminum and the
Dialogue: 0,0:03:04.63,0:03:07.31,Default,,0000,0000,0000,,oxygen within the aluminum\Noxide molecule.
Dialogue: 0,0:03:07.31,0:03:11.32,Default,,0000,0000,0000,,You can just change the number\Nof aluminum oxide molecules as
Dialogue: 0,0:03:11.32,0:03:13.46,Default,,0000,0000,0000,,a whole that you have,\Nin this case, two.
Dialogue: 0,0:03:13.46,0:03:14.00,Default,,0000,0000,0000,,So what did we do?
Dialogue: 0,0:03:14.00,0:03:14.80,Default,,0000,0000,0000,,We looked at the aluminum.
Dialogue: 0,0:03:14.80,0:03:17.06,Default,,0000,0000,0000,,We said, OK, we need two\Naluminums to have both sides
Dialogue: 0,0:03:17.06,0:03:18.66,Default,,0000,0000,0000,,of that be two.
Dialogue: 0,0:03:18.66,0:03:20.55,Default,,0000,0000,0000,,And then when we looked at\Noxygen, we said, well, if I
Dialogue: 0,0:03:20.55,0:03:23.31,Default,,0000,0000,0000,,multiply this by one and a half,\Nthen that becomes three
Dialogue: 0,0:03:23.31,0:03:26.34,Default,,0000,0000,0000,,oxygens here, because one and\Na half times two oxygens.
Dialogue: 0,0:03:26.34,0:03:27.88,Default,,0000,0000,0000,,And three oxygens there.
Dialogue: 0,0:03:27.88,0:03:30.40,Default,,0000,0000,0000,,And then all we said is, oh, I\Ncan't have a one half there,
Dialogue: 0,0:03:30.40,0:03:32.54,Default,,0000,0000,0000,,so let me multiply both\Nsides by two.
Dialogue: 0,0:03:32.54,0:03:37.36,Default,,0000,0000,0000,,And I ended up with four\Naluminums plus three oxygen
Dialogue: 0,0:03:37.36,0:03:41.98,Default,,0000,0000,0000,,molecules, or six oxygen atoms,\Nyields two molecules of
Dialogue: 0,0:03:41.98,0:03:43.66,Default,,0000,0000,0000,,aluminum oxide.
Dialogue: 0,0:03:43.66,0:03:46.07,Default,,0000,0000,0000,,Let's see if we can do\Nsome more of these.
Dialogue: 0,0:03:46.07,0:03:48.27,Default,,0000,0000,0000,,So here I have methane.
Dialogue: 0,0:03:48.27,0:03:50.20,Default,,0000,0000,0000,,And that g in parentheses,\NI just wanted to
Dialogue: 0,0:03:50.20,0:03:50.93,Default,,0000,0000,0000,,expose you to that.
Dialogue: 0,0:03:50.93,0:03:53.39,Default,,0000,0000,0000,,That just means it's a gas.
Dialogue: 0,0:03:53.39,0:03:58.34,Default,,0000,0000,0000,,So I have methane gas plus\Noxygen gas yields carbon
Dialogue: 0,0:03:58.34,0:04:00.09,Default,,0000,0000,0000,,dioxide gas plus water.
Dialogue: 0,0:04:00.09,0:04:02.41,Default,,0000,0000,0000,,That's an l there,\Nso liquid water.
Dialogue: 0,0:04:02.41,0:04:04.64,Default,,0000,0000,0000,,So what can we do here?
Dialogue: 0,0:04:04.64,0:04:07.44,Default,,0000,0000,0000,,So the general thing is, do\Nthe complicated molecules
Dialogue: 0,0:04:07.44,0:04:11.14,Default,,0000,0000,0000,,first, and then at the end you\Ncan worry about the single
Dialogue: 0,0:04:11.14,0:04:13.00,Default,,0000,0000,0000,,atom molecules.
Dialogue: 0,0:04:13.00,0:04:15.18,Default,,0000,0000,0000,,Because those are very\Neasy to play with.
