0:02 hi class this video is going to be on
0:05 acid-base reactions and solubility our
0:07 learning goals are to Define what an
0:09 acid-base reaction is and then to be
0:13 able to identify whether reaction is an
0:14 acid-base reaction
0:16 we're also going to identify common
0:19 acids and bases
0:21 so there's going to be some vocabulary
0:24 associated with acid-base reactions
0:26 first an acid-base reaction is one in
0:29 which we have the transfer of a hydrogen
0:33 ion this would be h plus it's going to
0:35 be transferred from one chemical species
0:37 to another so you can think of it as
0:39 being transferred from one reactant to
0:43 the other reactant and an acid is going
0:46 to be a substance that when dissolved in
0:50 water yields hydronium ions h3o plus so
0:53 we can look at an example here we have
0:56 hydrochloric acid as our example which
0:58 we'll learn is a strong acid
1:01 and the reaction written we have
1:03 hydrochloric acid which is dissolved in
1:06 water right so it's aqueous when it
1:09 reacts with the water molecules right
1:13 H2O it actually will donate the proton
1:16 in hydrochloric acid to the water
1:20 molecule and when it does that water H2O becomes
1:21 becomes
1:26 h3o plus hydronium ions and so this is
1:28 The Telltale
1:31 way of us to identify that hydrochloric
1:34 acid is an acid and the fact that it
1:36 donates its proton
1:39 uh to water to generate these hydronium
1:42 ions and later we'll learn how we can
1:45 gauge the strength of a of an acid by
1:49 how much hydronium ions it can generate
1:51 so this is an example of an acid-base
1:54 reaction because our definition said
1:56 that an acid-base reaction is one in
1:59 which we have the transfer of h plus
2:02 hydrogen ion and that is what we're
2:05 seeing here as hydrochloric acid donates
2:12 now the previous slide said that
2:17 hydrochloric acid is a strong acid and
2:19 what that means is that every
2:22 hydrochloric acid molecule so every HCL
2:26 molecule we have in solution is going to
2:28 dissolve and react with water to undergo
2:30 this reaction
2:33 and this means that we're going to see a
2:36 complete reaction of hydrochloric acid
2:38 with water in the end there will be no
2:41 HCL together right instead we'll have
2:44 the chloride ion and the hydronium ions
2:46 left in our solution
2:50 there are a number of other strong acids
2:53 that react this way you can see this
2:56 table here lists them we've got
3:00 hydrobromic acid hydrochloric acid and
3:02 hydroiodic acid so here you can see
3:06 these are some of our hydrohalic
3:11 acids so acids made from the halogens
3:14 we also have nitric acid perchloric acid
3:18 and sulfuric acid and you can see the
3:20 way that they're written we tend to
3:23 write the hydrogen first so you can see
3:25 the hydrogen that is going to be donated
3:29 in that acid-base reaction
3:33 now if there are strong acids acids that
3:36 react completely to generate hydronium
3:40 ions there are also weak acids and these
3:43 weak acids will only partially react to
3:46 generate hydronium ions
3:49 so for a weak acid when it is dissolved
3:52 in water a large majority of the
3:54 molecules are going to remain in their
3:57 original form meaning that they're not
3:59 going to give up their hydrogen ions
4:02 they're going to stay as their molecular form
4:03 form
4:09 so an example here is acetic acid
4:13 ch3cooh right so in this case an acetic
4:17 acid this hydrogen at the end is the
4:20 hydrogen that can be donated as h plus
4:23 and this is going to be donated to the
4:27 water molecule to generate the hydronium
4:29 ions that we know are characteristic of
4:31 an acid
4:36 now uh in solution the amount of acetic
4:39 acid that actually undergoes this
4:43 reaction is only about one percent so
4:45 you can see that this is really a
4:49 limited partial reaction of acetic acid
4:52 to make hydronium ions and in contrast
4:55 to what we saw in the strong acids which
4:57 completely reacted right this is only
5:00 reacting a small amount
5:03 so we can denote this in our reaction by
5:08 writing that our reaction is only
5:11 partial by indicating the double-sided
5:13 Arrow to show us that we don't
5:15 completely go to the right to form our
5:16 products but that's some of the
5:20 reactants remain in their original form
5:23 so is this an acid-base reaction
5:26 the answer should be yes because here we
5:30 do see the donating of a proton h plus
5:34 from one reactant to another and so this
5:38 does qualify as an acid-base reaction
5:42 there are other examples of weak acids
5:45 so we said acetic acid is a common weak
5:48 acid so this is the
