0:00:00.000,0:00:01.400


0:00:01.400,0:00:10.833
Alright, we’re going to start this first Camtasia [br]of Chapter 15, by talking about definitions of [br]acids and bases. Acids and bases are

0:00:10.833,0:00:14.799
things that have been known about for [br]hundreds, if not thousands, of years. Um,

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there were lots of different compounds that [br]people discovered over time that

0:00:19.833,0:00:24.899
they, ah, put in these different classifications. [br]And originally acids

0:00:24.900,0:00:32.433
and bases were just defined based on some [br]of the basic properties that they had. For [br]instance,

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acids were things that would taste sour, OK? [br]Um, they didn’t know what it was that made it [br]taste sour, but they knew that it tasted sour.

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Um, they would react with certain metals, not [br]all metals, but would react with SOME metals [br]to make hydrogen gas,

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which you have seen before. Alright. Um,

0:00:58.700,0:01:06.600
one of the things about, ah, acids, or bases, is [br]that they would react with certain compounds [br]and change their color. And one of the

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first things that was really used as a test was [br]litmus, it’s from a fungus, um,

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but what it would do, an acid would turn litmus [br]to a red color. OK, so

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these were different things that they noticed [br]that all these compounds had in common. [br]Um, bases

0:01:24.300,0:01:33.466
would be things that would taste bitter, OK, [br]they didn’t have a particular reaction with [br]metals that they did, um, but they would

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feel slippery or soapy, turns out that’s a [br]reaction with your skin, um, but it would, feel [br]slippery or soapy, um, when you touched it.

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And they also would change the color of [br]litmus, they would turn litmus, um, into a blue [br]color. OK, so over the years,

0:01:51.600,0:01:59.566
there were MANY, MANY, different compounds, [br]that when they were discovered or tested, um, [br]it would taste sour. OK, and so when they,

0:01:59.566,0:02:02.166
well, they would add it to some of the metal, [br]and …HUH, it might make a

0:02:02.166,0:02:04.799
little bit of hydrogen gas. But it would definitely [br]change the color of the litmus.

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If there’s something that they would, you know, [br]feel that it was kind of soapy or slippery they’d [br]taste it and it tastes bitter, they’d test against

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litmus and it turned litmus blue, and so lots [br]and lots of different compounds that they were [br]able to separate in to

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acids or bases based on these properties, but [br]over the years as they started to

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look at, you know, what was in these different [br]compounds, there didn’t

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seem to be anything really…that stood out. [br]That made something acidic or basic. Um, the [br]one other

0:02:33.233,0:02:43.733
thing about the acids and bases is that if you [br]combine them, um, they would combine to [br]make salt water. Uh,

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so they would make a salt, and water if it was [br]an aqueous solution, um,

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and when you had the salt you really didn’t [br]have your acidic or basic properties anymore; [br]it was no longer

0:02:54.300,0:03:00.100
sour, it was no longer bitter, it didn’t really feel [br]soapy any more, it didn’t react with metals. [br]Um, and so

0:03:00.100,0:03:11.233
essentially, this was neutralization. OK? They [br]essentially cancelled each other out and we [br]got this salt water, OK? So, they were known [br]about

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for … MANY, MANY years, but they didn’t really [br]know WHY they behaved that way, and there [br]were lots and lots of different reasons

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that were thrown out, um, some stuck around [br]more than others. OK?

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One of the first ones that really made...sense, [br]in hind sight, um, was proposed

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by a guy by the name of Arrhenius, um, this is [br]the same guy who had the Arrhenius Equation [br]that you learned for the

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kinetics chapter. Um, and Arrhenius, what he [br]was doing was he was working on his PhD [br]thesis in the 1880’s.

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And, (sigh) he was looking at acids and bases, [br]and one of the things that … again, he was [br]trying to

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figure out what was going on. Um, and so to [br]figure out what was going on, um, he actually [br]was looking at…

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conductivity of solutions. OK? Annnd, it’s [br]been a while since we’ve done conductivity, so [br]we are going to

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look at a couple of videos real quick to remind [br]ourselves of conductivity of solutions. Alriight.