Dialogue: 0,0:04:15.18,0:04:17.14,Default,,0000,0000,0000,,And the reason why you do that,\Nwhenever you change a
Dialogue: 0,0:04:17.14,0:04:19.68,Default,,0000,0000,0000,,number here-- let's say we're\Ntrying to engineer how many
Dialogue: 0,0:04:19.68,0:04:22.68,Default,,0000,0000,0000,,carbons we have on both sides of\Nthis equation-- if I set a
Dialogue: 0,0:04:22.68,0:04:24.68,Default,,0000,0000,0000,,number here, I'm also changing\Nthe number of hydrogens.
Dialogue: 0,0:04:24.68,0:04:26.14,Default,,0000,0000,0000,,Then I'll have to play with\Nthe hydrogens there.
Dialogue: 0,0:04:26.14,0:04:28.72,Default,,0000,0000,0000,,And at the end, I'll have\Nsome number of oxygens.
Dialogue: 0,0:04:28.72,0:04:30.63,Default,,0000,0000,0000,,And then I have to tweak this\Nnumber right there.
Dialogue: 0,0:04:30.63,0:04:33.77,Default,,0000,0000,0000,,So let's just start\Nwith the carbons.
Dialogue: 0,0:04:33.77,0:04:36.05,Default,,0000,0000,0000,,It seems complicated, but when\Nyou go step by step and you
Dialogue: 0,0:04:36.05,0:04:38.10,Default,,0000,0000,0000,,kind of play with things a\Nlittle bit, it should proceed
Dialogue: 0,0:04:38.10,0:04:39.55,Default,,0000,0000,0000,,fairly smoothly.
Dialogue: 0,0:04:39.55,0:04:41.07,Default,,0000,0000,0000,,So here I have two carbons.
Dialogue: 0,0:04:43.68,0:04:45.79,Default,,0000,0000,0000,,And here I have, on\Nthe right-hand
Dialogue: 0,0:04:45.79,0:04:47.81,Default,,0000,0000,0000,,side, only one carbon.
Dialogue: 0,0:04:47.81,0:04:49.79,Default,,0000,0000,0000,,So ideally I'd want two\Ncarbons on both
Dialogue: 0,0:04:49.79,0:04:50.78,Default,,0000,0000,0000,,sides of this equation.
Dialogue: 0,0:04:50.78,0:04:53.93,Default,,0000,0000,0000,,So let me put a two out here.
Dialogue: 0,0:04:53.93,0:04:55.70,Default,,0000,0000,0000,,So there you go, my\Ncarbons are happy.
Dialogue: 0,0:04:55.70,0:04:58.46,Default,,0000,0000,0000,,I now have two carbons\Nand two carbons.
Dialogue: 0,0:04:58.46,0:04:59.85,Default,,0000,0000,0000,,Now let me move to\Nthe hydrogens.
Dialogue: 0,0:04:59.85,0:05:02.01,Default,,0000,0000,0000,,Remember, I wanted to do the\Noxygens last, because I can
Dialogue: 0,0:05:02.01,0:05:05.00,Default,,0000,0000,0000,,just set this to whatever I want\Nit to be without messing
Dialogue: 0,0:05:05.00,0:05:08.07,Default,,0000,0000,0000,,up any of the other atoms. So on\Nthis side of the equation I
Dialogue: 0,0:05:08.07,0:05:11.37,Default,,0000,0000,0000,,have four hydrogen atoms. How\Nmany hydrogen atoms do I have
Dialogue: 0,0:05:11.37,0:05:12.69,Default,,0000,0000,0000,,on this side of the equation?
Dialogue: 0,0:05:12.69,0:05:16.32,Default,,0000,0000,0000,,So I have four hydrogen\Natoms here.
Dialogue: 0,0:05:16.32,0:05:18.15,Default,,0000,0000,0000,,How many do I have\Non this side?
Dialogue: 0,0:05:18.15,0:05:21.07,Default,,0000,0000,0000,,Well, I have two hydrogen\Natoms right there.
Dialogue: 0,0:05:21.07,0:05:24.10,Default,,0000,0000,0000,,So I want to have four on both\Nsides, so let me put a two in
Dialogue: 0,0:05:24.10,0:05:25.51,Default,,0000,0000,0000,,front of the water.
Dialogue: 0,0:05:25.51,0:05:29.31,Default,,0000,0000,0000,,So now I have four hydrogen\Natoms. Cool.
