1. Review:
Predict the products of the following acid base reactions, write net ionic equations for each, and identify whether the resulting pH will be greater or less than 7 and WHY.
NaOH + HClO 
HNO3 + KH2PO4 

2. Acids, Bases and Equilibrium, Oh My!!!

3. pH and Concentrations Calculations:
For pH calculations of acids, bases and salts, it is important to know which situations are equilibrium and which are not!
Equilibrium
Not Equilibrium
1. Weak acids/bases dissociating in water
1. Strong acids/bases dissociating in water
2. Most acid-base rxn’s

4. Weak acid or base solutions:
Since these only dissociate partially, eqm is established
Use ICE tables and K expressions to solve …
Example: A 0.10 M aqueous solution of lactic acid, CH3CHOHCO2H, has a pH of What is the value of Ka for lactic acid?

5. Strong Acid or Base solutions:
Since these dissociate completely, reactions go to completion
Use stoichiometry to solve …
What is the pH of a 0.5 M HCl solution?

6. Practice:
Example: Calculate the pH of a M solution of benzoic acid (C6H5CO2H) if the Ka = 6.3x10-5

7. For polyprotic acids:
How would this process work for a polyprotic acid such as H3PO4 that has multiple dissociations?
1. H3PO4 + H2O ↔ H2PO H3O+ Ka=7.5x10-3
2. H2PO H2O ↔ HPO H3O+ Ka=6.2x10-8
3. HPO H2O ↔ PO H3O+ Ka=3.6x10-13

8. For polyprotic acids:
For most polyprotic acids, the pH only depends on the amount of H3O+ generated in the first step!
The other reactions are so reactant favored, that they barely produce any H3O+ at all
Practice: Calculate the pH of 0.020M solution of Phosphoric acid.

18. Acids and Bases