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So...[br]"Well, we’ve gotta demonstrate that, I think is [br]the best thing to do. So, what I have here,

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is ah, just some water, I’ll put that there, and [br]more water. Then I have this awesome [br]testing machine, which is, ah, lethal in the [br]wrong hands,

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I’ll plug this in here, and there is a light bulb on [br]the bottom as you can see, which will be

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on the top in a minute, and there’s a couple of [br]electrodes sticking out the top. But if [br]something connects the electrodes the light [br]bulb

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lights, OK? So obviously a piece of metal [br]conducts electricity very well, the electrons fly [br]through it and the

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light bulb lights up. Now, how about water? Is [br]that an electrical conductor? Oh, …

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some people,….no, it’s not distilled (inaudible) [br]with that, aaaaah, some people say yes, some [br]people

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say no. Whadya think? Welll, not enough to [br]light up the light bulb.

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But if I was having a bath in there, and [br]somebody threw this in I’d be dead.OK? [br]There is enough

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electrical current passing through there to zap [br]a person but not enough to light up a 20-watt [br]light bulb or whatever this is, so, not a whole [br]lotta

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current travels through. In a light bulb like this, [br]you might have an ampere of current, to light it [br]up nice and bright. In the bath tub it

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only takes milliamps to go through your body [br]to kill you. OK, so, distilled water or

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just plain tap water, not much conductivity. [br]Now, what is it that carries charge?

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In the case of, of, this thing it’s electrons being [br]transferred through the

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spatula, and the electrons are mobile in the [br]metal so they are what carry charge.

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But what if we have something in solution-like [br]some sodium chloride, common table salt, [br]safety sealed.

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So let’s put some salt in here. Stir it up a little [br]bit, now this is dissolving, and my claim is that [br]this is turning into ions, but, ah, the only way [br]we could

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know that there are ions in there would be to [br]show that the solution has some electrical [br]conductivity. And you can see that, of course [br]it,

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does. So, what’s happening here? It’s the ions [br]now in the solution that are carrying the [br]charge. Positive and negative charges; [br]positive

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sodium ions, negative chloride ions, those are [br]the things that are carrying the charge from [br]one electrode to the other and completing the

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circuit. In ordinary water there are not [br]sufficient number of ions – there are some [br]ions but not a sufficient number to, ah, to

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see that, ah, enough current would be, um, [br]carried to light up this thing. Light up this bulb. [br]Now, does it mean that when we dissolve

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something it necessarily conducts electricity? [br]Well, here’s some sugar. So I’ll throw some [br]sugar in,

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stir that around. You know that sugar is fairly [br]soluble in water. I put about the same amount [br]of sugar in there

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that I had, ah, sodium chloride in the other [br]one. So let’s see what happens. Zippo! So [br]just

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because something dissolves in water does [br]not mean that it has separated into ions. The [br]sodium chloride does,

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the sugar doesn’t but yet it’s still soluble so [br]there’s two different things going on in there. [br]This part of the way

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tells how you can really kill someone, you [br]throw sodium chloride in the water first and [br]then throw the toaster in bath tub.

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One of my favorite shows is called, [br]“Mythbusters,” I just, I laugh my head off when [br]they do

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things, and they, they demonstrated this, and [br]they threw sodium chloride in

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and threw their dummy in and yes, he got [br]electrocuted more than if there was no sodium [br]chloride in. Somebody have a question?

0:07:48.566,0:07:59.666
(student in background) Well, your body has [br]salt on it, that’s true just not enough. If you put [br]more in you get more conductivity and …

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the guy’s even deader.”[br]Alright. So that pretty much just demonstrates [br]the idea of conductivity.

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And as he said when we have ions present in [br]solution, then, um, the

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light bulb lights up. When there weren’t ions [br]present in solution, like with the, um,

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the, ah, sugar, then there was no conductivity. [br]Now, he just

0:08:21.566,0:08:30.932
did salt and sugar, we’re gonna look at a [br]couple of other solutions, I think, if it goes, [br]there we go. There we go. Um, so

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this has a variety of different things. Same [br]type of idea, he has a probe

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(TAP WATER), little bit of lighting up, you can [br]actually see that one, you couldn’t see it on the [br]other one.

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(DISTILLED WATER, huh, what? SALT [br]WATER, one teaspoon per cup.) Nice and [br]bright.

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(HYDROCHLORIC ACID), HCl here, nice and [br]bright.

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(SODIUM HYDROXIDE, just as concentrated) [br]Nice and bright. (SUGAR WATER), here’s our [br]sugar again.