Dialogue: 0,0:05:29.31,0:05:30.85,Default,,0000,0000,0000,,Finally, oxygen.
Dialogue: 0,0:05:30.85,0:05:35.80,Default,,0000,0000,0000,,On the left-hand side I have two\Noxygen atoms. And on the
Dialogue: 0,0:05:35.80,0:05:37.78,Default,,0000,0000,0000,,right-hand side,\Nwhat do I have?
Dialogue: 0,0:05:37.78,0:05:41.97,Default,,0000,0000,0000,,I have two times this one\Noxygen, right here, so right
Dialogue: 0,0:05:41.97,0:05:44.29,Default,,0000,0000,0000,,now that's two, right?
Dialogue: 0,0:05:44.29,0:05:44.98,Default,,0000,0000,0000,,Two waters.
Dialogue: 0,0:05:44.98,0:05:49.45,Default,,0000,0000,0000,,And in each water I have one\Noxygen atom, but I have two
Dialogue: 0,0:05:49.45,0:05:52.17,Default,,0000,0000,0000,,water molecules, so I\Nhave two oxygens.
Dialogue: 0,0:05:52.17,0:05:56.27,Default,,0000,0000,0000,,And then in the carbon dioxide\NI have two oxygens in each
Dialogue: 0,0:05:56.27,0:05:56.84,Default,,0000,0000,0000,,carbon dioxide.
Dialogue: 0,0:05:56.84,0:05:58.95,Default,,0000,0000,0000,,And I have two carbon\Ndioxides, right?
Dialogue: 0,0:05:58.95,0:06:01.29,Default,,0000,0000,0000,,When I put that magenta\Ntwo out front.
Dialogue: 0,0:06:01.29,0:06:02.56,Default,,0000,0000,0000,,So how many oxygens do I have?
Dialogue: 0,0:06:02.56,0:06:03.42,Default,,0000,0000,0000,,Two times two.
Dialogue: 0,0:06:03.42,0:06:05.33,Default,,0000,0000,0000,,I have four oxygens.
Dialogue: 0,0:06:05.33,0:06:07.82,Default,,0000,0000,0000,,So on the left-hand side\NI have two oxygens.
Dialogue: 0,0:06:07.82,0:06:11.02,Default,,0000,0000,0000,,On the right-hand side I have\Nsix oxygens, two in the two
Dialogue: 0,0:06:11.02,0:06:13.43,Default,,0000,0000,0000,,molecules of water and\Nfour in the two
Dialogue: 0,0:06:13.43,0:06:15.77,Default,,0000,0000,0000,,molecules of carbon dioxide.
Dialogue: 0,0:06:15.77,0:06:18.46,Default,,0000,0000,0000,,So how do I make this\Ntwo into six?
Dialogue: 0,0:06:18.46,0:06:20.41,Default,,0000,0000,0000,,I want to have six oxygens\Non this side.
Dialogue: 0,0:06:20.41,0:06:21.69,Default,,0000,0000,0000,,I want to them to have\Nsix oxygens on the
Dialogue: 0,0:06:21.69,0:06:22.86,Default,,0000,0000,0000,,left-hand side as well.
Dialogue: 0,0:06:22.86,0:06:30.11,Default,,0000,0000,0000,,Well, if I put a three out here,\Nnow I have six oxygens.
Dialogue: 0,0:06:30.11,0:06:31.81,Default,,0000,0000,0000,,And our equation has\Nbeen balanced.
Dialogue: 0,0:06:31.81,0:06:35.21,Default,,0000,0000,0000,,I have two carbons on this\Nside, two carbons on that
Dialogue: 0,0:06:35.21,0:06:38.78,Default,,0000,0000,0000,,side, four hydrogens on this\Nside, four hydrogens on this
Dialogue: 0,0:06:38.78,0:06:42.04,Default,,0000,0000,0000,,side, six oxygens on this side,\Nand then-- four plus
Dialogue: 0,0:06:42.04,0:06:44.81,Default,,0000,0000,0000,,two-- six oxygens\Non that side.
Dialogue: 0,0:06:44.81,0:06:46.84,Default,,0000,0000,0000,,Next equation to balance.
