[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.00,0:00:00.00,Default,,0000,0000,0000,,
Dialogue: 0,0:00:00.00,0:00:04.09,Default,,0000,0000,0000,,Sal: We know that if we leave\Nwater to its own devices-- so
Dialogue: 0,0:00:04.09,0:00:08.00,Default,,0000,0000,0000,,you have some H2O-- that it's\Nan equilibrium with the
Dialogue: 0,0:00:08.00,0:00:10.02,Default,,0000,0000,0000,,autoionized version of itself.
Dialogue: 0,0:00:10.02,0:00:13.08,Default,,0000,0000,0000,,So a little bit of it will turn\Ninto some hydrogen ions,
Dialogue: 0,0:00:13.08,0:00:16.00,Default,,0000,0000,0000,,and we know that this really\Ntakes the form hydronium.
Dialogue: 0,0:00:16.00,0:00:18.04,Default,,0000,0000,0000,,That these attach themselves\Nto other water molecules.
Dialogue: 0,0:00:18.04,0:00:21.06,Default,,0000,0000,0000,,And it could be H3O, but\Nwe'll just write it
Dialogue: 0,0:00:21.06,0:00:23.06,Default,,0000,0000,0000,,as a hydrogen ion.
Dialogue: 0,0:00:23.06,0:00:26.02,Default,,0000,0000,0000,,Which is really just a\Nfree-floating proton.
Dialogue: 0,0:00:26.02,0:00:29.09,Default,,0000,0000,0000,,Plus hydroxide ion.
Dialogue: 0,0:00:29.09,0:00:34.05,Default,,0000,0000,0000,,And we also know that in kind of\Nan equilibrium state at 25
Dialogue: 0,0:00:34.05,0:00:36.08,Default,,0000,0000,0000,,degrees Celsius.
Dialogue: 0,0:00:36.08,0:00:39.04,Default,,0000,0000,0000,,And remember, equilibrium\Nconstants and equilibrium
Dialogue: 0,0:00:39.04,0:00:42.00,Default,,0000,0000,0000,,reactions are only dependent\Non the temperature.
Dialogue: 0,0:00:42.00,0:00:43.08,Default,,0000,0000,0000,,Nothing else.
Dialogue: 0,0:00:43.08,0:00:46.05,Default,,0000,0000,0000,,For a given molecule,\Nof course.
Dialogue: 0,0:00:46.05,0:00:48.09,Default,,0000,0000,0000,,So 25 degrees Celsius.
Dialogue: 0,0:00:48.09,0:00:51.06,Default,,0000,0000,0000,,And we also know, we did this\Ntwo videos ago, that the
Dialogue: 0,0:00:51.06,0:00:54.04,Default,,0000,0000,0000,,equilibrium constant-- as\Na review, that's the
Dialogue: 0,0:00:54.04,0:01:01.10,Default,,0000,0000,0000,,concentration of the products\Ndivided by the concentration
Dialogue: 0,0:01:01.10,0:01:03.02,Default,,0000,0000,0000,,of the reactants.
Dialogue: 0,0:01:03.02,0:01:05.03,Default,,0000,0000,0000,,But the reactant in this\Ncase is just water.
Dialogue: 0,0:01:05.03,0:01:06.06,Default,,0000,0000,0000,,It's the actual solvent.
Dialogue: 0,0:01:06.06,0:01:09.06,Default,,0000,0000,0000,,And if the reactant is what\Nyou're-- it's everywhere.
Dialogue: 0,0:01:09.06,0:01:11.08,Default,,0000,0000,0000,,So if you just go back to that\Nintuition example, the
Dialogue: 0,0:01:11.08,0:01:13.09,Default,,0000,0000,0000,,probability of finding\Nit is 1.
Dialogue: 0,0:01:13.09,0:01:17.03,Default,,0000,0000,0000,,So it's just always there,\Nso you don't included it.
Dialogue: 0,0:01:17.03,0:01:19.07,Default,,0000,0000,0000,,So you can just say divided by\N1 or whatever, and this is
Dialogue: 0,0:01:19.07,0:01:23.06,Default,,0000,0000,0000,,equal to the equilibrium\Nconstant of water.
Dialogue: 0,0:01:23.06,0:01:27.03,Default,,0000,0000,0000,,We learned that that's\N10 to the minus 14.
Dialogue: 0,0:01:27.03,0:01:32.05,Default,,0000,0000,0000,,Because water by itself will\Nhave a hydrogen concentration
Dialogue: 0,0:01:32.05,0:01:37.06,Default,,0000,0000,0000,,of 10 to the minus 7 and a\Nhydroxide concentration of 10
Dialogue: 0,0:01:37.06,0:01:38.09,Default,,0000,0000,0000,,to the minus 7.
Dialogue: 0,0:01:38.09,0:01:41.10,Default,,0000,0000,0000,,And if you take a log of\Neverything-- so if you take
Dialogue: 0,0:01:41.10,0:01:46.03,Default,,0000,0000,0000,,the pKw--
Dialogue: 0,0:01:46.03,0:01:47.02,Default,,0000,0000,0000,,What was that?
