1. Definitions of Acids and Bases
Chemistry
Mrs. Coyle

2. Vinegar (acetic or ethanoic acid)
Common Acids
Vinegar (acetic or ethanoic acid)
Citric Acid

3. Characteristics of Acids
Sour taste (for edible acids)
May burn your skin
Turn litmus paper from blue to red.

4. Examples of Acids HCl Hydrochloric Acid H2SO4 Sulfuric Acid
HNO3 Nitric Acid
CH3COOH Acetic Acid (Vinegar)

5. Common Bases
Ammonia

6. Characteristics of Bases
Bitter taste (for edible bases only)
Can be poisonous and corrosive.
Turn litmus from red to blue.

7. Examples of Bases Sodium Hydroxide NaOH Potassium Hydroxide KOH
Magnesium Hydroxide Mg(OH)2
Ammonia NH3

8. Three Definitions of Acids and Bases
Svante Arrhenius (Swedish 1887)
Bronsted- Lowry (Danish and English 1923 independently proposed definition)
Gilbert Lewis (American 1920’s)

9. Arrhenius Definition of Acids and Bases
Acids produce hydrogen ions (H+) in an aqueous solution, while bases produce hydroxide ion (OH-).
Acid: HCl (aq) H+ (aq) + Cl- (aq)
Base: NaOH(aq) Na+(aq) + OH-(aq)

10. Acids can have more than one ionizable hydrogen.
Number of Ionizable Hydrogens
Monoprotic 1
Diprotic 2
Triprotic 3

11. Bronsted- Lowry Definition of Acids and Bases
An acid is a proton (H+) donor.
A base is a proton (H+) acceptor.
Example:
HF + H2O H3O+ + F-
Acid Base
H3O+ : hydronium ion

12. Conjugate Acids and Bases
General expression:
HA (aq) + H2O (l) H3O+ (aq) + A- (aq)
Acid Base Conjugate Conjugate
Acid Base

13. Conjugate Acids and Bases
Conjugate acid is the particle formed that has received the proton. (ex: H3O+)
Conjugate base is the particle left from the acid once it has donated the proton.

14. Ammonia NH3(aq) + H2O (l)  NH4 + (aq) + OH- (aq)
Base Acid Conjugate Conjugate
Acid Base

15. Note
Water acts as an acid and as a base. It is amphoteric.

16. Lewis Acids and Bases An acid accepts a pair of electrons.
A base donates a pair of electrons.
This is a more general definition than the previous two.

17. Example of a Lewis Acid and Base
:NH3 + H+  NH4+

18. Three Models of Acids and Bases
Definition of Acid
Definition of Base
Arrhenius
H+ producer
OH- producer
Bronsted-Lowry
H+ donor
H+ acceptor
Lewis
Electron-pair acceptor
Electron-pair donor