Dialogue: 0,0:06:46.84,0:06:49.27,Default,,0000,0000,0000,,This actually becomes quite\Nfun once you get
Dialogue: 0,0:06:49.27,0:06:51.32,Default,,0000,0000,0000,,the knack of it.
Dialogue: 0,0:06:51.32,0:06:58.51,Default,,0000,0000,0000,,So I have ethane plus\Noxygen gas yielding
Dialogue: 0,0:06:58.51,0:07:00.58,Default,,0000,0000,0000,,carbon dioxide and water.
Dialogue: 0,0:07:00.58,0:07:03.23,Default,,0000,0000,0000,,So this is a combustion\Nprocess.
Dialogue: 0,0:07:03.23,0:07:05.28,Default,,0000,0000,0000,,Let's look at the\Ncarbons first. I
Dialogue: 0,0:07:05.28,0:07:06.81,Default,,0000,0000,0000,,have two carbons here.
Dialogue: 0,0:07:06.81,0:07:09.01,Default,,0000,0000,0000,,I have one carbon there.
Dialogue: 0,0:07:09.01,0:07:11.05,Default,,0000,0000,0000,,So let me put a two here.
Dialogue: 0,0:07:11.05,0:07:13.24,Default,,0000,0000,0000,,So now I have two carbons.
Dialogue: 0,0:07:13.24,0:07:14.09,Default,,0000,0000,0000,,Fair enough.
Dialogue: 0,0:07:14.09,0:07:15.90,Default,,0000,0000,0000,,Remember, I'm going to worry\Nabout the oxygen last. This
Dialogue: 0,0:07:15.90,0:07:16.91,Default,,0000,0000,0000,,one's actually not\Ntoo different
Dialogue: 0,0:07:16.91,0:07:18.42,Default,,0000,0000,0000,,than the last problem.
Dialogue: 0,0:07:18.42,0:07:21.13,Default,,0000,0000,0000,,I have six hydrogens here.
Dialogue: 0,0:07:21.13,0:07:23.40,Default,,0000,0000,0000,,I only have two hydrogens\Nin the water.
Dialogue: 0,0:07:23.40,0:07:28.09,Default,,0000,0000,0000,,So then we have three\Nwater molecules.
Dialogue: 0,0:07:28.09,0:07:30.47,Default,,0000,0000,0000,,And now I've balanced\Nout the hydrogens.
Dialogue: 0,0:07:30.47,0:07:33.52,Default,,0000,0000,0000,,I have six hydrogens on both\Nsides of the equation.
Dialogue: 0,0:07:33.52,0:07:36.06,Default,,0000,0000,0000,,And now let's deal\Nwith the water.
Dialogue: 0,0:07:36.06,0:07:40.33,Default,,0000,0000,0000,,Here on the right-hand side--\NI'll do it in this orange
Dialogue: 0,0:07:40.33,0:07:45.59,Default,,0000,0000,0000,,color-- I have two oxygens in\Neach carbon dioxide molecule.
Dialogue: 0,0:07:45.59,0:07:48.78,Default,,0000,0000,0000,,And I have two molecules,\Nso I have four oxygens.
Dialogue: 0,0:07:48.78,0:07:52.23,Default,,0000,0000,0000,,And I have one oxygen in\Neach water molecule.
Dialogue: 0,0:07:52.23,0:07:56.24,Default,,0000,0000,0000,,And I have three molecules, so\NI have three oxygens here.
Dialogue: 0,0:07:56.24,0:07:57.58,Default,,0000,0000,0000,,Is that right?
Dialogue: 0,0:07:57.58,0:08:00.19,Default,,0000,0000,0000,,Three oxygens on the\Nright-hand side.
Dialogue: 0,0:08:00.19,0:08:02.06,Default,,0000,0000,0000,,Yep, three water molecules.
Dialogue: 0,0:08:02.06,0:08:07.20,Default,,0000,0000,0000,,And then I have four oxygens\Nin the carbon dioxide.
Dialogue: 0,0:08:07.20,0:08:07.86,Default,,0000,0000,0000,,Right.
Dialogue: 0,0:08:07.86,0:08:09.79,Default,,0000,0000,0000,,So I have seven oxygens.