Dialogue: 0,0:01:47.02,0:01:49.02,Default,,0000,0000,0000,,If you put a p in front of\Nsomething, that means you're
Dialogue: 0,0:01:49.02,0:01:51.00,Default,,0000,0000,0000,,taking the negative log of it.
Dialogue: 0,0:01:51.00,0:01:54.05,Default,,0000,0000,0000,,So the negative log of 10 to the\Nminus 14-- the log base 10
Dialogue: 0,0:01:54.05,0:01:57.00,Default,,0000,0000,0000,,up to the minus 14\Nis minus 14.
Dialogue: 0,0:01:57.00,0:01:59.04,Default,,0000,0000,0000,,So the negative log\Nis just 14.
Dialogue: 0,0:01:59.04,0:02:07.08,Default,,0000,0000,0000,,So pKw is 14 and that is equal\Nto-- if I take the negative
Dialogue: 0,0:02:07.08,0:02:10.10,Default,,0000,0000,0000,,log of this side right here--\Nlet me do that.
Dialogue: 0,0:02:10.10,0:02:12.05,Default,,0000,0000,0000,,This is just a logarithm\Nproperty.
Dialogue: 0,0:02:12.05,0:02:15.09,Default,,0000,0000,0000,,This is more math\Nthan chemistry.
Dialogue: 0,0:02:15.09,0:02:23.06,Default,,0000,0000,0000,,So the log of H plus times OH\Ntimes our hydroxide ion.
Dialogue: 0,0:02:23.06,0:02:25.07,Default,,0000,0000,0000,,That's the same thing, just\Nthe logarithm properties.
Dialogue: 0,0:02:25.07,0:02:32.02,Default,,0000,0000,0000,,It's the same thing as minus\Nlog of H plus minus, or you
Dialogue: 0,0:02:32.02,0:02:40.02,Default,,0000,0000,0000,,could say plus the minus\Nlog of OH minus.
Dialogue: 0,0:02:40.02,0:02:41.07,Default,,0000,0000,0000,,And what is this?
Dialogue: 0,0:02:41.07,0:02:48.05,Default,,0000,0000,0000,,well this is just the\NpH, which is equal
Dialogue: 0,0:02:48.05,0:02:49.09,Default,,0000,0000,0000,,to the minus log.
Dialogue: 0,0:02:49.09,0:02:52.08,Default,,0000,0000,0000,,This is 10 to the\Nminus 7, right?
Dialogue: 0,0:02:52.08,0:02:54.02,Default,,0000,0000,0000,,10 to the minus 7.
Dialogue: 0,0:02:54.02,0:02:55.09,Default,,0000,0000,0000,,The log of that is minus 7.
Dialogue: 0,0:02:55.09,0:02:56.06,Default,,0000,0000,0000,,You have the minus in front.
Dialogue: 0,0:02:56.06,0:02:59.06,Default,,0000,0000,0000,,So its pH is equal to 7.
Dialogue: 0,0:02:59.06,0:03:01.04,Default,,0000,0000,0000,,And what is this?
Dialogue: 0,0:03:01.04,0:03:02.01,Default,,0000,0000,0000,,This over here.
Dialogue: 0,0:03:02.01,0:03:05.09,Default,,0000,0000,0000,,This is our pOH.
Dialogue: 0,0:03:05.09,0:03:08.07,Default,,0000,0000,0000,,The minus log of the hydroxide\Nconcentration.
Dialogue: 0,0:03:08.07,0:03:12.04,Default,,0000,0000,0000,,And of course, that was also\N10 to the minus 7.
Dialogue: 0,0:03:12.04,0:03:16.06,Default,,0000,0000,0000,,And so our pOH is equal to\Nlog of that is minus 7.
Dialogue: 0,0:03:16.06,0:03:17.06,Default,,0000,0000,0000,,You have a minus in front.
Dialogue: 0,0:03:17.06,0:03:19.00,Default,,0000,0000,0000,,It's equal to 7.
Dialogue: 0,0:03:19.00,0:03:24.00,Default,,0000,0000,0000,,So you get right there that\Nlittle formula that the pKw,
Dialogue: 0,0:03:24.00,0:03:28.05,Default,,0000,0000,0000,,or the negative log of the\Nequilibrium constant of water,
Dialogue: 0,0:03:28.05,0:03:41.02,Default,,0000,0000,0000,,pKw is equal to the pH of water\Nplus the pOH of water.
Dialogue: 0,0:03:41.02,0:03:43.08,Default,,0000,0000,0000,,And this, at 25 degrees Celsius,\Nthis is the thing
Dialogue: 0,0:03:43.08,0:03:45.06,Default,,0000,0000,0000,,that's going to stay constant\Nbecause we're going to start
Dialogue: 0,0:03:45.06,0:03:47.07,Default,,0000,0000,0000,,messing with these things\Nby throwing acid and
Dialogue: 0,0:03:47.07,0:03:49.01,Default,,0000,0000,0000,,base into the water.
