1. Chapter 19.1 Acid-Base Theories
Chemistry I
Mrs. Ragsdale

2. Properties of Acids Taste sour – typically edible
When dissolved in water (placed in solution), they become electrolytes
Change the color of an acid-base indicator
Score anywhere from 0 – 6.9 on the pH scale

3. Properties of Bases Taste bitter – typically poisonous Feel slippery
Think soap: it feels slick and tastes very bitter
Change the color of an acid-base indicator
Also form electrolytes when placed in solution
Score anywhere from 7.1 – 14 on a pH scale

4. Common Acids and Bases Acids Bases HCl – Hydrochloric acid
HNO₃ - Nitric acid
H₂SO₄ - Sulfuric acid
H₃PO₄ - Phosphoric acid
NH₄ - Ammonium
NaOH – Sodium hydroxide
KOH – Potassium hydroxide
Ca(OH)₂ - Calcium hydroxide
Mg(OH)₂ - Magnesium hydroxide
NH₃ - Ammonia

5. Defining Acids and Bases
Three main ways to define acids and bases
Arrhenius Acids and Bases
Bronsted-Lowry Acids and Bases
Lewis Acids and Bases

6. Arrhenius Acids and Bases
Acids are hydrogen-containing compounds that ionize to yield hydrogen ions (H⁺) in aqueous solution.
Bases are compounds that ionize to yield hydroxide ions (OH⁻) in aqueous solution

7. Arrhenius Acids Can be monoprotic, diprotic, or triportic acids
Mono – HCl
Di – H₂SO₄
Tri – H₃PO₄
Release H⁺ ions in solution

8. Arrhenius Bases
Compounds that ionize in solution that yield hydroxide (OH⁻) ions

9. Bronsted-Lowry Acids and Bases
Acids are hydrogen proton (H⁺) donators
Bases are hydrogen proton acceptors
Important because Arrhenius definition leaves out acids and bases like ammonia and ammonium!

10. Conjugate Acids and Bases
When an acid donates a hydrogen proton on the left side of a reaction, it becomes a base on the right.
On the other hand when a base on the left accepts a proton, on the right it becomes an acid because it now has a hydrogen proton it can donate.
Therefore we have conjugate acid-base pairs.

11. Final Tidbits…
Hydronium ions (H₃O⁺) can be formed when acids are added to water. Hydronium ions are considered bases.
HCl(g) + H₂O (l) ↔ H₃O⁺(aq) + Cl⁻(aq)
Water is amphoteric. This means it can act as an acid or a base.
It can acts as an acid OH⁻ or as a base as H₃O⁺

12. Lewis Acids and Bases
An acid accepts a pair of electrons during a reaction while a base donates a pair of electrons

13. Putting it all together!

14. Acid-Base Definitions
Your handy dandy chart!
Acid-Base Definitions
Type
Acid
Base
Arrhenius
H⁺ producer
OH⁻ producer
Bronsted-Lowry
H⁺ donor
H⁺ acceptor
Lewis
Electron-pair acceptor
Electron pair donor