- Most chemical rxns are reversible
- Reactants combine to give products
- Products breakdown to give reactants
Le Chatelier's Principle
- When Dynamic Equilibrium is disturbed, it will react to reestablish equilibrium
- Nature likes being in equilibrium
- Changing concentration, temp, etc. disturbs equilibrium
- The system will adjust forward/backward until equilibrium
What happens as K increases?
Reactions tends to favor Products
What happens as K decreases?
Reaction tends to favor starting materials
What is a Bronstead Acid
Proton (Hydrogen Ion) Donor
What is a Bronstead Base
Proton (Hydrogen Ion) Acceptor
When an acid donates a proton, it becomes its Conjugate Base
H (acid) --> H+ + A- (Conjugate Base)
When a base accepts a proton, it becomes its Conjugate Acid
B (base) + H+ --> BH+ (conjugate acid)
What can behave as either an acid or a base?
Amphoteric / Amphiprotic Species
The stronger the acid the ______ the conjugate base
The weaker the acid, the ________ the conjugate base
Weak Acids in Water
Weak acids do NOT ionize 100% in water
Weak bases and water
Weak bases establish equilibrium by accepting a proton from water
Resists changes in pH
May contain weak acid and its conjugate base
Equation used to determine ratio of weak acid to its conjugate base at a given pH
When concentration of weak acid equal conjugate base, the pH = pKa
What happens to weak acids as pH falls?
Become more nonionized
What happens to weak bases as pH increases?
Weak bases become more nonionized
pKa of Drugs
The pKa of a weak acid or weak base is the pH at which 50% is ionized and 50% is nonionized
Weak Acid Drugs
Weak Base Drugs
Salt + Drug = Acid or Base?
EX: Sodium pentobarbital