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(SWEET), Vinegar (VINEGAR, a weak acid), [br]lights up, not quite as much as the HCl did [br]before. (ETHANOL, a dissociative

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that doesn’t associate – don’t try this at home, [br]BARIUM SULFATE, it’s insoluble. Nooo [br]conductivity here!) Alright,

0:09:44.633,0:09:56.999
dorky looking guy. Alright, um, so, the point [br]there, though was that um, some solutions [br]conduct, some don’t. And, what was

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known about a lot of the acids at the time was [br]that they had formulas of molecular [br]compounds.

0:10:01.833,0:10:06.666
So we have things like, ah, HCl, where it’s [br]known that hydrogen bonds

0:10:06.666,0:10:17.332
to chlorine. Um, and that we have things like [br]acidic acid – CH3COOH, ok? So, a lot of the

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acids were known to be, um, molecular [br]compounds. OK?

0:10:23.666,0:10:29.466
And it was assumed that if you have molecular [br]compounds, something like sugar, um, that [br]when you put it in,

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water, it is not going to split up into ions, [br]‘cause it is a molecule. If you have salt, [br]something

0:10:35.266,0:10:44.532
like Sodium Chloride, and you put it into sugar, [br]OK? Um, you’re going to get your individual [br]ions. OK? Because it

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is ionic. Now, this was the excepted [br]reasoning. What Arrhenius said, though, was [br]he said, “You know what? When I put acids in [br]water, whether

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it’s a strong acid or a weak acid, I get things [br]lighting up.” And so, what he said was that [br]even though acids are molecular compounds,

0:11:00.166,0:11:12.466
they can ionize. OK? Um, helps if I spell it [br]right. They can ionize. They can create ions [br]in solution. And so what that

0:11:12.466,0:11:17.632
means is that something has to come off, and [br]what he figured out was,

0:11:17.633,0:11:22.799
well, all of them have some hydrogen floating [br]around that is able to fall off.

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And so Arrhenius said that acids are things [br]which increase the concentration of H plus in [br]solution, bases are

0:11:34.133,0:11:42.766
things which increase the concentration of [br]hydroxides in solution. OK? Now, this was a [br]very bold statement

0:11:42.766,0:11:52.832
back in the 1880’s, when he made it. Um, his [br]PhD committee, um, that you present your [br]research to, that say “yay or nay,”

0:11:52.833,0:11:57.733
um, did not agree with it, he almost failed. If he [br]had we probably

0:11:57.733,0:12:02.633
wouldn’t have had our Arrhenius Equation. [br](laughs so inaudible word) named after him.

0:12:02.633,0:12:10.966
It was only through some political [br]maneuvering that he was able to pass, um, [br]and it turns out he was right. OK, acids are [br]things that

0:12:10.966,0:12:17.666
increase the concentration of H plus, bases [br]are things that increase the concentration of [br]hydroxide, um, but this was a very radical

0:12:17.666,0:12:23.566
idea at the time, Ok? Now one of the things we [br]talk about acids and bases, um, lot of times [br]we are dealing with water.

0:12:23.566,0:12:33.666
So, when we have an H plus in water, OK, we [br]have a bare proton, floating around in water, [br]and water has all

0:12:33.666,0:12:40.632
those lone pair electrons on the oxygen, OK? [br]And so what is going to happen is that, in [br]water, they are

0:12:40.633,0:12:46.933
going to make, um, a coordinate covalent [br]bond, and they are going to make

0:12:46.933,0:12:53.266
H3O plus, which is our hydronium ion, OK? [br]So technically, when we are dealing

0:12:53.266,0:12:59.366
with acids in aqueous solution-which is where [br]we see them most of the time-um, what we [br]get is not

0:12:59.366,0:13:06.132
an increase in the concentration of H plus, [br]what we get is an increase in the [br]concentration of hydronium ion. OK? Um,

0:13:06.133,0:13:15.999
but, ah, just some terminology to be aware of, [br]OK, because sometimes we’ll write our acids [br]as H plus, sometimes we’ll write them as

0:13:16.000,0:13:25.433
H3O plus. Sometimes we will call them a [br]proton, because H plus is just a bare proton [br]floating around, or a hydrogen

0:13:25.433,0:13:29.666
ion, not as often but we could, sometimes [br]we’ll call it hydronium.

