NAMING & WRITING FORMULAS FOR ACIDS
RULES AND PRACTICE
ACIDS
Information: Acids are covalently bonded molecules that ACT like ionic compounds. In fact, sometimes they
are classified as ionic compounds.
 Hydrogen in ALWAYS the cation (so it comes first in the formula.) This is how we identify them as acids!
 Acids are named by their ANIONS. There are 3 types of anions in the acids we will study.
1. Anions that are elements. Ex: F, S, O
2. Polyatomic anions that end it “-ate.” Ex: sulfate, SO4 23. Polyatomic anions that end in “-ite” Ex: sulfite, SO3 2PART I: NAMING ACIDS- Let’s look at the rules for naming acids in the table below.
Type of anion
Element
Polyatomic “-ate”
Polyatomic “-ite_
Naming Rule (root of
ion name is placed
on blank line)
Hydro___ic acid
_____ic acid
_____ous acid
Sample
Ion
Sample Ion
Name
Sample Acid Name
ClClO3ClO2-
Chloride
Chlorate
Chlorite
HydroCHLORic acid
CHLORic acid
CHLORous acid
PART II: WRITING FORMULAS - When you are given the name of an acid, you must be able to write the
formula.
RULES FOR WRITING FORMULAS FOR ACIDS
Step 1: Write the cation. IT’S ALWAYS HYDROGEN!
Step 2: Write the anion. USE THE NAME & CONSIDER THE NAMING RULES, ABOVE, TO FIND THE
ANION.
Step 3: Drop & swap.
Step 4: Check the ratio of cation:anion & reduce, if necessary.
Example: hydrosulfuric acid.
Step 1: H+
Step 2: the name starts with “hydro-“, so the anion MUST be the element that has the root “sulf-“. This would
be sulfur, S2Step 3: H2S
Step 4: 2:1 ratio cannot be reduced. You are done!
PART III: PRACTICE NAMING ACIDS & WRITING FORMULAS
1. sulfuric acid _________________
2. nitrous acid _________________
3. hydrochloric acid _____________
4. hypochlorous acid _____________
5. phosphorous acid ______________
6. nitric acid ____________________
7. hydrofluoric acid ______________
8. acetic acid____________________
9. HBr ____________________________________
10. H3PO4 _________________________________
11. HC2H3O2 _______________________________
12. H2CO3 _________________________________
13. HF ___________________________________
14. HClO4_________________________________
15. H3PO3_________________________________
16. H2SO3_________________________________