1. Acid/ Base Definitions

2. Arrhenius Definitions
Acid – H+/H3O+ producer
Base – OH- producer
Good for strong acids and bases

3. Bronsted-Lowry Definition
Acid – proton (H+) donor
Base – proton acceptor
Accounts for some weak bases which do not have an OH-

4. Lewis Definition Acid – electron pair acceptor
Base – electron pair donor
Encompasses even more than the Bronsted-Lowry definition

5. Identify the Lewis acid and base
Ni NH3  Ni(NH3)62+
H+ + H2O  H3O+

6. Conjugate Acid/Base
In every acid/base reaction, there are actually two acids and two bases
NH3 + HF → F- + NH4+
On the reactant side, HF is an acid so it has a Ka, but on the product side F- the is a base so it has a Kb

7. Relationship Between Ka and Kb
Ka x Kb = Kw
pK = - log K
pKa + pKb =

8. Example
Calculate the Kb for the F- ion if the Ka for its conjugate acid is given in Appendix A5.1.
Calculate the Ka for the ammonium ion, NH4+.

9. Example
Calculate the pH of a .30M NaF solution. The Ka for HF is 7.2x10-4.