Dialogue: 0,0:03:49.01,0:03:55.06,Default,,0000,0000,0000,,This thing is always going to\Nbe 14 at 25 degrees Celsius.
Dialogue: 0,0:03:55.06,0:03:57.08,Default,,0000,0000,0000,,Remember, as long as you keep\Ntemperature constant and
Dialogue: 0,0:03:57.08,0:04:01.02,Default,,0000,0000,0000,,you're not messing too much with\Nthe molecule itself, your
Dialogue: 0,0:04:01.02,0:04:03.02,Default,,0000,0000,0000,,equilibrium constant\Nstays constant.
Dialogue: 0,0:04:03.02,0:04:04.09,Default,,0000,0000,0000,,That's why it's called\Na constant.
Dialogue: 0,0:04:04.09,0:04:08.07,Default,,0000,0000,0000,,So with all of that out of the\Nway, let's think about what
Dialogue: 0,0:04:08.07,0:04:13.10,Default,,0000,0000,0000,,happens if I throw some acid\Ninto a-- let's say I have some
Dialogue: 0,0:04:13.10,0:04:15.02,Default,,0000,0000,0000,,hydrochloric acid.
Dialogue: 0,0:04:15.02,0:04:18.10,Default,,0000,0000,0000,,
Dialogue: 0,0:04:18.10,0:04:21.02,Default,,0000,0000,0000,,I'll use colors more\Ncreatively.
Dialogue: 0,0:04:21.02,0:04:23.03,Default,,0000,0000,0000,,So I have some hydrochloric\Nacid.
Dialogue: 0,0:04:23.03,0:04:26.07,Default,,0000,0000,0000,,It's in an aqueous solution.
Dialogue: 0,0:04:26.07,0:04:32.09,Default,,0000,0000,0000,,We know that it disassociates\Ncompletely, which means that
Dialogue: 0,0:04:32.09,0:04:39.04,Default,,0000,0000,0000,,we're just left with the\Nhydrogen ion, on which of
Dialogue: 0,0:04:39.04,0:04:42.07,Default,,0000,0000,0000,,course really attaches itself to\Nanother water molecule and
Dialogue: 0,0:04:42.07,0:04:44.08,Default,,0000,0000,0000,,becomes hydronium.
Dialogue: 0,0:04:44.08,0:04:51.06,Default,,0000,0000,0000,,Plus the chlorine anion,\Nor negative ion.
Dialogue: 0,0:04:51.06,0:04:53.08,Default,,0000,0000,0000,,Right there.
Dialogue: 0,0:04:53.08,0:05:09.01,Default,,0000,0000,0000,,And let's say that I do this\Nwith 1 molar-- or, you know,
Dialogue: 0,0:05:09.01,0:05:12.03,Default,,0000,0000,0000,,this is also sometimes written\Nas 1 capital M-- of
Dialogue: 0,0:05:12.03,0:05:13.08,Default,,0000,0000,0000,,hydrochloric acid.
Dialogue: 0,0:05:13.08,0:05:15.06,Default,,0000,0000,0000,,So essentially what\Nam I doing?
Dialogue: 0,0:05:15.06,0:05:18.06,Default,,0000,0000,0000,,I am taking 1 molar of\Nhydrochloric acid, literally
Dialogue: 0,0:05:18.06,0:05:26.10,Default,,0000,0000,0000,,means that I am taking 1\Nmole of HCl per liter
Dialogue: 0,0:05:26.10,0:05:28.00,Default,,0000,0000,0000,,of our whole solution.
Dialogue: 0,0:05:28.00,0:05:29.02,Default,,0000,0000,0000,,Which is mainly water.
Dialogue: 0,0:05:29.02,0:05:30.08,Default,,0000,0000,0000,,It's an aqueous solution.
Dialogue: 0,0:05:30.08,0:05:33.00,Default,,0000,0000,0000,,Per liter of water, right?
Dialogue: 0,0:05:33.00,0:05:36.08,Default,,0000,0000,0000,,So what's my concentration going\Nto be of these things
Dialogue: 0,0:05:36.08,0:05:37.04,Default,,0000,0000,0000,,right here?
Dialogue: 0,0:05:37.04,0:05:39.01,Default,,0000,0000,0000,,Or in particular, what's\Nthe concentration of
Dialogue: 0,0:05:39.01,0:05:41.05,Default,,0000,0000,0000,,the H going to be?
Dialogue: 0,0:05:41.05,0:05:46.02,Default,,0000,0000,0000,,Well, if this disassociated\Ncompletely, right?
Dialogue: 0,0:05:46.02,0:05:49.03,Default,,0000,0000,0000,,So all of this stuff-- this is\Nnot an equilibrium reaction.
Dialogue: 0,0:05:49.03,0:05:49.09,Default,,0000,0000,0000,,Remember.
Dialogue: 0,0:05:49.09,0:05:52.02,Default,,0000,0000,0000,,I only drew a one way\Narrow to the right.
Dialogue: 0,0:05:52.02,0:05:54.02,Default,,0000,0000,0000,,There's no even small\Nleftwards arrow.
