How can I determine the formula of an acid?

1 Answer
mrpauller.weebly.com
Oct 9, 2015

First you need to determine if the acid is binary (only H and one other element) or ternary (H and more than one other element).

Explanation:

Binary acids will have names which begin with the prefix "hydro". The ending of the name for the acid will come from the second element found in the acid.

HCl = hydrochloric
HBr = hydrobromic

Notice how chlorine changes to chloric and bromine changes to bromic.

Ternary acids do not have the prefix hydro in their names unless the polyatomic ion has a name which has the "ide" suffix. The name comes from the element listed first in the polyatomic ion (oxyanion).

H3PO4 = phosphoric acid
H3PO3 = phosphorous acid

Because H3PO4 contains the polyatomic ion phosphate, the ending for the name of the acid will be "ic".

Because H3PO3 contains the polyatomic ion phosphite, the ending for the name of the acid will be "ous".

You should memorize
"ate" goes to "ic"
"ite" goes to "ous"

Here is a video to help further with this concept.

Video from: Noel Pauller

Hope this helps!

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