Dialogue: 0,0:08:09.79,0:08:11.59,Default,,0000,0000,0000,,I have seven oxygens on\Nthis side and I only
Dialogue: 0,0:08:11.59,0:08:13.13,Default,,0000,0000,0000,,have two on this side.
Dialogue: 0,0:08:13.13,0:08:15.58,Default,,0000,0000,0000,,So how can I make this\Ntwo into seven.
Dialogue: 0,0:08:15.58,0:08:19.36,Default,,0000,0000,0000,,Well I could multiply it\Nby three and a half.
Dialogue: 0,0:08:19.36,0:08:19.69,Default,,0000,0000,0000,,Right?
Dialogue: 0,0:08:19.69,0:08:21.62,Default,,0000,0000,0000,,Remember, I just want to have\Nseven on both sides.
Dialogue: 0,0:08:21.62,0:08:25.29,Default,,0000,0000,0000,,If I have three and a half\Nof these diatomic oxygen
Dialogue: 0,0:08:25.29,0:08:27.64,Default,,0000,0000,0000,,molecules-- three and a half\Ntimes two is seven-- so now I
Dialogue: 0,0:08:27.64,0:08:30.83,Default,,0000,0000,0000,,have seven oxygens on both\Nsides of the equation.
Dialogue: 0,0:08:30.83,0:08:32.87,Default,,0000,0000,0000,,Four plus three and\Nseven here.
Dialogue: 0,0:08:32.87,0:08:34.06,Default,,0000,0000,0000,,Two carbons.
Dialogue: 0,0:08:34.06,0:08:35.82,Default,,0000,0000,0000,,And then six hydrogens.
Dialogue: 0,0:08:35.82,0:08:38.43,Default,,0000,0000,0000,,And I'm almost done, except for\Nthe fact that you can't
Dialogue: 0,0:08:38.43,0:08:40.56,Default,,0000,0000,0000,,have fractions of molecules.
Dialogue: 0,0:08:40.56,0:08:42.41,Default,,0000,0000,0000,,So what you do is just multiply\Nboth sides of this
Dialogue: 0,0:08:42.41,0:08:45.76,Default,,0000,0000,0000,,equation by two or three, or\Nwhatever you need to multiply
Dialogue: 0,0:08:45.76,0:08:46.96,Default,,0000,0000,0000,,it to get rid of\Nthe fractions.
Dialogue: 0,0:08:46.96,0:08:50.80,Default,,0000,0000,0000,,So if I multiply everything\Nby two, I end up with two
Dialogue: 0,0:08:50.80,0:09:00.58,Default,,0000,0000,0000,,molecules of ethane plus seven\Nmolecules of diatomic oxygen,
Dialogue: 0,0:09:00.58,0:09:07.52,Default,,0000,0000,0000,,seven O2's, yielding two\Nmolecules of carbon dioxide--
Dialogue: 0,0:09:07.52,0:09:10.20,Default,,0000,0000,0000,,oh, sorry, I'm multiplying\Neverything by two, so four
Dialogue: 0,0:09:10.20,0:09:18.92,Default,,0000,0000,0000,,molecules of carbon dioxide,\Nplus six molecules of water.
Dialogue: 0,0:09:18.92,0:09:21.60,Default,,0000,0000,0000,,And just to make sure that all\Nstill works, if you want to,
Dialogue: 0,0:09:21.60,0:09:22.63,Default,,0000,0000,0000,,you can check.
Dialogue: 0,0:09:22.63,0:09:23.83,Default,,0000,0000,0000,,How much carbon do we have?
Dialogue: 0,0:09:23.83,0:09:25.98,Default,,0000,0000,0000,,I have four carbons here.
Dialogue: 0,0:09:25.98,0:09:28.18,Default,,0000,0000,0000,,I have four carbons here.
Dialogue: 0,0:09:28.18,0:09:29.52,Default,,0000,0000,0000,,How much hydrogen do I have?
Dialogue: 0,0:09:29.52,0:09:31.42,Default,,0000,0000,0000,,I have two times six.
Dialogue: 0,0:09:31.42,0:09:33.63,Default,,0000,0000,0000,,I have 12 hydrogens here.