Dialogue: 0,0:05:54.02,0:05:57.02,Default,,0000,0000,0000,,This is a strong hydrochloric\Nacid.
Dialogue: 0,0:05:57.02,0:06:01.05,Default,,0000,0000,0000,,So if you really put one molar\Nof this in an aqueous
Dialogue: 0,0:06:01.05,0:06:03.04,Default,,0000,0000,0000,,solution, you're not going\Nto see any of this.
Dialogue: 0,0:06:03.04,0:06:04.06,Default,,0000,0000,0000,,You're going to just see this.
Dialogue: 0,0:06:04.06,0:06:11.03,Default,,0000,0000,0000,,So you're going to have the\Nhydrogen concentration here in
Dialogue: 0,0:06:11.03,0:06:16.01,Default,,0000,0000,0000,,the aqueous solution is going\Nto be equal to 1 molar.
Dialogue: 0,0:06:16.01,0:06:19.08,Default,,0000,0000,0000,,And there's also going to be 1\Nmolar of chlorine anions, but
Dialogue: 0,0:06:19.08,0:06:22.05,Default,,0000,0000,0000,,we don't care about that.
Dialogue: 0,0:06:22.05,0:06:24.09,Default,,0000,0000,0000,,If I haven't said already, it\Nwould be nice to figure out
Dialogue: 0,0:06:24.09,0:06:27.03,Default,,0000,0000,0000,,what the pH of this\Nsolution is.
Dialogue: 0,0:06:27.03,0:06:29.08,Default,,0000,0000,0000,,Now that I've thrown\Nhydrochloric acid in it.
Dialogue: 0,0:06:29.08,0:06:32.00,Default,,0000,0000,0000,,Well the pH is just the hydrogen\Nconcentration.
Dialogue: 0,0:06:32.00,0:06:36.09,Default,,0000,0000,0000,,
Dialogue: 0,0:06:36.09,0:06:38.06,Default,,0000,0000,0000,,We already have the hydrogen\Nconcentration.
Dialogue: 0,0:06:38.06,0:06:42.02,Default,,0000,0000,0000,,That's 1 molar, or 1 mole\Nper liter of solution.
Dialogue: 0,0:06:42.02,0:06:53.04,Default,,0000,0000,0000,,So the pH is going to be equal\Nto the minus log base 10 of
Dialogue: 0,0:06:53.04,0:06:54.08,Default,,0000,0000,0000,,our hydrogen concentration.
Dialogue: 0,0:06:54.08,0:06:56.09,Default,,0000,0000,0000,,Of 1.
Dialogue: 0,0:06:56.09,0:06:59.01,Default,,0000,0000,0000,,10 to the what power\Nis equal to 1?
Dialogue: 0,0:06:59.01,0:07:01.10,Default,,0000,0000,0000,,Well, anything to the 0\Nof power is equal to
Dialogue: 0,0:07:01.10,0:07:02.09,Default,,0000,0000,0000,,1, including 10.
Dialogue: 0,0:07:02.09,0:07:05.10,Default,,0000,0000,0000,,So this is equal to 0\Nminus 0 is just 0.
Dialogue: 0,0:07:05.10,0:07:07.04,Default,,0000,0000,0000,,So your pH is 0.
Dialogue: 0,0:07:07.04,0:07:15.02,Default,,0000,0000,0000,,So if you have 1 molar of\Nhydrochloric acid, and you
Dialogue: 0,0:07:15.02,0:07:19.00,Default,,0000,0000,0000,,throw it into an aqueous\Nsolution.
Dialogue: 0,0:07:19.00,0:07:21.09,Default,,0000,0000,0000,,And, well, I guess I'm saying\Nyou're putting it into a
Dialogue: 0,0:07:21.09,0:07:23.04,Default,,0000,0000,0000,,solution when I tell\Nyou it's 1 molar.
Dialogue: 0,0:07:23.04,0:07:26.08,Default,,0000,0000,0000,,So if you have a concentration\Nof 1 mole per liter of
Dialogue: 0,0:07:26.08,0:07:31.02,Default,,0000,0000,0000,,solution, where the solvent\Nis water, you will end up
Dialogue: 0,0:07:31.02,0:07:33.09,Default,,0000,0000,0000,,with a pH of 0.
Dialogue: 0,0:07:33.09,0:07:35.02,Default,,0000,0000,0000,,The pH of 0.
Dialogue: 0,0:07:35.02,0:07:38.00,Default,,0000,0000,0000,,
Dialogue: 0,0:07:38.00,0:07:43.08,Default,,0000,0000,0000,,So pH of water without\Nany acid in it, that
Dialogue: 0,0:07:43.08,0:07:44.07,Default,,0000,0000,0000,,was equal to 7.
Dialogue: 0,0:07:44.07,0:07:49.04,Default,,0000,0000,0000,,And this is considered\Na neutral pH.
