1. Chemistry Unit 5: Chemical Names & Formulas B-Level Lecture
Naming Acids
Chemistry
Unit 5: Chemical Names & Formulas
B-Level Lecture

2. Objectives Write the names of acids from their chemical formulas.
Write the chemical formulas of acids from their names.

3. What Are Acids?
An acid is a compound that produces hydrogen ions (H+) when dissolved in water.
Acids usually take the form H“X” where “X” is an anion (either monatomic or polyatomic)
Example: HCl
Hydrogen chloride when pure
Hydrochloric acid when dissolved in water

4. Writing Names From Formulas
The name of an acid depends on the ending of the anion
To locate the anion, “separate” the formula between the hydrogen(s) and the “rest” of the formula.
The “rest” of the formula is the anion

5. Practice Identifying Anions
HCl
Cl  Cl- = chloride ion
H2SO3
SO3  SO32- = sulfite ion
HNO3
NO3  NO3- = nitrate ion

6. Naming Acids: Rule 1 If the name of the anion ends in –ide… HCl
Cl  Cl- = chloride ion
The name begins with the prefix hydro-
The anion changes its ending to –ic
The hydro ic is followed by the word acid
hydrochloric acid

7. Naming Acids: Rule 2 If the name of the anion ends in –ite… H2SO3
SO3  SO32- = sulfite ion
The anion changes its ending to –ous
The ous is followed by the word acid
sulfurous acid

8. Naming Acids: Rule 3 If the name of the anion ends in –ate… HNO3
NO3  NO3- = nitrate ion
The anion changes its ending to –ic…
The ic is followed by the word acid
nitric acid

9. Practice Name the following acids: HF HClO H3PO4 hydrofluoric acid
hypochlorous acid
ClO hypchlorite
phosphoric acid

10. Writing Formulas From Names
The Three Rules work in reverse…
If the acid ends in –ic AND starts with hydro- then the anion ending was –ide.
If the acid ends in –ous then the anion ending was –ite.
If the acid ends in –ic then the anion ending was –ate.

11. Acids Contain Anions!!
Because acids are “ionic”, you have to make sure the overall charges balance when writing the formula!
Use the name of the acid to determine the name of the anion
Use the name of the anion and either the Periodic Table OR the Golden Sheet to determine the symbol(s) and charge of the anion
Remember that the symbol and charge of the hydrogen ion is H+1
Determine the number of hydrogen ions and anions are required to make the overall charges balance
Write the formula for the acid

12. Acid Formulas: Rule 1
If the name of the acid starts with –hydro and ends in –ic…
hydrochloric acid
The name of the anion was chloride
The symbol and charge for chloride is Cl-1
The symbol and charge for hydrogen is H+1
It will only take one H and one Cl to balance the overall charges
HCl

13. Acid Formulas: Rule 2 If the name of the acid ends in –ous…
sulfurous acid
The name of the anion was sulfite
The symbol and charge for sulfite is SO32-
The symbol and charge for hydrogen is H+1
It will only take two H and one SO3 to balance the overall charges
H2SO3

14. Acid Formulas: Rule 3 If the name of the acid ends in –ic… nitric acid
The name of the anion was nitrate
The symbol and charge for nitrate is NO3-
The symbol and charge for hydrogen is H+1
It will only take one H and one NO3 to balance the overall charges
HNO3

15. Practice Write the formula for the following acids: hydrobromic acid
arsenic acid
nitrous acid
HBr
AsO4 3-; SO3 2-
H3AsO4
HNO2

16. Processing Activity Naming Acids Anion Ending Example Acid Name -ide
Cl-
chloride
hydro-(stem)-ic acid
hydrochloric acid
-ite
SO32-
sulfite
(stem)-ous acid
sulfurous acid
-ate
NO3-
nitrate
(stem)-ic acid
nitric acid

17. Write your summary and questions now