1. Acid/Base Equilibrium

2. Arrhenius’ Theory of Acids & Bases
Up until this point, you have learnt Arrhenius’ Theory:
An acid dissociates in water to produce H+(aq)
E.g. HCl(aq)  H+(aq) + Cl-(aq)
A base dissociates in water to produce OH-(aq)
E.g. NaOH(s)  Na+(aq) + OH-(aq)
However, this theory could not explain exceptions like why NH3 (ammonia) and NaHCO3 (baking soda) were considered bases

3. Bronsted-Lowry Theory of Acids & Bases
An acid is a substance which produces protons (H+), a proton donor
A base is a substance which accepts protons, a proton acceptor
Two molecules/ions that are related by the transfer of a proton are called a conjugate acid-base pair
base
conjugate acid H+
acid
conjugate base

4. Conjugate Pairs Example
Identify the conjugate acid/base pairs and show the proton transfer
acid
conjugate base H+
base
conjugate acid

5. Conjugate Pairs Example
Identify the conjugate acid/base pairs and show the proton transfer.
What is interesting about these systems?
base
conjugate acid H+
acid
conjugate base
acid
conjugate base H+
base
conjugate acid
Amphiprotic species can act as either an acid or a base. Has both an H-atom and a lone pair of electrons

6. Strong Acids and Bases Dissociate completely
Quantitative reaction, no dynamic equilibrium
Strong Acids
Strong Bases
All oxides & hydroxides of Group 1 & 2 metals except Be

7. Weak Acids and Bases
Do not dissociate completely
Dynamic equilibrium

8. Practice!
Worksheet
P. 532 #1,2