What is a generalization for determining whether an acid name will end in the suffix -ie or -ous?

1 Answer
Mar 13, 2017

The use of #"hypo"#, #"per"#, prefixes, and #"ous"# and #"ic"# endings to describe acids, their salts, and oxidation states is a bit old-fashioned..........

Explanation:

We can look at the oxyacids of chlorine, and assign an oxidation to chlorine:

#HOCl,"hypochlorous acid", Cl(+I)#;

#HOCl(=O),"chlorous acid", Cl(+III)#;

#HOCl(=O)_2,"chloric acid", Cl(+V)#;

#HOCl(=O)_3,"perchloric acid", Cl(+VII)#.

And in general, the acid/salt with the LOWER oxidation state has an #"ous"# ending; and the acid/salt with the HIGHER oxidation state has an #"ic"# ending.

The use of #"hypo"# means #"reduced"#, here with respect to oxidation state; #"per"# means #"maximum"#. These are all old-fashioned names, and depending on your syllabus, you should not have to master them. You would, however, be required to find the oxidation state of chlorine in the oxoacid.