0:13:29.666,0:13:33.932
So the terms are used interchangeably, [br]sometimes you’ll see H plus people call [br]hydronium,

0:13:33.933,0:13:43.133
sometimes you’ll see H3O plus people call it [br]protons, they use the terms and, um, symbols [br]interchangeably. OK. But that is

0:13:43.133,0:13:51.866
our acid; we increase the H plus in solution, [br]our base increase is hydroxide, according to [br]Arrhenius. OK? This is a

0:13:51.866,0:13:55.699
really, really great definition of acid-base. It’s [br]what we usually

0:13:55.700,0:13:59.566
use to start out when we’re teaching it, um, [br]but there are a couple of problems.

0:13:59.566,0:14:14.232
OK? First of all, you have to be in water. If [br]you’re not in water, it doesn’t really work very [br]well. OK. The second one is you have to

0:14:14.233,0:14:22.799
have both H plus and hydroxide, when you’re [br]not in water you’ve often don’t have hydroxide, [br]OK?

0:14:22.800,0:14:38.066
Um, and so there are some things that we … [br]um, describe as acids and bases which um,[br]…may or may not work, OK, using Arrhenius’s

0:14:38.066,0:14:45.699
definition. So to illustrate that, quickie little [br]video here, um, what we have is a flask that

0:14:45.700,0:14:53.333
has ammonium, and then, ah, a Q-tip that has [br]some HCl, OK? Now,

0:14:53.333,0:15:05.399
HCl we know is an acid, ammonia we know is [br]a base, OK? Um, we kind of put the two right [br]by each other and we are getting ammonium

0:15:05.400,0:15:17.533
chloride, which is a salt, so we’re even doing a [br]neutralization. Um, but if we think about the [br]reaction between, um,

0:15:17.533,0:15:36.233
HCl gas and NH3 gas, what we wind up [br]getting is NH4Cl solid.

0:15:36.233,0:15:40.599
No H plus floating around in solution to [br]increase its concentration, definitely no

0:15:40.600,0:15:45.000
hydroxide floating around in solution to [br]increase its concentration. So even though we [br]have something

0:15:45.000,0:15:54.200
that we know is an acid and something that [br]we know is a base, and they’re coming [br]together to make salt, a neutralization like we [br]said acids and

0:15:54.200,0:16:02.033
bases do, um, according to the Arrhenius [br]definition, um, we can’t classify this as an [br]acid-base reaction. OK? So there had to be

0:16:02.033,0:16:14.899
other ways of describing it. Um, the next best [br]way of describing it was proposed in 1923 by [br]a pair of guys, one named

0:16:14.900,0:16:21.133
Bronsted, the other named Lowry; um, they [br]were not working together, they published their [br]definitions

0:16:21.133,0:16:27.766
within a couple months of each other, and so [br]this has just become the Bronsted-Lowry [br]definition. And so what these two guys did,

0:16:27.766,0:16:36.899
was they said, “Well, you know what? We [br]don’t want to use both H plus AND hydroxide, [br]um, so we’re just going to focus

0:16:36.900,0:16:45.700
on the H plus.” OK? And so what they did was [br]they looked at the reaction, if I have an acid [br]and a base, OK, they come together

0:16:45.700,0:16:53.966
and make water. And so, they said, “OK, [br]we’re gonna say that our H pluses are acid, [br]what is the base doing

0:16:53.966,0:17:01.832
in relation to the H plus?” And they figured out [br]that what it’s doing is it is picking up an H plus, [br]OK? And so they said

0:17:01.833,0:17:16.866
that an acid is something that donates a [br]proton and base is therefore something that [br]accepts the proton. OK. Um,

0:17:16.866,0:17:23.199
all of the previous definitions of acid and base [br]that Arrhenius gave still worked.

0:17:23.200,0:17:29.533
OK, so if you think about it, ah, if we have HCl, [br]OK, and we put it in water,

0:17:29.533,0:17:40.366
OK, HCl we said is an acid. OK? It’s going to [br]make hydronium ion and chloride ion, OK? [br]And so HCl still

0:17:40.366,0:17:48.399
functions as an acid. It is donating a proton, [br]what it’s donating it to here in this case is [br]water, and so water is going to function as a [br]base.

0:17:48.400,0:18:00.366
Um, something like ammonia, OK? Um, when [br]we put it in water, we get ammonium ion and [br]hydroxide, OK?