Dialogue: 0,0:07:49.04,0:07:54.00,Default,,0000,0000,0000,,Now we know that if you were\Nto have an aqueous solution
Dialogue: 0,0:07:54.00,0:07:59.00,Default,,0000,0000,0000,,with 1 molar of hydrochloric\Nacid, we can say-- I'll do it
Dialogue: 0,0:07:59.00,0:08:07.09,Default,,0000,0000,0000,,in red because-- pH of HCl\Nin water is equal to 0.
Dialogue: 0,0:08:07.09,0:08:11.04,Default,,0000,0000,0000,,So obviously a low pH\Nis more acidic.
Dialogue: 0,0:08:11.04,0:08:14.06,Default,,0000,0000,0000,,And we went over that\Nin previous videos.
Dialogue: 0,0:08:14.06,0:08:18.04,Default,,0000,0000,0000,,And let's figure out what the\NpOH of hydrochloric acid is.
Dialogue: 0,0:08:18.04,0:08:24.09,Default,,0000,0000,0000,,pOH of hydrochloric acid\Nin an aqueous solution.
Dialogue: 0,0:08:24.09,0:08:28.05,Default,,0000,0000,0000,,Well, this all goes back to Le\NChatelier's Principle, right?
Dialogue: 0,0:08:28.05,0:08:29.09,Default,,0000,0000,0000,,If you go back to what\Nwe said before.
Dialogue: 0,0:08:29.09,0:08:32.06,Default,,0000,0000,0000,,
Dialogue: 0,0:08:32.06,0:08:34.04,Default,,0000,0000,0000,,This is just pure water\Nright here.
Dialogue: 0,0:08:34.04,0:08:37.05,Default,,0000,0000,0000,,If we may have put 1 molar of\Nhydrochloric acid in here,
Dialogue: 0,0:08:37.05,0:08:46.01,Default,,0000,0000,0000,,we're essentially just throwing\Na ton of hydrogen
Dialogue: 0,0:08:46.01,0:08:46.10,Default,,0000,0000,0000,,protons in there.
Dialogue: 0,0:08:46.10,0:08:50.03,Default,,0000,0000,0000,,We're substantially increasing\Nthe concentration of this.
Dialogue: 0,0:08:50.03,0:08:52.09,Default,,0000,0000,0000,,And Le Chatelier's Principle\Nsays oh, well that means that
Dialogue: 0,0:08:52.09,0:08:55.06,Default,,0000,0000,0000,,a lot of this is going to be\Nconsumed and the reaction will
Dialogue: 0,0:08:55.06,0:08:56.09,Default,,0000,0000,0000,,go and this direction.
Dialogue: 0,0:08:56.09,0:08:59.02,Default,,0000,0000,0000,,The equilibrium reaction will\Ngo in that direction.
Dialogue: 0,0:08:59.02,0:09:00.01,Default,,0000,0000,0000,,But remember.
Dialogue: 0,0:09:00.01,0:09:03.04,Default,,0000,0000,0000,,Water by itself only had a 10 to\Nthe minus 7 concentration.
Dialogue: 0,0:09:03.04,0:09:10.09,Default,,0000,0000,0000,,We're throwing in a million--\NI mean it was one ten
Dialogue: 0,0:09:10.09,0:09:13.02,Default,,0000,0000,0000,,millionth of a mole per liter.
Dialogue: 0,0:09:13.02,0:09:17.01,Default,,0000,0000,0000,,Now we're throwing in--\Nwhat is that?
Dialogue: 0,0:09:17.01,0:09:17.08,Default,,0000,0000,0000,,10 to the 7th.
Dialogue: 0,0:09:17.08,0:09:22.04,Default,,0000,0000,0000,,We're throwing in 10 million\Ntimes as much hydrogen ions
Dialogue: 0,0:09:22.04,0:09:23.05,Default,,0000,0000,0000,,into that water.
Dialogue: 0,0:09:23.05,0:09:25.03,Default,,0000,0000,0000,,So all of this stuff\Njust gets consumed.
Dialogue: 0,0:09:25.03,0:09:26.04,Default,,0000,0000,0000,,Maybe it goes there.
Dialogue: 0,0:09:26.04,0:09:30.05,Default,,0000,0000,0000,,And so the concentration of this\Ngets thrown down really
Dialogue: 0,0:09:30.05,0:09:32.06,Default,,0000,0000,0000,,far because we're\Ndumping so much.
Dialogue: 0,0:09:32.06,0:09:34.10,Default,,0000,0000,0000,,And the concentration of this\Ngoes up because it can only
Dialogue: 0,0:09:34.10,0:09:37.00,Default,,0000,0000,0000,,consume so much of these guys.
Dialogue: 0,0:09:37.00,0:09:38.04,Default,,0000,0000,0000,,There's not that much of this.
Dialogue: 0,0:09:38.04,0:09:40.09,Default,,0000,0000,0000,,There's only 10 to the minus\N7th molar of this.
Dialogue: 0,0:09:40.09,0:09:43.02,Default,,0000,0000,0000,,So this ends up being 1 molar.
