1. Acid/Base Strength 1 1 1 1 1

2. How Strong is an Acid?
Concentration is always a factor in the strength of an acid, but we’re going to define ‘strength’ by how intrinsically strong or weak the molecule is:
HA ⇆ H+ + A-
The more this equilibrium favors the products, the stronger the acid is. 2 2 2 2 2

3. Strong or Weak? HA ⇆ H+ + A- Strong: Ka > 1
We will just assume all HA becomes products.
Strong acids are: HCl (and HBr/HI) HNO3
H2SO HClO4 (rare) 3 3 3 3 3

4. Strong or Weak? HA ⇆ H+ + A- Weak: Ka < 1
There is a real equilibrium happening here.
Weak acids are: Anything not explicitly strong 4 4 4 4 4

5. Strong or Weak? B- + H2O ⇆ HB + OH- Strong: Kb > 1
Again we’ll just assume this goes all the way (100%).
Strong bases are: OH-, O2-, H-, and NH2- 5 5 5 5 5

6. Strong or Weak? B- + H2O ⇆ HB + OH- Weak: Kb < 1
Again this is a real equilibrium, and there will be ICE box
Weak bases are: any base not explicitly strong 6 6 6 6 6

7. Conjugate Strengths HA ⇆ H+ + A-
The conjugate base of a strong acid is just not a base
(if it goes 100%, then there’s no tendency to go backwards)
The conjugate base of a weak acid is a weak base.
(the weaker the acid, the stronger the conjugate base)
The same applies to bases: the conjugate of a strong base is not an acid. The conjugate of a weak base is a weak acid. 7 7 7 7 7