5:51 um the chemical structure for acetic
5:54 acid is a component that is found in
5:56 vinegar and that's often used for
6:01 cleaning and we also know of citric acid
6:03 right which is a common weak acid found
6:06 in our citrus fruits which you can see
6:09 over here on the left and this one has a
6:12 number of acidic hydrogens which it can
6:15 donate the acidic hydrogen on acetic
6:21 so now that we've talked about acids we
6:23 can also go and describe what a base is
6:26 so a base is a substance that will
6:29 dissolve in water to yield hydroxide
6:33 ions so acid molecules give us hydronium
6:36 ions and bases are going to give us
6:39 hydroxide ions so we have an example
6:43 reaction written for sodium hydroxide
6:46 so when this is dissolved in water it
6:50 can dissociate into its ions to give us
6:54 sodium ions and the hydroxide ions that
6:57 are characteristic of a base
7:00 so a lot of our common bases are ionic
7:04 compounds composed of our Alkali or
7:07 alkaline earth metals right so our group
7:10 one and group two metals that are with
7:15 hydroxide ions right so sodium hydroxide
7:17 which is shown here is one example of
7:19 that it would be an Alkali Earth metal
7:22 right the sodium which is present with
7:25 the hydroxide ions so other examples we
7:28 could have potassium hydroxide or
7:30 calcium hydroxide or barium hydroxide
7:33 right these being some of our group two
7:35 alkaline earth metals
7:39 so all of these bases are called strong
7:41 bases because they are going to
7:44 completely dissociate in solution so for
7:48 every one mole of strong base that you
7:51 dissolve in water you will generate one
7:55 mole of hydroxide ions right we'll have
8:01 so we say this reaction is complete you
8:04 can notice that our arrow is a single
8:06 Arrow so that tells us that it's going
8:08 to go completely in the right direction
8:11 that it is not partial now our question
8:14 is this an acid base reaction the answer
8:24 and we said that our definition of an
8:26 acid-base reaction is one in which we
8:30 have the transfer of a proton so here we
8:33 do not have any transfer taking place
8:36 instead the sodium hydroxide right this
8:39 ionic compound is just dissociating into
8:42 its constituent ions breaking apart into
8:46 the sodium ion and the hydroxide ion so
8:53 now if we have strong bases we should
8:55 have learned now that we will also have
8:59 weak bases some of the compounds that
9:04 are weak bases will react with water to
9:07 produce our hydroxide ions meaning that
9:09 the hydroxide ion isn't present
9:11 initially as part of the base but
9:13 instead upon reacting with water it will
9:16 generate the hydroxide ions
9:20 so an example is seen of this ammonia
9:25 ammonia is NH3 right we have learned how
9:27 to draw ammonia
9:30 using our Lewis structures and Vsepr
9:32 theory uh thinking about what that
9:34 structure looks like
9:38 um the nitrogen in ammonia can react
9:41 with water to um
9:44 to accept a proton from the water and
9:47 you can see we go from having NH3 to
9:51 having nh4 plus right ammonium
9:54 so when that does that we see that the hydrogen
10:00 [Music]
10:02 when that happens we see that the a
10:05 hydrogen from the water is actually
10:09 being donated to the ammonia and when
10:12 that happens we generate ammonium now
10:15 the water having given up one of its
10:19 hydrogens will then be left as hydroxide
10:22 ions and so this is what classifies
10:26 ammonia as a base in this case is this
10:29 an acid-base reaction yes right we said
10:32 that we see a hydrogen ion being
10:35 transferred from the water to the
10:38 ammonia to form our ammonium ion and
10:44 now lastly we can have something called
10:46 a neutralization reaction a
10:49 neutralization reaction is a specific
10:52 type of acid-base reaction where our
10:56 reactants are acid and base right so you
10:58 would think of a neutralization reaction
11:00 the acid and the base are neutralizing
11:01 each other
11:04 and the products of this reaction are
11:07 always consistently going to be salt and water
11:08 water
11:12 so here we have an example where we have
11:15 magnesium hydroxide so this is our base
11:19 which is reacted with hydrochloric acid
11:22 right so this is our one of our acids
11:25 and so they are reacting together to
11:27 neutralize each other and the product of
11:30 the reaction is going to be a salt so
11:32 here we see that the magnesium chloride
11:36 is the salts and then finally water is
11:38 our second product
11:40 so here we have a neutralization
11:43 reaction between an acid and a base and
11:45 I should also qualify that a
11:48 neutralization reaction we can't have