Dialogue: 0,0:09:33.63,0:09:36.10,Default,,0000,0000,0000,,I have 12 hydrogens here.
Dialogue: 0,0:09:36.10,0:09:37.64,Default,,0000,0000,0000,,How much oxygen do I have?
Dialogue: 0,0:09:40.15,0:09:41.42,Default,,0000,0000,0000,,Let me do a different color.
Dialogue: 0,0:09:41.42,0:09:44.19,Default,,0000,0000,0000,,I have 14 oxygens here.
Dialogue: 0,0:09:44.19,0:09:48.04,Default,,0000,0000,0000,,And here I have eight oxygens.
Dialogue: 0,0:09:48.04,0:09:50.86,Default,,0000,0000,0000,,And here I have-- six times\None-- six oxygens.
Dialogue: 0,0:09:50.86,0:09:53.01,Default,,0000,0000,0000,,So six plus eight is 14.
Dialogue: 0,0:09:53.01,0:09:56.00,Default,,0000,0000,0000,,So my equation has\Nbeen balanced.
Dialogue: 0,0:09:56.00,0:09:58.23,Default,,0000,0000,0000,,So that one, a lot of people\Nmight find that to be a hard
Dialogue: 0,0:09:58.23,0:10:00.26,Default,,0000,0000,0000,,problem, because you have three\Nand a half, and just
Dialogue: 0,0:10:00.26,0:10:02.13,Default,,0000,0000,0000,,going straight to this might\Nseem non-intuitive.
Dialogue: 0,0:10:02.13,0:10:05.66,Default,,0000,0000,0000,,But if you just work from the\Nmore complicated molecules and
Dialogue: 0,0:10:05.66,0:10:07.98,Default,,0000,0000,0000,,you go atom by atom, and if you\Nend up with any fractions
Dialogue: 0,0:10:07.98,0:10:10.78,Default,,0000,0000,0000,,you just multiply both sides by\Nsome number to get rid of
Dialogue: 0,0:10:10.78,0:10:13.03,Default,,0000,0000,0000,,the fraction, of and\Nthen you're done.
Dialogue: 0,0:10:13.03,0:10:13.59,Default,,0000,0000,0000,,All right.
Dialogue: 0,0:10:13.59,0:10:15.85,Default,,0000,0000,0000,,Let's do another one.
Dialogue: 0,0:10:15.85,0:10:17.95,Default,,0000,0000,0000,,So this one looks all hairy.
Dialogue: 0,0:10:17.95,0:10:24.19,Default,,0000,0000,0000,,I have this iron oxide plus\Nsulfuric acid yields all this
Dialogue: 0,0:10:24.19,0:10:25.26,Default,,0000,0000,0000,,hairy stuff.
Dialogue: 0,0:10:25.26,0:10:30.00,Default,,0000,0000,0000,,But the key here to realize is\Nthat this group right here,
Dialogue: 0,0:10:30.00,0:10:35.17,Default,,0000,0000,0000,,this sulfate group,\Nstays together.
Dialogue: 0,0:10:35.17,0:10:35.48,Default,,0000,0000,0000,,Right?
Dialogue: 0,0:10:35.48,0:10:39.58,Default,,0000,0000,0000,,You have this SO4 there and\Nyou have this SO4 there.
Dialogue: 0,0:10:39.58,0:10:42.74,Default,,0000,0000,0000,,So to really simplify things for\Nour head, you can kind of
Dialogue: 0,0:10:42.74,0:10:44.01,Default,,0000,0000,0000,,treat that like an atom.
Dialogue: 0,0:10:44.01,0:10:45.41,Default,,0000,0000,0000,,So let's make a substitution.
Dialogue: 0,0:10:45.41,0:10:48.23,Default,,0000,0000,0000,,We'll substitute that for x.
Dialogue: 0,0:10:48.23,0:10:52.23,Default,,0000,0000,0000,,So if we rewrite this as--\NI'll do it in a vibrant
Dialogue: 0,0:10:52.23,0:11:03.39,Default,,0000,0000,0000,,color-- iron oxide plus H2--\Nthere's only one sulfate
Dialogue: 0,0:11:03.39,0:11:07.69,Default,,0000,0000,0000,,group here-- x.
