How would you identify an acid from its name or formula?

Answer 1

DERIVING ACID'S NAME FROM FORMULA

In order to name an acid when given the formula, follow these steps:

1. Identify the anion. This can be done by removing or separating the hydrogen(s) from the anion via writing out the equation. The number of hydrogens is = to the anion's charge.

HX --> H+ + X

OR

H+ + Anion (Cation + Anion)

2. Name the acid. It is highly recommended to remember various polyatomic ions and such for this step. Since acids are named based on the anion, follow the guidelines below:

Anion ends with "-ide": place the prefix "hydro-" in front of the element name. Replace "-ide" with "-ic acid".

Hydro-element name-ic acid

Anion ends with "-ate": replace "-ate" with "-ic acid".

Element name-ic acid

Anion ends with "-ite": replace "-ide" with "-ous acid".

Element name-ous acid

**NOTE: If the anion involves sulfur or phosphorus, changes to the stem name will be made. Add "-ur" to the stem name if there is sulfur, or "-or" if there is phosphorus.**

Sulfur

Anion ends with "-ide": hydro-element name-uric acid

Anion ends with "-ate": element name-uric acid

Anion ends with "-ite": element name-urous acid

Phosphorus

Anion ends with "-ide": hydro-element name-oric acid

Anion ends with "-ate": element name-oric acid

Anion ends with "-ite": element name-orous acid

DERIVING FORMULA FROM ACID NAME

In order to identify the formula from the acid's name, follow these steps:

1. Identify the anion. This can be done by adjusting the name via removal of suffixes and prefixes (if applicable).

Anion starts with "hydro-", ends with "-ic acid": drop prefix and replace "-ic acid" with "ide.

Element name-ide

Anion ends with "-ic acid": replace "-ic acid" with "-ate".

Element name-ate

Anion ends with -ous acid": replace "-ous acid" with "-ite".

Element name-ite

**NOTE: If there is sulfur or phosphorus in the anion, also remove the "-ur" (sulfur) or the "-or" (phosphorus) in the ending when identifying the anion.

2. Identify the formula. Now that the anion has been identified, we can create the formula. Add cation H+ to the equation (the number of hydrogens is equal to the anion's charge). It is recommended to remember various polyatomic ions for this step.

Cation + Anion

H+ + Anion

OR

H+ + X-n--> HX