Acid-Base Equilibria pH and pOH Relationship of Conjugate Pair acid-base strength. When acids or bases control pH:  determine K  predict pH When pH controls acid/base state:  predict acid/base state  use acid/base state to determine pH Buffer action pH titration curves

pH/pOH Calculations [H 3 O + ][OH - ] = 1.0 x pH = -log[H 3 O + ] pOH = -log[OH - ] [H 3 O + ] = 10 -pH [OH - ] = 10 -pH pH + pOH = What is the pH of a solution with [H 3 O + ] = 4.6 x What is the pOH of a solution with [OH - ] = 3.3 x What is the pOH of a solution with [H 3 O + ] = 2.4 x What is [H 3 O + ] when pH = 4.2

Strong acids and bases For strong acid solutions, [H 3 O + ] = [acid] (except for H 2 SO 4 ) For strong bases LiOH, NaOH, KOH, RbOH, [OH - ] = [base] For strong bases Ca(OH) 2, Ba(OH) 2, etc., [OH - ] = 2 x [base]

What is the pH when [H 3 O + ] = M?

What is the pH when [OH - ] = 6.5 x M?

What is the [H 3 O + ] when pH = 3.66 M? x

What is the [OH - ] when pH = 5.84 M? x x x

Acid-Base Equilibria Bronsted Acid: H + (proton) donor Bronsted Base: H + acceptor Acid-Base reactions: H + transfer reaction Conjugate Acid-Base Pairs: acid conjugate base HFF - NH 4 + NH 3

What is the conjugage base of HNO 2 ? 1.H 2 NO HNO 3 3.NO 2 -

What is the conjugage acid of HPO 4 2- ? 1.H 2 PO H 3 PO 4 3.PO 4 3-

Acid-Base Strength: Depends on Equilibrium Constant

Trends in relative acid/base strength for conjugate pairs.

Determining the K a Value What is the value of K a for an acid, HA, for which a M solution has a pH of 3.28?

Determining K b : A M solution of a weak base has a pH of What is K b ?

What is the pH of a M solution of HCl?

What is the pH of a M solution of HF?

What is the pH of a M solution of HCN?

What is the pH of a M solution of Ca(OH) 2 ?

What is the pH of a M solution of NH 3 ?

Polyprotic Acids H 2 CO 3 HCO 3 - CO 3 2- H 3 PO 4 H 2 PO 4 - HPO 4 2- PO 4 3-