Dialogue: 0,0:11:07.69,0:11:15.07,Default,,0000,0000,0000,,And then that yields\Ntwo irons, this
Dialogue: 0,0:11:15.07,0:11:15.94,Default,,0000,0000,0000,,molecule with two irons.
Dialogue: 0,0:11:15.94,0:11:18.07,Default,,0000,0000,0000,,And it has three of these\Nsulfate groups.
Dialogue: 0,0:11:21.14,0:11:22.39,Default,,0000,0000,0000,,And then plus water.
Dialogue: 0,0:11:26.45,0:11:28.87,Default,,0000,0000,0000,,All I did is replace the\Nsulfate with an x.
Dialogue: 0,0:11:28.87,0:11:32.04,Default,,0000,0000,0000,,And now we can treat that x like\Nan atom, and we can just
Dialogue: 0,0:11:32.04,0:11:33.83,Default,,0000,0000,0000,,balance the equation.
Dialogue: 0,0:11:33.83,0:11:36.04,Default,,0000,0000,0000,,Let's see, on the left-hand\Nside, how
Dialogue: 0,0:11:36.04,0:11:37.30,Default,,0000,0000,0000,,many irons do we have?
Dialogue: 0,0:11:37.30,0:11:39.00,Default,,0000,0000,0000,,We have two irons here.
Dialogue: 0,0:11:39.00,0:11:40.82,Default,,0000,0000,0000,,We have two irons there.
Dialogue: 0,0:11:40.82,0:11:45.19,Default,,0000,0000,0000,,So the irons look balanced,\Nat first glance.
Dialogue: 0,0:11:45.19,0:11:47.63,Default,,0000,0000,0000,,Let's deal with the oxygens.
Dialogue: 0,0:11:47.63,0:11:52.28,Default,,0000,0000,0000,,So if we have three oxygens\Nhere-- let me do it in a
Dialogue: 0,0:11:52.28,0:11:59.66,Default,,0000,0000,0000,,different color-- and we only\Nhave one oxygen here.
Dialogue: 0,0:11:59.66,0:12:03.48,Default,,0000,0000,0000,,Remember, there were some\Noxygens in this x group, but
Dialogue: 0,0:12:03.48,0:12:05.59,Default,,0000,0000,0000,,the sulfate group stayed\Ntogether, so we can just treat
Dialogue: 0,0:12:05.59,0:12:08.70,Default,,0000,0000,0000,,those separately.
Dialogue: 0,0:12:08.70,0:12:10.82,Default,,0000,0000,0000,,We want to have three oxygens\Non the right-hand side, as
Dialogue: 0,0:12:10.82,0:12:13.25,Default,,0000,0000,0000,,well, so let's stick\Na three here.
Dialogue: 0,0:12:13.25,0:12:14.50,Default,,0000,0000,0000,,Oops.
Dialogue: 0,0:12:19.71,0:12:21.04,Default,,0000,0000,0000,,So let me put that\Nthree there.
Dialogue: 0,0:12:21.04,0:12:23.96,Default,,0000,0000,0000,,So now we have three\Noxygens, as well.
Dialogue: 0,0:12:23.96,0:12:28.73,Default,,0000,0000,0000,,And then finally, let's\Nlook at the hydrogens.
Dialogue: 0,0:12:35.95,0:12:37.16,Default,,0000,0000,0000,,Let's see, how many hydrogens\Ndo we have here.
Dialogue: 0,0:12:37.16,0:12:41.27,Default,,0000,0000,0000,,We have six hydrogens now,\Non the right-hand side.
Dialogue: 0,0:12:41.27,0:12:42.84,Default,,0000,0000,0000,,Six hydrogens here.
Dialogue: 0,0:12:42.84,0:12:43.72,Default,,0000,0000,0000,,Three times two.
Dialogue: 0,0:12:43.72,0:12:46.77,Default,,0000,0000,0000,,And we want to have six\Nhydrogens here, so we have to
Dialogue: 0,0:12:46.77,0:12:48.91,Default,,0000,0000,0000,,have three of these molecules.
Dialogue: 0,0:12:48.91,0:12:52.20,Default,,0000,0000,0000,,And then finally, let's look at\Nthe sulfate group, that x.
