Overview
This lecture covers the systematic rules for naming acids and writing their chemical formulas, focusing on patterns for different ion endings and exceptions.
Naming Acids: General Rules
- Identify the ion present (polyatomic or monoatomic) after removing hydrogen from the acid formula.
- If the anion ends in -ide, add the prefix "hydro-", change the suffix to "-ic," and add "acid."
- If the anion ends in -ate, change the suffix to "-ic" and add "acid" (no "hydro-").
- If the anion ends in -ite, change the suffix to "-ous" and add "acid" (no "hydro-").
Naming Practice Examples
- HClO₃: Contains chlorate (ClO₃⁻), becomes "chloric acid."
- HClO₂: Contains chlorite (ClO₂⁻), becomes "chlorous acid."
- HCl: Contains chloride (Cl⁻), becomes "hydrochloric acid."
- HNO₃: Contains nitrate (NO₃⁻), becomes "nitric acid."
- HNO₂: Contains nitrite (NO₂⁻), becomes "nitrous acid."
Exceptions and Notable Examples
- H₂SO₄: Sulfate (SO₄²⁻) becomes "sulfuric acid" (not "sulfate acid").
- H₂SO₃: Sulfite (SO₃²⁻) becomes "sulfurous acid."
- H₂S: Sulfide (S²⁻) becomes "hydrosulfuric acid."
Writing Acid Formulas from Names
- Replace "-ic acid" with "-ate" to get the polyatomic ion from the acid name.
- Add enough H⁺ ions to balance the charge of the polyatomic or monoatomic ion.
- Example: "Carbonic acid" becomes H₂CO₃ (carbonate is CO₃²⁻, need 2 H⁺).
- "Phosphorous acid" becomes H₃PO₃ (phosphite is PO₃³⁻, need 3 H⁺).
- "Hydrobromic acid" uses bromide (Br⁻), so formula is HBr.
Key Terms & Definitions
- Polyatomic ion — An ion made of multiple atoms with a net charge.
- Monoatomic ion — An ion consisting of a single atom with a charge.
- -ide — Suffix for single-element anions (e.g., chloride); use "hydro-" prefix and "-ic" suffix for acids.
- -ate — Suffix for polyatomic ions with more oxygen; use "-ic" suffix for acids.
- -ite — Suffix for polyatomic ions with less oxygen; use "-ous" suffix for acids.
Action Items / Next Steps
- Review and memorize common ions and their names.
- Practice naming acids and writing formulas using the given rules.
- Check provided resources for more naming practice and examples.