0:18:00.366,0:18:05.932
It’s the hydroxide here that, um, allowed [br]Arrhenius to call it a

0:18:05.933,0:18:11.499
base-ammonia base. Um, in this case though, [br]for the Bronsted-Lowry, what is

0:18:11.500,0:18:21.333
happening is it is picking up a proton from the [br]water. OK? That’s what gives us our NH4 plus [br]and what we have left over is

0:18:21.333,0:18:26.066
the hydroxide, OK, so things that were acids [br]according to the Arrhenius

0:18:26.066,0:18:30.799
definition are still acids, things that were bases [br]according to the Arrhenius definition,

0:18:30.800,0:18:39.233
um, are still bases, the one thing that is [br]different now though, is that I can do [br]something like my gas phase reaction, OK? I [br]can have

0:18:39.233,0:18:55.899
HCl and NH3, OK? And they can still function [br]as an acid and a base. So the HCl donates, so [br]it is an acid, um, the NH3 accepts, so it is a

0:18:55.900,0:19:03.366
base, OK? And I make my NH4 plus ion and [br]my chloride ion, which come together

0:19:03.366,0:19:10.866
to make the ammonium chloride salt. OK? So. [br]It was a much more, ah,

0:19:10.866,0:19:18.666
generic definition. Um, it applied to things that [br]didn’t have hydroxides floating around in [br]solution, and it also

0:19:18.666,0:19:23.132
got rid of, um, the need for water. So we have [br]gas phase

0:19:23.133,0:19:27.599
things now, this definition works really, really [br]good in organic solvents where we don’t have [br]any

0:19:27.600,0:19:35.566
water present. And so, it’s a much more [br]generic definition of acid-base than the [br]Arrhenius was. OK? We have

0:19:35.566,0:19:46.666
couple of results from this, though. Um, one of [br]the things is we have some species that can [br]act as an acid or base. Here with the water,

0:19:46.666,0:19:49.832
um, when the water was combined with the [br]HCl it functioned as a base. When the

0:19:49.833,0:19:52.999
water was combined with the ammonia it [br]functioned as an acid. OK?

0:19:53.000,0:20:05.233
That is what is known as an amphoteric [br]species. OK? It is something that

0:20:05.233,0:20:16.799
can act as an acid or a base, depending on [br]what is put in it. OK?

0:20:16.800,0:20:30.333
So the best example of that is our water, OK? [br]Other things are polyprotic acids, that have [br]lost

0:20:30.333,0:20:48.466
at least one but not all, of their protons, OK? [br]So for example, if I have

0:20:48.466,0:20:57.666
bicarbonate, HCO3 minus, OK? It lost one, but [br]it hasn’t lost both, OK? So what it can do

0:20:57.666,0:21:09.799
is it can pick up that proton, so it can accept a [br]proton to make H2CO3. If it accepts a proton [br]um, then it is acting

0:21:09.800,0:21:25.433
as a base. OK? But it also has this H plus [br]here, that it can get rid of – so it can donate a [br]proton and act as an acid to make CO3 with a [br]negative

0:21:25.433,0:21:31.933
2 charge. OK. So. Amphoteric species. Water [br]is one of the great examples, but also these [br]polyprotic acids that

0:21:31.933,0:21:38.866
have lost AT LEAST ONE, so it can get it back [br]and act as a base, BUT NOT ALL, so it can [br]lose more and act as an acid

0:21:38.866,0:21:52.599
um, of the protons. OK? That is one result. [br]Another result of, um, our, ah, Bronsted-Lowry [br]definition, is that

0:21:52.600,0:22:07.066
we have are called conjugate acid-base pairs. [br]OK? Um, one of the

0:22:07.066,0:22:15.866
things that maybe you noticed when we were [br]looking at the definitions, um, I have an acid [br]and a base; OK? I have an acid and a base, [br]alright?

0:22:15.866,0:22:24.066
Um, every time that we have a reaction, we [br]always have a reaction between an acid and [br]an a base, ‘cause something has to donate,

0:22:24.066,0:22:33.332
something has to accept. OK? The other [br]thing, though, about our acid-base reactions [br]we figured out in the last chapter, a lot of

0:22:33.333,0:22:41.433
our reactions are technically reversible, OK? [br]Um, sometimes the reverse reaction isn’t very [br]favorable, but our reactions

0:22:41.433,0:22:46.933
are reversible. OK? And so, um,

0:22:46.933,0:23:01.999
we start out with an acid-base, and if we’re [br]gonna reverse our reaction, then the proton is [br]going

