1. ACIDS AND BASES

2. Define acids and bases in terms of the three definitions:
Arrhenius
Bronsted and Lowry
Lewis
Define Amphoteric
Identify and label conjugate pairs.

3. ACIDS BASES Taste bitter Feel slippery Turn red litmus blue
Taste sour
Burn when touching skin.
Turn blue litmus red.
Neutralize basic solutions.
Corrosive to metals
strong or weak electrolytes
BASES
Taste bitter
Feel slippery
Turn red litmus blue
Neutralize acidic solutions
strong or weak electrolytes

4. Acids – Compounds that yield hydrogen ions (H+) in aqueous solution.
Arrhenius Definition
Acids – Compounds that yield hydrogen ions (H+) in aqueous solution.
Bases – Compounds that yield OH- ions in aqueous solution.
Svante Arrhenius ( )
yes, this is really him...looks happy, eh?

5. HCl (aq) → H+ (aq) + Cl– (aq)
NaOH (aq) → Na+ (aq) + OH– (aq)

6. NH3 ~ no OH– ? The Bronsted-Lowry Theory 20 years later:
base
Lowry
~ no OH– ?
The Bronsted-Lowry Theory
20 years later:
An acid is a proton (H+) donor.
A base is a proton (H+) acceptor.
Bronsted

7. NH3 (g) + H2O(l) NH4+(aq) + OH-(aq) Base is a proton (H+) acceptor:
Ammonia accepts a proton from water: H+
NH3 (g) + H2O(l)
NH4+(aq) + OH-(aq)
acceptor

8. H+ and H3O+ are written interchangeably.
Acids is a proton (H+) donor: H+
HCl (g) + H2O(l)
H3O+(aq) + Cl-(aq)
donor
acceptor
Result is the H3O+ ion called the hydronium ion.
H+ and H3O+ are written interchangeably. H+
NH3 (g) + HCl(g)
NH4+(g) + Cl-(g)

9. Bicarbonate ion is also amphoteric.
A substance which can act as either an acid or a base is described as being amphoteric.
Water is amphoteric.
Bicarbonate ion is also amphoteric. H+
HCO OH-
CO H2O
donor
acceptor H+
HCO H2O
H2CO3 + OH-
acceptor
donor

10. Gilbert Lewis Definition
Acids and bases accept and donate electrons, NOT protons.
Lewis acids accept (keep) electrons.
Lewis bases donate (lose) electrons. H+
CH3COO-(aq) + H2O(l) OH-(aq) + CH3COOH (aq)
base
acid

11. Transition metal ions with charges of 2+ or 3+, create an acidic solution with water.
Step 1: Formation of a hydrate.

12. Step 2: Loss of H+ making acidic solution.
Fe(H2O)63+ + H2O  H3O+ + Fe(H2O)5(OH)2+ H+ H

13. NH3 (g) + H2O(l) NH4+(aq) + OH-(aq)
Conjugate acid is what remains after a base has accepted a proton.
Conjugate base is what remains after the acid has donated its proton.
NH3 (g) + H2O(l)
NH4+(aq) + OH-(aq)
base
acid
Con. acid
Con. base

14. B + H2O BH+ + OH- HA + H2O H3O+ + A- Each is called a conjugate pair.
base
acid
Con. acid
Con. base
HA H2O
H3O A-
acid
base
Con. acid
Con. base

15. Arrhenius defined acids as substances which release H+ ions in water and bases as substances which release OH¯ ions in water.
Bronsted and Lowry defined acids as proton donors and bases as proton acceptors.
Substances that behave as BOTH acids and bases, these are called amphoteric.
An acid and its conjugate base or a base and its conjugate acid are known as conjugate pairs.

16. CAN YOU / HAVE YOU?
Define acids and bases in terms of the three definitions:
Arrhenius
Bronsted and Lowry
Lewis
Define Amphoteric
Identify and label conjugate pairs.