Dialogue: 0,0:09:43.02,0:09:46.01,Default,,0000,0000,0000,,And if this ends up being 1\Nmolar-- because 10 to the
Dialogue: 0,0:09:46.01,0:09:48.04,Default,,0000,0000,0000,,minus 7th molar, essentially,\Nyou can kind of view it as it
Dialogue: 0,0:09:48.04,0:09:50.06,Default,,0000,0000,0000,,all gets consumed with\Nthe stuff over here.
Dialogue: 0,0:09:50.06,0:09:53.07,Default,,0000,0000,0000,,What ends up being the\Nconcentration of the OH?
Dialogue: 0,0:09:53.07,0:09:58.08,Default,,0000,0000,0000,,Well, we already know that the\NpKw is 14 of water at 25
Dialogue: 0,0:09:58.08,0:10:03.03,Default,,0000,0000,0000,,degrees, and the pKw of water\Nis equal to the pH of your
Dialogue: 0,0:10:03.03,0:10:05.02,Default,,0000,0000,0000,,solution plus your pOH.
Dialogue: 0,0:10:05.02,0:10:12.03,Default,,0000,0000,0000,,So if your pH for hydrochloric\Nacid is 0, right?
Dialogue: 0,0:10:12.03,0:10:14.03,Default,,0000,0000,0000,,We have 1 molar of hydrochloric\Nacid.
Dialogue: 0,0:10:14.03,0:10:19.06,Default,,0000,0000,0000,,Then your pOH of 1 molar of\Nhydrochloric acid is 14.
Dialogue: 0,0:10:19.06,0:10:24.01,Default,,0000,0000,0000,,So right here, our pOH\Nis equal to 14.
Dialogue: 0,0:10:24.01,0:10:26.02,Default,,0000,0000,0000,,Now let's do the same thing\Nwith a base and figure out
Dialogue: 0,0:10:26.02,0:10:26.10,Default,,0000,0000,0000,,what its pH is.
Dialogue: 0,0:10:26.10,0:10:28.05,Default,,0000,0000,0000,,A strong base.
Dialogue: 0,0:10:28.05,0:10:30.06,Default,,0000,0000,0000,,And I think you'll see that\Nit's the opposite.
Dialogue: 0,0:10:30.06,0:10:35.07,Default,,0000,0000,0000,,So let's say I had potassium\Nhydroxide.
Dialogue: 0,0:10:35.07,0:10:37.05,Default,,0000,0000,0000,,It's a strong base.
Dialogue: 0,0:10:37.05,0:10:43.06,Default,,0000,0000,0000,,So it completely disassociates\Nin water to potassium cations.
Dialogue: 0,0:10:43.06,0:10:46.02,Default,,0000,0000,0000,,Positively charged ions.
Dialogue: 0,0:10:46.02,0:10:50.01,Default,,0000,0000,0000,,Plus hydroxide anions.
Dialogue: 0,0:10:50.01,0:10:51.04,Default,,0000,0000,0000,,It completed disassociates.
Dialogue: 0,0:10:51.04,0:10:53.06,Default,,0000,0000,0000,,So if I put anything in an\Naqueous solution-- I should
Dialogue: 0,0:10:53.06,0:10:54.09,Default,,0000,0000,0000,,write that down.
Dialogue: 0,0:10:54.09,0:10:59.02,Default,,0000,0000,0000,,
Dialogue: 0,0:10:59.02,0:11:02.05,Default,,0000,0000,0000,,Aqueous solution just means we\Nare in water, of course.
Dialogue: 0,0:11:02.05,0:11:05.09,Default,,0000,0000,0000,,And if we essentially put\N1 molar-- remember the
Dialogue: 0,0:11:05.09,0:11:07.01,Default,,0000,0000,0000,,concentration matters.
Dialogue: 0,0:11:07.01,0:11:07.10,Default,,0000,0000,0000,,You can't just say,\Noh, hydrochloric
Dialogue: 0,0:11:07.10,0:11:09.03,Default,,0000,0000,0000,,acid has a pH of 0.
Dialogue: 0,0:11:09.03,0:11:09.04,Default,,0000,0000,0000,,No.
Dialogue: 0,0:11:09.04,0:11:11.03,Default,,0000,0000,0000,,You have to say 1 molar\Nof hydrochloric
Dialogue: 0,0:11:11.03,0:11:13.07,Default,,0000,0000,0000,,acid has a pH of 0.
Dialogue: 0,0:11:13.07,0:11:15.00,Default,,0000,0000,0000,,And actually I didn't\Nwrite that.
Dialogue: 0,0:11:15.00,0:11:15.06,Default,,0000,0000,0000,,Let me write that.
Dialogue: 0,0:11:15.06,0:11:16.09,Default,,0000,0000,0000,,1 molar.
Dialogue: 0,0:11:16.09,0:11:19.03,Default,,0000,0000,0000,,
Dialogue: 0,0:11:19.03,0:11:22.04,Default,,0000,0000,0000,,And I'll leave you to figure out\Nwhat the pH or the pOH of
Dialogue: 0,0:11:22.04,0:11:24.03,Default,,0000,0000,0000,,2 molars of hydrochloric\Nacid is.