0:23:02.000,0:23:18.366
BACK, and so our products are also an acid [br]and a base. Alright? So, if we

0:23:18.366,0:23:31.466
look at one of these reactions, OK, if we look [br]at, say the, um, ammonia reacting with the [br]water, OK? Um, we said that we

0:23:31.466,0:23:43.166
made ammonium ion and we made hydroxide, [br]OK? Um, actually I’m gonna do this on the [br]next page. Alright, so, um, our

0:23:43.166,0:23:55.632
ammonia and our water going to make [br]ammonium ion and hydroxide. So we said, in [br]the forward reaction, what happened was that

0:23:55.633,0:24:07.499
the water donated a proton to the, um, [br]ammonia, and so the water donates it acts as [br]an acid; the ammonia accepts

0:24:07.500,0:24:16.633
so it acts as a base. OK? However, if I’m [br]going to do the reverse reaction, OK, I have to

0:24:16.633,0:24:24.599
give that proton back, so now NH4 plus is [br]donating a proton, so IT acts as an acid;

0:24:24.600,0:24:29.766
the hydroxide accepts, so it acts as a base, [br]alright? So, on the

0:24:29.766,0:24:34.932
reactant side we have an acid and a base, on [br]the products side we have an acid and a base.

0:24:34.933,0:24:48.299
OK? If I pair up my base on my reactive side [br]with my acid on the product side, um, I have [br]NH3 and NH4

0:24:48.300,0:25:00.833
plus, OK? One is a base, one is an acid, the [br]only difference between the two is an H plus. [br]OK? If I look at the other pair, I have a water

0:25:00.833,0:25:13.633
that’s an acid, I have a hydroxide that is a [br]base. OK? Again, one is a reactant, one is a [br]product, one is an acid, one is a base, um, [br]and again if I

0:25:13.633,0:25:22.899
look at the two, the only difference is that [br]there’s just that one H plus that’s going back [br]and forth, OK? And so these are my conjugate

0:25:22.900,0:25:34.433
acid-base pairs that I get from the Bronsted-[br]Lowry definition: one of them is the NH3

0:25:34.433,0:25:41.899
-NH4 plus, the other pair is the water and the [br]hydroxide. And so one of the things that we get [br]from the Bronsted-Lowry definition

0:25:41.900,0:25:53.266
is we get these conjugate acid-base pairs in [br]all of our reactions. OK? So, as example, [br]gonna put a couple of these in here,

0:25:53.266,0:26:02.366
what I want you to do is identify what are the [br]conjugate acid-base pairs in these two [br]reactions. So which one is the acid,

0:26:02.366,0:26:11.032
which one is the base? (Sound effect) oops, if [br]I write it right…HCO3 minus…which one is the [br]acid, which one is the base, on

0:26:11.033,0:26:22.633
each side, and what is the acid-base pairs? [br]OK? So, take

0:26:22.633,0:26:37.966
a couple minutes here, and do that, and when [br]you’re done, start it back up and we’ll go over [br]it. (Sigh) Alright.

0:26:37.966,0:26:43.832
So, the first one: carbonate and water make [br]bicarbonate and hydroxide, OK?

0:26:43.833,0:26:49.733
It helps to pick one of the compounds, um, [br]and then look and see how it changes on the [br]other side.

0:26:49.733,0:26:56.733
So if I start out with CO3 here, OK, I have [br]CO3; the other side the thing that has carbon

0:26:56.733,0:27:05.266
is HCO3. So what I do, this starts out without [br]hydrogen, it gets hydrogen, so that means we [br]must be accepting,

0:27:05.266,0:27:17.366
‘cause it picked something up, so that means [br]it acts as a base and my water acts as an [br]acid because it is giving it up. OK? On the [br]other

0:27:17.366,0:27:25.566
side, um, what I have, ah, here I have the [br]hydrogen, I need to get rid of it to

0:27:25.566,0:27:33.332
go back to the other side. So I need to give this [br]one up. So I’m donating, and so this is my [br]acid;

0:27:33.333,0:27:40.299
hydroxide, maybe obviously, is going to be my [br]base, OK? Um, so one pair

0:27:40.300,0:27:53.466
is carbonate and bicarbonate, the other pair is [br]again water and hydroxide, OK? Alright, [br]second reaction.

