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Nomenclature of Inorganic Acids. Recognizing An Acid. At this very beginning level, you will recognize an acid by the fact that its formula starts with “ H ”. HCl HNO 3 H 2 SO 4 HClO 3 H 3 PO 4
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Recognizing An Acid • At this very beginning level, you will recognize an acid by the fact that its formula starts with “H”. • HCl • HNO3 • H2SO4 • HClO3 • H3PO4 (As you become more sophisticated in your chemistry, you will recognize that there are many acid formulas that do not start with H.)
Binary Acids Binary acids are made from only 2 elements. Examples: HCl, HF, HBr, HI, HCN Hey wait a minute! How did HCN get in there? HCN is the only exception to these rules and will be named using the same method as binary acids.
Naming Binary Acids All Binary acid names begin with the prefix “hydro” The prefix is followed by the root name of the anion with the suffix “ic”. Examples: chloride: chloric bromide: bromic Then add the word “acid” to the end.
Examples of Binary Acids HCl Hydrochloric Acid HF Hydrofluoric Acid HBr Hydrobromic Acid HI Hydroiodic Acid
And of course HCN Hydrocyanic Acid
Oxyacids Oxyacids contain, not only hydrogen, but also an oxygen-containing polyatomic ion. Examples: HNO3 HClO3 H2SO4 H3PO4 To name these acids it is imperative that you know your polyatomic ions!
Naming Oxyacids Example: H2SO4 Step #1:Determine the name of the polyatomic ion that is attached to the hydrogen. SO4-2 = Sulfate Step #2: If the polyatomic ion name ends with “ate”, change the ending to “ic” and add the word acid to the end of the name.
In this case, the word “sulfate” is changed to “sulfuric”. Therefore: H2SO4 = sulfuric acid
Example: H2SO3 Step #1: Determine the name of the polyatomic ion that is attached to the hydrogen. SO3-2 = Sulfite Step #2: If the polyatomic ion name ends with “ite”, change the ending to “ous” and add the word acid to the end of the name. H2SO3 = sulfurous acid
Overall Rule in Naming Oxyacids ate ic ite ous
Examples H3PO4 Phosphoric acid H2CO3 Carbonic acid HIO3 Iodic acid HNO3 Nitric acid HC2H3O2 Acetic acid
Writing Formulas of Oxyacids Again, you must know your polyatomic ions! Example: nitrous acid Step #1: From the name, determine what the polyatomic ion will be. In this example, the word “nitrous” tells us that the polyatomic ion is the “nitrite” ion, or NO2-1. (Why??? Remember… “ate” to ic, “ite” to ous!)
So now you know the anion is NO2-1. But what is the cation??? Remember… An inorganic acid’s formula always begins with “H”. But How many??? Since the hydrogen ion’s charge is +1, you will need one H+1 ion and one NO2-1 ion. The correct formula for nitrous acid is: HNO2