Unit 3

Le Chatellier’s Principle

equilibrium

Q > K = too many products, equilibrium will shift toward reactants

Q < K = too many reactants, equilibrium will shift toward products

K (solubility)

K > 1 = lots of dissolved products

K < 1 = lots of undissolved reactants

Acids

Strong Acids [HA]

• large Ka, small pea

• Give a lot of H+

• acidic ph < 7

Weak Acid:

• small Ka, large -ka

• does not give a lot of H+

pH = -log[H+]

Bases

Strong base [OH-]

• large Ka, small pka

• get a lot of H+

Weak base:

• small Ka, large pKa

• doesn’t get a lot of H

pOH = -log[OH-]

Conjugate Acid Base Pair

acid = gives proton

base = reactant that gains proton

conjugate acid = product formed when acid loses its proton

conjugate base = product formed when base gained proton

Kb or Ka

Kb = 10^-pkb

Ka = 10^-pka

Buffer

• equivalence point

• pka = ph at ½ equivalence point

Indicators

• Indicators will show up based on the pka or ph.

• If the surroundings is acidic it will show up as its acid.

• If the surroundings is basic it will show up as its conjugate base.

Equations

pH + pOH = 14

Ka x Kb = 1.0 × 10^-14

pH = -log(H)

pH = -log(Ka)

pOH = -log(OH-)

pOH = -log(Kb)