0:27:53.466,0:27:59.232
I have acetate and nitrous acid. Um, going to [br]make acetic

0:27:59.233,0:28:10.033
acid and nitrite. OK? So again, I’m gonna [br]look and see which things are similar; I have [br]C2H3O2 HC2H3O2, so that is going to be one [br]of my pairs.

0:28:10.033,0:28:14.766
Don't know which one is the acid or the base [br]yet, but they only

0:28:14.766,0:28:19.532
differ by a proton, so I know that that is one of [br]my pairs, and then the other one that

0:28:19.533,0:28:28.733
has nitrogen is going to be my other pair. OK, [br]so those are my pairs, which one is the acid, [br]which one is the base? This one starts out [br]without a

0:28:28.733,0:28:36.966
hydrogen, winds up with a hydrogen, so this [br]one is accepting so it’s my base. My nitrous [br]acid is my acid, it is donating.

0:28:36.966,0:28:42.399
On the reverse side, um, that needs to lose [br]this hydrogen, so this is

0:28:42.400,0:28:47.833
the acid, the nitrite is going to be my base [br]because it’s going to pick up that hydrogen.

0:28:47.833,0:29:00.866
OK? So this is my Bronsted-Lowry definition [br]of an acid and a base. OK? And again, more [br]generic, it covers a LOT more situations, OK.

0:29:00.866,0:29:13.032
I have one more definition of an acid and a [br]base, OK, and that is the Lewis acid and base [br]definition. OK?

0:29:13.033,0:29:29.933
Now, this one is going to be the most generic. [br]OK? And it rises in situations where we need [br]to get rid of the hydrogen as well.

0:29:29.933,0:29:37.999
Alright, (sigh) an example of this. Um, if I have [br]a metal oxide, OK, sodium oxide;

0:29:38.000,0:29:51.033
metal oxides are known to be basic. OK. Um, [br]non-metal oxides, like SO3 here, are acidic, [br]OK.

0:29:51.033,0:29:59.733
where we get things like our acid rain, we have [br]nitrous oxides and sulfur oxides, um, these [br]are acidic oxides, OK.

0:29:59.733,0:30:06.866
So I have something that I know is a basic [br]oxide, if I put it in water I get a base. [br]Something that I know is an acidic oxide, if I

0:30:06.866,0:30:19.299
put it in water I get an acid. If I take these two [br]and add them together, what I get is, I get

0:30:19.300,0:30:28.366
sodium sulfate, which is neutral. OK? So [br]again, take a base and an acid and I’ve [br]combined them together to get a neutral salt.

0:30:28.366,0:30:35.366
This is your classic acid-base reaction, but I [br]don’t have any hydrogens. OK? Um,

0:30:35.366,0:30:43.599
so I can’t use the Arrhenius Equation, I can’t [br]use the Bronsted-Lowry definition, how am I [br]going to define this as an acid or a base? OK.

0:30:43.600,0:30:54.233
This is where Lewis came in. OK? Lewis. You [br]have learned about Lewis when we talked [br]about Lewis structures back in 1061.

0:30:54.233,0:31:02.633
Gilbert N. Lewis is the dude who came up with [br]Lewis structures, and so, when we’re doing [br]Lewis structures

0:31:02.633,0:31:07.966
we were looking at valence electrons, and [br]where those valence electrons were, OK? And

0:31:07.966,0:31:23.766
so this is what he did with the acid-base [br]reaction, was he looked at electrons. OK? So, [br]again,

0:31:23.766,0:31:36.299
looking at our generic acid, OK, um, and our [br]generic base, OK. Here we’re going to actually [br]draw the Lewis structure of a hydroxide, OK.

0:31:36.300,0:31:49.033
Um, but what is going on in terms of our [br]electrons when we are doing an acid-base [br]reaction? What Lewis figured out was that the [br]electrons

0:31:49.033,0:31:56.633
were going from the hydroxide to the H plus to [br]create this coordinate covalent bond.

0:31:56.633,0:32:14.199
OK, and so what he said was that an acid is [br]something that accepts electrons, OK, a base [br]is therefore going to be something that [br]donates

0:32:14.200,0:32:37.733
electrons. OK. So an acid either has to have [br]or can make – AH – empty orbitals in order to [br]pick up those electrons.

0:32:37.733,0:32:48.533
A base has to have lone pair electrons in order [br]to donate them. OK? And so this now [br]becomes our

0:32:48.533,0:32:57.433
most GENERIC definition, OK? An acid is [br]something that can accept electrons, a base [br]is something that can donate electrons.

