1. Determining the Strengths of Acids and Bases
Objectives:
1. Define the term dissociation constant and explain what it indicates about and acid or a base
2. Explain what happens when acids and bases are mixed together.
Vocabulary
acid dissociation constant, base dissociation constant, salt hydrolysis reaction

2. Strength of Acids/Bases
The strength of acids and bases are based on the amount of ions they form in solution. There properties are based on the amount of dissociation and are tied to the dissociation constant of the acid or base.

3. Acids
Strong acids
Strong acids almost completely dissociate their H+ ions in solution.
1M HCl produces 1M of H+ and Cl- in solution
HCl + H2O g H3O+ + Cl-
The dissociation constant is greater than 1. (Ka > 1)
Ka = [H+][Cl-]/[HCl] > 1
its conjugate base (Cl-) is a weak base
Weak Acids
Weak acids release very few H+ ions in solutions
1M H2CO3 produces much less than 1M of H+ in solution
H2CO3 + H2O g H3O+ + HCO3-
The dissociation constant is less than 1. (Ka < 1)
Ka = [H+][HCO3-]/[H2CO3] < 1 (4.5 x 10-7)
its conjugate base (HCO3-) is a strong base

4. Bases
strong bases almost completely dissociate to form OH- ions in solution.
1M NaOH produces 1M of Na+ and OH- in solution
NaOH + H2O g Na+ + OH-
The dissociation constant is greater than 1. (Kb > 1)
Kb = [Na+][OH-]/[NaOH] > 1
its conjugate acid (Na+) is a weak acid
weak bases dissociate to form few OH- ions in solution.
1M HF produces much less than 1M of OH- in solution
The dissociation constant is greater than 1. (Kb < 1)
Kb = [H+][OH-]/[HF] < 1
its conjugate acid (H+) is a strong acid

5. Formation of Salts from Neutralization
Acid-Base Properties of Salts
Strong Acid + Strong base g Salt + Water (pH = 7)
Strong Acid + Weak base g Salt + Weak Acid (pH < 7)
Weak Acid + Strong base g Salt + Weak Base(pH > 7)