Dialogue: 0,0:11:24.03,0:11:26.10,Default,,0000,0000,0000,,Or a 10 molar of hydrochloric\Nacid.
Dialogue: 0,0:11:26.10,0:11:29.07,Default,,0000,0000,0000,,And figure out what\Nthose pH's are.
Dialogue: 0,0:11:29.07,0:11:36.01,Default,,0000,0000,0000,,But if we have 1 molar, of\Npotassium hydroxide.
Dialogue: 0,0:11:36.01,0:11:39.01,Default,,0000,0000,0000,,
Dialogue: 0,0:11:39.01,0:11:41.02,Default,,0000,0000,0000,,We have 1 molar of this.
Dialogue: 0,0:11:41.02,0:11:42.09,Default,,0000,0000,0000,,And it completely disassociates
Dialogue: 0,0:11:42.09,0:11:43.06,Default,,0000,0000,0000,,when it's in water.
Dialogue: 0,0:11:43.06,0:11:47.06,Default,,0000,0000,0000,,So you have none of\Nthis left over.
Dialogue: 0,0:11:47.06,0:11:50.05,Default,,0000,0000,0000,,What's your concentration\Nof OH?
Dialogue: 0,0:11:50.05,0:11:55.09,Default,,0000,0000,0000,,When your OH concentration\Nis going to be 1 molar.
Dialogue: 0,0:11:55.09,0:11:56.01,Default,,0000,0000,0000,,Right?
Dialogue: 0,0:11:56.01,0:11:58.03,Default,,0000,0000,0000,,If you had 1 mole per liter of\Nthis, you're going to 1 mole
Dialogue: 0,0:11:58.03,0:11:58.08,Default,,0000,0000,0000,,per liter of this.
Dialogue: 0,0:11:58.08,0:12:01.02,Default,,0000,0000,0000,,Because all of this just\Ndisappears in the water.
Dialogue: 0,0:12:01.02,0:12:02.04,Default,,0000,0000,0000,,So what is your pOH?
Dialogue: 0,0:12:02.04,0:12:05.04,Default,,0000,0000,0000,,
Dialogue: 0,0:12:05.04,0:12:08.02,Default,,0000,0000,0000,,POH is just the negative\Nlog of this.
Dialogue: 0,0:12:08.02,0:12:10.04,Default,,0000,0000,0000,,The log of 1 is 0.
Dialogue: 0,0:12:10.04,0:12:12.07,Default,,0000,0000,0000,,The negative of 0 is 0.
Dialogue: 0,0:12:12.07,0:12:19.01,Default,,0000,0000,0000,,And then your pH in this\Ncircumstance-- well, you could
Dialogue: 0,0:12:19.01,0:12:20.07,Default,,0000,0000,0000,,say, oh, it was the hydrogen\Nconcentration.
Dialogue: 0,0:12:20.07,0:12:22.05,Default,,0000,0000,0000,,You don't know what the hydrogen\Nconcentration is, but
Dialogue: 0,0:12:22.05,0:12:24.03,Default,,0000,0000,0000,,you know that when you throw\Na bunch of this stuff, it's
Dialogue: 0,0:12:24.03,0:12:26.02,Default,,0000,0000,0000,,going to sop up a bunch of\Nhydrogen and the hydrogen is
Dialogue: 0,0:12:26.02,0:12:27.01,Default,,0000,0000,0000,,going to go down a lot.
Dialogue: 0,0:12:27.01,0:12:28.05,Default,,0000,0000,0000,,But you're like, well,\Nhow do I measure it?
Dialogue: 0,0:12:28.05,0:12:29.06,Default,,0000,0000,0000,,Well, you remember it.
Dialogue: 0,0:12:29.06,0:12:32.03,Default,,0000,0000,0000,,25 degrees Celsius.
Dialogue: 0,0:12:32.03,0:12:34.09,Default,,0000,0000,0000,,The equilibrium constant\Nof water is equal to
Dialogue: 0,0:12:34.09,0:12:37.01,Default,,0000,0000,0000,,the pH plus the pOH.
Dialogue: 0,0:12:37.01,0:12:38.06,Default,,0000,0000,0000,,We showed that at the beginning\Nof the video.
Dialogue: 0,0:12:38.06,0:12:43.02,Default,,0000,0000,0000,,So 14 is equal to\Nyour pH plus 0.
Dialogue: 0,0:12:43.02,0:12:45.04,Default,,0000,0000,0000,,That's our pOH in this case.
Dialogue: 0,0:12:45.04,0:12:49.02,Default,,0000,0000,0000,,So our pH is 14.
Dialogue: 0,0:12:49.02,0:12:52.07,Default,,0000,0000,0000,,So if you have 1 molar-- I used\Npotassium hydroxide in
Dialogue: 0,0:12:52.07,0:12:55.08,Default,,0000,0000,0000,,this case-- but if you have 1\Nmolar of a strong base-- let
Dialogue: 0,0:12:55.08,0:12:57.03,Default,,0000,0000,0000,,me write that down.
Dialogue: 0,0:12:57.03,0:13:05.04,Default,,0000,0000,0000,,1 molar of strong base.
