Naming Acids Tutorial
Acids are a group of compounds that, when
dissolved in water, all have very similar properties.
They all have low pH values; they all react with
metals; they all dissolve carbonate compounds…
And they all taste sour!
Here is a list of some common acids:
HCl, H2SO4, HNO3, HC2H3O2, H2CO3, HF, H3PO4.
What do you notice about all these compounds?
Hopefully you noticed that they all start with “H.”
In solution, these H’s break off as H+ ions, and it is
these hydrogen ions that are responsible for
making the solution behave as an acid.
Naming Acids Tutorial
But how are acids named?
Actually, the process is quite simple… if you already
know how to name regular ionic compounds.
All you do is make two easy changes to the name:
1) Drop the word “hydrogen” in the beginning and
replace it with the word “acid” at the end.
2) Change the suffix (ending) of the negative ion:
If it ends in “–ate,” change it to “-ic.”
If it ends in “–ite,” change it to “-ous.”
If it ends in “–ide,” change it to “hydro- -ic.”
That’s it! (Write these steps down in your notes right
now, so you will have them to refer to for the next slides.)
Naming Acids Tutorial
Let’s try a few examples:
What would be the regular ionic name for HNO3?
Hopefully you knew the answer is:
Now change the “hydrogen” hydrogen
acid nitric
nitrate
in the beginning to “acid” at
the end.
Then change the “-ate” ending to “-ic.”
Thus the correct acid name is
“nitric acid.”
Nitric acid is a very strong, corrosive
acid that is capable of dissolving copper!
Naming Acids Tutorial
Let’s try a few examples:
What would be the regular ionic name for HClO4?
Hopefully you knew the answer is:
Change the “hydrogen” hydrogen
acid perchloric
perchlorate
in the beginning to “acid”
at the end.
Then change the “-ate” ending to “-ic.”
Thus the correct acid name is
“perchloric acid.”
Perchloric acid is even stronger than
nitric acid, and it is used in the
production of rocket fuel.
Naming Acids Tutorial
Let’s try another example:
What would be the regular ionic name for HBrO2?
Hopefully you knew the answer:
Change the “hydrogen” hydrogen
acid bromite
bromous
in the beginning to “acid”
at the end.
Then change the “-ite” ending to “-ous.”
Thus the correct acid name is
“bromous acid.”
Although we can name this acid, chemists have
never been able to actually isolate bromous acid.
It is just too unstable to exist!
Naming Acids Tutorial
Let’s try another example:
What would be the regular ionic name for HClO?
Hopefully you knew the answer:
Change the “hydrogen” hydrogen
acid hypochlorous
hypochlorite
in the beginning to “acid”
at the end.
Then change the “-ite” ending to “-ous.”
Thus the correct acid name is
“hypochlorous acid.”
Because it is so effective at killing
bacteria, hypochlorous acid is used
as a disinfectant in swimming pools.
Naming Acids Tutorial
Let’s try another example:
What would be the regular ionic name for HF?
Hopefully you knew the answer:
Change the “hydrogen” hydrogen
acid
hydrofluoric
fluoride
in the beginning to “acid”
at the end.
Then change the “-ide” ending to “hydro- -ic.”
Thus the correct acid name is “hydrofluoric acid.”
HF is capable of dissolving glass – or etching it:
Designs like the one at right are made by placing tape
over portions of the glass, then dipping it in a solution
of hydrofluoric acid. The exposed areas get that frosted
look, while the taped-over parts remain clear.
Naming Acids Tutorial
Now it’s your turn. Try naming the following acids:
“(aq)” stands for aqueous, and it means that these compounds are dissolved in water.
1. HBrO4(aq)
2. HBr(aq)
3. HC2H3O2(aq)
4. HNO2(aq)
5. HIO(aq)
6. H2CO3(aq)
7. HCN(aq)
8. H2Cr2O7(aq)
9. H3PO3(aq)
10. H2SO4(aq)
Naming Acids Tutorial
In case you were having difficulty, here are their regular ionic names:
1. HBrO4(aq) hydrogen perbromate
hydrogen bromide
2. HBr(aq)
3. HC2H3O2(aq) hydrogen acetate
4. HNO2(aq) hydrogen nitrite
hydrogen hypoiodite
5. HIO(aq)
6. H2CO3(aq) hydrogen carbonate
hydrogen cyanide
7. HCN(aq)
8. H2Cr2O7(aq) hydrogen dichromate
9. H3PO3(aq) hydrogen phosphite
10. H2SO4(aq) hydrogen sulfate
Naming Acids Tutorial
And so these would be the correct acid names:
1. HBrO4(aq) perbromic acid
About the last two
hydrobromic acid acids: You probably
2. HBr(aq)
thought they would be
acetic
acid
(AKA:
vinegar!)
3. HC2H3O2(aq)
“phosphous acid” and
4. HNO2(aq) nitrous acid
“sulfic acid,” but they
are not. Perhaps for
hypoiodous acid
5. HIO(aq)
2- used to
example
SO
4
6. H2CO3(aq) carbonic acid
be called “sulfurate,”
hydrocyanic acid
7. HCN(aq)
and then it got
shortened to “sulfate,”
8. H2Cr2O7(aq) dichromic acid
but the acid name
phosphorous
acid
9. H3PO3(aq)
stayed “sulfuric” – who
10. H2SO4(aq) sulfuric acid
knows???
Naming Acids Tutorial
Now try going the other way: Write the correct
formulas for the following five acids
1. Chromic acid
2. Hydroiodic acid
3. Boric acid
4. Citric acid (citrate = C6H5O73-)
5. Permanganic acid
Naming Acids Tutorial
These are the answers you should have come up
with:
1. Chromic acid
H2CrO4
2. Hydroiodic acid HI (it’s a friendly acid!)
3. Boric acid
H3BO3
4. Citric acid
H3C6H5O7
5. Permanganic acid HMnO4
Notice that it’s not only important to write down the
correct formula for the ions, but it’s also important to
balance the charges. For example, because H1+ has a 1+
charge and CrO42- has a 2- charge, it took 2 H’s to balance
the charge on the one CrO4. Hence: H2CrO4