Dialogue: 0,0:12:52.20,0:12:53.79,Default,,0000,0000,0000,,We have three x's here.
Dialogue: 0,0:12:57.09,0:13:01.35,Default,,0000,0000,0000,,And lucky for us, we have\Nthree x's over there.
Dialogue: 0,0:13:01.35,0:13:03.42,Default,,0000,0000,0000,,So our equation has\Nbeen balanced.
Dialogue: 0,0:13:03.42,0:13:05.76,Default,,0000,0000,0000,,And if we want to write it back\Nin terms of the sulfate
Dialogue: 0,0:13:05.76,0:13:09.49,Default,,0000,0000,0000,,terms, we can just un-substitute\Nthe x, and we're
Dialogue: 0,0:13:09.49,0:13:16.45,Default,,0000,0000,0000,,left with one molecule of iron\Noxide plus three molecules of
Dialogue: 0,0:13:16.45,0:13:21.54,Default,,0000,0000,0000,,sulfuric acid, H2SO4 -- I just\Nun-substituted the x with SO4
Dialogue: 0,0:13:21.54,0:13:28.57,Default,,0000,0000,0000,,-- yields one of these\Nmolecules, SO4 3.
Dialogue: 0,0:13:32.27,0:13:39.54,Default,,0000,0000,0000,,I just un-substituted the x plus\Nthree molecules of water.
Dialogue: 0,0:13:39.54,0:13:40.67,Default,,0000,0000,0000,,Let's do one more.
Dialogue: 0,0:13:40.67,0:13:43.80,Default,,0000,0000,0000,,And then I think we'll\Nbe all balanced out.
Dialogue: 0,0:13:43.80,0:13:47.75,Default,,0000,0000,0000,,Carbon dioxide plus hydrogen gas\Nyields methane plus water.
Dialogue: 0,0:13:47.75,0:13:51.70,Default,,0000,0000,0000,,So let's deal with the carbon\Nfirst. I have one carbon here,
Dialogue: 0,0:13:51.70,0:13:52.54,Default,,0000,0000,0000,,one carbon there.
Dialogue: 0,0:13:52.54,0:13:53.94,Default,,0000,0000,0000,,The carbons look happy.
Dialogue: 0,0:13:53.94,0:13:54.89,Default,,0000,0000,0000,,Let's look at the oxygen.
Dialogue: 0,0:13:54.89,0:13:56.92,Default,,0000,0000,0000,,I have two oxygens here.
Dialogue: 0,0:13:56.92,0:13:58.99,Default,,0000,0000,0000,,I have one oxygen there.
Dialogue: 0,0:13:58.99,0:14:02.35,Default,,0000,0000,0000,,So I want two oxygens here so\Nlet me stick a two there.
Dialogue: 0,0:14:02.35,0:14:04.30,Default,,0000,0000,0000,,And then let's deal with the\Nhydrogens last, because this
Dialogue: 0,0:14:04.30,0:14:06.65,Default,,0000,0000,0000,,is the easiest one to play with\Nbecause it doesn't affect
Dialogue: 0,0:14:06.65,0:14:11.03,Default,,0000,0000,0000,,any of the other atoms. So if\NI have two here and I have
Dialogue: 0,0:14:11.03,0:14:14.06,Default,,0000,0000,0000,,four, plus four here, right?
Dialogue: 0,0:14:14.06,0:14:15.86,Default,,0000,0000,0000,,I have four hydrogens there.
Dialogue: 0,0:14:15.86,0:14:18.16,Default,,0000,0000,0000,,And I have four hydrogens\Nthere.
Dialogue: 0,0:14:18.16,0:14:20.79,Default,,0000,0000,0000,,So I need eight hydrogens\Non the left-hand side.
Dialogue: 0,0:14:20.79,0:14:22.44,Default,,0000,0000,0000,,So I just put a four there.
Dialogue: 0,0:14:22.44,0:14:24.35,Default,,0000,0000,0000,,We're all done balancing.
Dialogue: 0,0:14:24.35,0:14:27.26,Default,,0000,0000,0000,,Anyway, hopefully you\Nfound that useful.