1. Lecture 122/18/05 There is class on Monday

2. Strong Bases: What is the pH of 0.01 M solution of each of the strong bases? Oxide (O 2- : CaO, Na 2 O) O 2- (aq) + H 2 O → 2 OH - (aq) Hydride (H - : NaH) H - (aq) + H 2 O → H 2 (aq) + OH - (aq) Nitride (N 3- : Na 3 Na) N 3- (aq) + 3H 2 O → NH 3 (aq) + 3OH - (aq)

3. Weak acids and bases HA + H 2 O ↔ H 3 O + + A - HF + H 2 O ↔ H 3 O + + F - A - + H 2 O ↔ HA + OH - F - + H 2 O ↔ HF + OH - NH 3 + H 2 O ↔ NH 4 + + OH -

8. CH 3 COOH (aq) + H 2 O (l) ↔ CH 3 COO - (aq) + H 3 O + (aq) K a = 1.8 x 10 -5 CH 3 COO - (aq) + H 2 O (l) ↔ CH 3 COOH (aq) + OH - (aq) K b = 5.6 x 10 -10 2 H 2 O (l) ↔ OH - (aq) + H 3 O + (aq) K w = K a K b At 25°C: 10 -14 = K a K b -log (10 -14 = K a K b ) 14 = pK a + pK b

9. What is the pH of a 0.05 M solution of benzoic acid ( C 6 H 5 COOH)? K a = 6.3 x 10 -5 at 25°C C 6 H 5 COOH ↔ C 6 H 5 COO - + H + I0.0500 C-X+X E0.05 - XXX