Dialogue: 0,0:13:05.04,0:13:08.02,Default,,0000,0000,0000,,Remember, strong is kind of an\Nofficial term in chemistry.
Dialogue: 0,0:13:08.02,0:13:11.01,Default,,0000,0000,0000,,It means complete\Ndisassociation.
Dialogue: 0,0:13:11.01,0:13:17.10,Default,,0000,0000,0000,,You have a pH of 14 and\Nyou have a pOH of 0.
Dialogue: 0,0:13:17.10,0:13:22.04,Default,,0000,0000,0000,,If you have 1 molar\Nof strong acid.
Dialogue: 0,0:13:22.04,0:13:25.07,Default,,0000,0000,0000,,If someone says that they have\Nsomething with a pH of 0 that
Dialogue: 0,0:13:25.07,0:13:31.05,Default,,0000,0000,0000,,they would like to maybe throw\Nat you, you should decline.
Dialogue: 0,0:13:31.05,0:13:34.06,Default,,0000,0000,0000,,Because it'll probably\Nhurt your
Dialogue: 0,0:13:34.06,0:13:37.02,Default,,0000,0000,0000,,chances of-- well, anyway.
Dialogue: 0,0:13:37.02,0:13:39.04,Default,,0000,0000,0000,,So let's say you have 1\Nmolar of strong acid.
Dialogue: 0,0:13:39.04,0:13:47.09,Default,,0000,0000,0000,,It's a pH of 0 and\Na pOH of 14.
Dialogue: 0,0:13:47.09,0:13:50.04,Default,,0000,0000,0000,,Anyway, maybe in the next video\NI'll actually show you--
Dialogue: 0,0:13:50.04,0:13:52.06,Default,,0000,0000,0000,,This might give you the\Nimpression that this is an
Dialogue: 0,0:13:52.06,0:13:53.08,Default,,0000,0000,0000,,absolute scale.
Dialogue: 0,0:13:53.08,0:13:57.05,Default,,0000,0000,0000,,That 0 is as acidic as you can\Nget, and 14 is as basic as you
Dialogue: 0,0:13:57.05,0:13:59.03,Default,,0000,0000,0000,,can get when you get the\NpH, but that's not
Dialogue: 0,0:13:59.03,0:14:00.00,Default,,0000,0000,0000,,that's not the case.
Dialogue: 0,0:14:00.00,0:14:01.06,Default,,0000,0000,0000,,You can actually get\Nabove this or you
Dialogue: 0,0:14:01.06,0:14:02.04,Default,,0000,0000,0000,,can get below this.
Dialogue: 0,0:14:02.04,0:14:07.02,Default,,0000,0000,0000,,This was this when you had one\N1 molar of a strong acid.
Dialogue: 0,0:14:07.02,0:14:10.02,Default,,0000,0000,0000,,If you had 2 molars of a strong\Nacid-- actually if you
Dialogue: 0,0:14:10.02,0:14:11.06,Default,,0000,0000,0000,,had 10 molars.
Dialogue: 0,0:14:11.06,0:14:11.08,Default,,0000,0000,0000,,Right?
Dialogue: 0,0:14:11.08,0:14:12.08,Default,,0000,0000,0000,,Let's say you get your hydrogen
Dialogue: 0,0:14:12.08,0:14:19.09,Default,,0000,0000,0000,,concentration to 10 molar.
Dialogue: 0,0:14:19.09,0:14:23.01,Default,,0000,0000,0000,,So if you had 10 molar of a\Nstrong acid, you apply that in
Dialogue: 0,0:14:23.01,0:14:24.01,Default,,0000,0000,0000,,an aqueous solution.
Dialogue: 0,0:14:24.01,0:14:27.01,Default,,0000,0000,0000,,It is, when I say it's a\Nmolar by definition.
Dialogue: 0,0:14:27.01,0:14:28.08,Default,,0000,0000,0000,,What's your pH going to be?
Dialogue: 0,0:14:28.08,0:14:33.00,Default,,0000,0000,0000,,Your pH is going to be the\Nminus log base 10 of 10.
Dialogue: 0,0:14:33.00,0:14:34.04,Default,,0000,0000,0000,,The log, base 10 of 10, is 1.
Dialogue: 0,0:14:34.04,0:14:36.03,Default,,0000,0000,0000,,10 to the first power is one.
Dialogue: 0,0:14:36.03,0:14:37.08,Default,,0000,0000,0000,,So this is equal to minus 1.
Dialogue: 0,0:14:37.08,0:14:40.08,Default,,0000,0000,0000,,So minus 1 pH would-- if\Nyou had 10 molar of say
Dialogue: 0,0:14:40.08,0:14:45.01,Default,,0000,0000,0000,,hydrochloric acid or nitric acid\Nor anything like that.
Dialogue: 0,0:14:45.01,0:14:47.00,Default,,0000,0000,0000,,Anyway, that's all\Nfor this video.
Dialogue: 0,0:14:47.00,0:14:49.01,Default,,0000,0000,0000,,I'll see you in the next one.