0:32:57.433,0:33:06.633
So with our Sodium Oxide and our Sulfur [br]Trioxide, OK. What we have, if we get rid of [br]the sodium because that’s just floating around,

0:33:06.633,0:33:26.133
is we have oxide with a negative two charge, [br]um, that is our base, OK. And we’re combining [br]it with Sulfur Trioxide. OK.

0:33:26.133,0:33:33.766
Right now the Sulfur Trioxide does not have, [br]um, really an empty orbital, but what it can do [br]is,

0:33:33.766,0:33:42.199
it can pick up those pair of electrons and when [br]it does that, um, it can rearrange – OK, it can [br]dump ‘em out, sulfur can have an expanded

0:33:42.200,0:33:50.666
octet. Um, and what we get is we get the [br]sulfate ion, OK? Um,

0:33:50.666,0:34:00.766
so. This is…the sulfur functions as our acid

0:34:00.766,0:34:05.899
because it can accept the lone pair electrons, [br]um, the oxide is our base. OK? Again,

0:34:05.900,0:34:12.400
this is a real GENERIC definition, the most [br]generic definition that we have acids and [br]bases.

0:34:12.400,0:34:18.933
Um, we don’t use it most of the time, a lot of [br]times we do have our H pluses floating [br]around, and it’s easier to think about

0:34:18.933,0:34:26.899
the H pluses and where they’re going. Um, the [br]Lewis definition is often used, um,

0:34:26.900,0:34:43.065
with complex ions. OK. Complex ions are [br]metal ions that have things stuck on ‘em, like, [br]water,

0:34:43.065,0:35:00.632
ammonia, cyanide, things like that, OK? Um, [br]so, for example, ah, if we had silver ion [br]combining with NH3

0:35:00.633,0:35:16.266
we can make, um, AgNH3 two plus, OK. Or I [br]could take something like Boron Hydroxide [br]and

0:35:16.266,0:35:28.499
add water to it, and in doing that get Boron [br]with four Hydroxides and H plus. Alright?

0:35:28.500,0:35:37.933
So, um, in both of these cases, using the [br]Lewis definition, what is going to be our acid? [br]What is going to be our base?

0:35:37.933,0:35:50.766
Alright? So, what is going to be our acid, what [br]is going to be our base? We need to think [br]about electrons. OK. Silver ion? Probably [br]doesn’t have

0:35:50.766,0:35:58.132
a whole lot of electrons, OK? Ammonia, [br]though, NH3, there are lone pair electrons on [br]that nitrogen,

0:35:58.133,0:36:09.633
OK, so those lone pair electrons can attack, [br]so… our NH3 DONATES electrons, so it is a [br]base;

0:36:09.633,0:36:22.633
silver ACCEPTS electrons, and so it is going [br]to be an acid. OK? With my boron hydroxide, if [br]you think about it, boron we said before,

0:36:22.633,0:36:29.666
likes to have three things stuck to it and it has [br]this empty p orbital on it. My

0:36:29.666,0:36:36.699
water has two lone pair electrons that can go [br]fill that empty p orbital, to create the fourth

0:36:36.700,0:36:49.166
bond. So, my boron ACCEPTS lone pair [br]electrons so it is going to be an acid, the water [br]DONATES so it is going to be a base. OK,

0:36:49.166,0:36:55.099
and after it donates one of the hydrogens just [br]falls off and that’s our extra hydrogen floating [br]around here. Alright.

0:36:55.100,0:37:00.400
So those are our three definitions of acids and [br]bases. Um,

0:37:00.400,0:37:05.700
the Arrhenius definition, an acid is something [br]that increases the concentration of H plus

0:37:05.700,0:37:14.666
in water; a base increases the hydroxide [br]concentration. Um, works really well in water, [br]but pretty much just in water.

0:37:14.666,0:37:25.532
Um, the Arrhenius definition we have, um, our [br]acids that donate protons, our bases that [br]accept protons and for

0:37:25.533,0:37:33.133
those we have our conjugate acid-base pairs [br]that we have to worry about, and our [br]amphiprotic species; their most generic [br]definition is the

0:37:33.133,0:37:42.133
Lewis acid and base definition that looks at the [br]electrons. Um, acids accept lone pair [br]electrons, bases donate lone pair electrons.

0:37:42.133,0:37:51.066
Alright? And so those are our definitions of [br]acids and bases.