1. Chemical Equilibrium Ch.14

2. (14-1) Equilibrium Reversible rxn in which the forward & reverse rxns occur at = rates Amts. of reactants & products are constant

3. Le Chatelier’s Principle If a system at equil. is disturbed the system shifts to relieve the stress Inc. T, P, or conc. on 1 side of eq. & rxn is forced in opposite direction

5. The initial soln color (middle) is a mix of yellow & dark red colors due to the presence of both the Fe +3 & the FeSCN +2 complex. The addition of Fe +3 causes the soln to turn darker red (left) & the removal of Fe +3 causes the soln to turn yellow (right).

8. (a) Frozen N 2 O 4 is nearly colorless. (b) As N 2 O 4 is warmed it starts to dissociate into brown NO 2 gas. (c) Eventually the color stops changing as N 2 O 4 (g) & NO 2 (g) reach conc.’s at which they are interconverting at the same rate.

9. (14-2) Equilibrium Constant K eq : relates the conc.’s of reactants & products eq

11. Equil. Practice A 1 L vessel contains 1.60 mols NH 3, 0.800 mols N 2, & 1.20 mols of H 2. Calculate K eq. N 2 (g) + 3H 2 (g) 2NH 3 (g) 1.List known [NH 3 ] = 1.60, [N 2 ] = 0.800, [H 2 ] = 1.20

12. Equil. Practice 2.Write eq. K eq = _[NH 3 ] 2 [N 2 ][H 2 ] 3 3.Substitute & solve K eq = (1.60) 2 = 1.85 (0.800)(1.20) 3

13. Solubility Product Constant K sp : expression for an ionic solid in equil. w/ its ions in a saturated soln Ca 3 (PO 4 ) 2 (s) 3Ca 2+ (aq) + 2PO 4 3- (aq) K sp = [Ca 2+ ] 3 [PO 4 3- ] 2 only aq & g products

14. Solubility Practice Calculate the K sp for a 1.34 x 10 -5 M saturated soln of AgCl. AgCl(s) Ag + (aq) + Cl - (aq) 1.List known 1.34 x 10 -5 mol AgCl x 1 mol Ag + = 1.34 x 10 -5 mol Ag + 1 mol AgCl Therefore, [Ag+] = [Cl-] = [AgCl] = 1.34 x 10 -5 M

15. Solubility Practice 2.Write eq. K sp = [Ag + ][Cl - ] 3.Substitute & solve K sp = (1.34 x 10 -5 ) 2 = 1.80 x 10 -10

16. More Solubility Practice Calculate the K sp for a 6.54 x 10 -5 M saturated soln of Ag 2 CrO 4. Ag 2 CrO 4 (s) 2Ag + (aq) + CrO 4 2- (aq) K sp = [Ag + ] 2 [CrO 4 2- ] = [(2)(6.54 x 10 -5 )] 2 (6.54 x 10 -5 ) = 1.2 x 10 -12

17. Common Ion Effect Reduction in solubility of an ionic cmpd by the addition of an ion in common w/ it