Acids Nomenclature

Let’s deal with these compounds now, many must have heard about acids at some point, on a movie, or in jokes; but everything points to their destructive capability.
The following acids are Oxacids, as they have oxygen in their structure; there is another kind of acids, the hydroacids that only have the Non-Metal and the Hydrogen.

Acids are formed when Non-Metal Oxides (also known as Anhydrides) react with Water.

SO₃      +       H₂O     ------>      H₂SO₄

Acid formulas are a bit tricky to make, but with a little practice it becomes very easy.
First as usual, I'm going to start with the formula writing structure:

H Non-Metal O

As you can see the Hydrogen comes first, then the No-Metal and the Oxygen is last.
Most of the Acids have only subscripts on the Hydrogen and Oxygen but some rare have it on the No-Metal aswell.

H_A Metal_C O_B

There are many ways to figure out the subscripts; I'm going to teach you the easiest one in my opinion.

Write down the elements in the correct order. (2 examples)

H S O                                              H Cl O

  

Now check the valence of the No-Metal you are going to use, is it an EVEN or ODD number. (For valences check this page: Valences)

• If it is EVEN ---->the HYDROGEN’s SUBSCRIPT is 2
• If it is ODD ---->the HYDROGEN’s SUBSCRIPT is 1

            

S ---> Ox # = +2 +4 +6 (Let’s do the formula for the valence +4) H2 S O

Cl ---> Ox # = +1 +3 +5 +7 (Let’s do the formula for the valence +3) H1Cl O   There's no need to write the subscript if its 1

Now here is the trick part: SUM the OXIDATION NUMBER of the Non-Metal with the HYDROGEN SUBSCRIPT

  
Now take this number and divide it by 2, this is now the OXYGEN’s SUBSCRIPT; weird isn't it? but this is the best way to do it.

ACIDS NOMENCLATURE

There are 3 ways of naming Acids.

• TRADITIONAL nomenclature
• IUPAC nomenclature
• STOCK nomenclature

IUPAC and STOCK nomenclature in acids is not used frequently, as it is a bit difficult and general chemical compound markets in the most part use only the TRADITIONAL nomenclature. 

TRADITIONAL NOMENCLATURE
 
You need to learn a little system of prefixes and suffixes (for the oxidation numbers)

Hip----ous	--ous	---ic	Per-----ic
	+2	+4	+6
+1	+3	+5	+7

Note that the suffix does not depend on the number but on how many valences the element has.

EXAMPLE

Name this Acid

HClO₄

Remember how to make Acid formulas? Now we just need to go backwards to figure out which oxidation number the metal is using. Take the oxygen subscript, multiply it by 2 and subtract the Hydrogen subscript.

Now that we know which it is, let’s find the correct suffix to use. It has 4 oxidation numbers:

+1 ----> Hip-----ous

+3 ----> -ous

+5 ----> -ic

+7 ----> Per------ic

Traditional nomenclature has this writing structure:

[ELEMENT NAME][SUFFIX] Acid

So we just need to fill the name of the Non-metal and the suffix

PerChloric Acid

Coming up! Acids Exercises