1. Lecture 82/3/06

2. QUIZ 2 1. Ba(NO 3 ) 2 reacts with Na 2 SO 4 to form a precipitate. Write the molecular equation and the net ionic equation. 2. For the following reaction; S (s) + O 2 (g) ⇄ SO 2 (g) ΔH = - 296.8 KJ/mol If you raise the temperature, which direction does the equilibrium shift?

3. A saturated solution of silver oxalate (Ag 2 C 2 O 4 ) contains 6.9 x 10 -5 M of C 2 O 4 2- at 25˚C. Calculate the K sp of silver oxalate at that temperature.

4. The K sp of MgF 2 = 5.2 x 10 -11. Calculate the solubility in molarity and grams per liter.

5. Comparison of solubility based on K sp AgI (K sp = 8.5 x 10 -17 ) < AgBr (K sp = 5.4 x 10 -13 ) < AgCl (K sp = 1.8 x 10 -10 ) PbI 2 (K sp = 9.8 x 10 -9 ) < PbBr 2 (K sp = 6.6 x 10 -6 ) < PbCl 2 (K sp = 1.7 x 10 -5 ) Can only compare salts with same ion ratio AgCl (K sp = 1.8 x 10 -10 ) vs. Ag 2 CO 3 (K sp = 8.5 x 10 -12 ) Solubility of AgCl = 1.3 x 10 -5 mol/L Solubility of Ag 2 CO 3 = 1.3 x 10 -4 mol/L

6. Q vs. K sp AgBr (s) ⇄ Ag + (aq) + Br - (aq) Q = K sp Q < K sp Q > K sp

7. Le Chatelier’s review Given the following reaction: NH 4 HS (s) ⇄ NH 3 (g) + H 2 S (g)  H = + Which direction will the reaction shift if you: a. Add more NH 4 HS b. Remove NH 3 c. Decrease the temperature