Equilibrium Jot down the answers to the following six questions Bell Work and Review Equilibrium Jot down the answers to the following six questions

1. Chemical equilibrium exists when a. no reaction occurs. b. two similar forward reactions occur. c. two opposing reactions occur at different rates. d. two opposing reactions occur at the same rate. 2. Any chemical reaction in which the products can regenerate the reactants is called a(n) double-replacement reaction. reversible reaction. single-replacement reaction. irreversible reaction.

3. At chemical equilibrium, which of the following is always true of the concentrations of reactants and products? a. all concentrations are constant. b. reactant concentration is zero. c. all concentrations are equal. d. product concentration is zero. 4. The equilibrium constant provides information on all of the following except the a. relative concentrations of reactants and products. b. equilibrium position. c. extent to which reaction proceeds to completion. d. time required to reach equilibrium.

5. A homogeneous equilibrium is one in which the substances are a 5. A homogeneous equilibrium is one in which the substances are a. evenly mixed. . B. at the same temperature. c.in the same state of matter d. equal concentrations. 6. If a change in conditions is imposed on a system at equilibrium, the equilibrium position will always remain the same. shift to favor products. shift to increase the change in conditions. d. shift to reduce the change in conditions.

Equilibrium Test Topics Concept of equilibrium Equilibrium expression, constant, calculations Q – calculate and compare to Keq to determine if a system is at equilibrium or not LeChatelier’s Principle Ksp – calculation and effects of adding a common ion

What is the concentration of a saturated silver bromide solution What is the concentration of a saturated silver bromide solution? Ksp(AgBr) = 5.4 x 10 -13. Equation: AgBr(s)  Ag 1+ (aq) + Br 1–(aq) Call Ag 1+ x; Since the concentration of bromide ions is = that of silver ions, then bromide ion is also x Equilibrium expression Ksp = [x] [x] Substitute/calculate 5.4 x 10 -13 = (x)(x) = x2 x = 7.35 x 10 -7M So the silver ion concentration and the bromide ion concentration are both 7.35 x 10 -7M in a saturated solution.

Consider the following equilibrium system: PbCl2 (s)  Pb2+ (aq) + 2Cl-(aq) Describe what happens to the solubility of PbCl2 when the following substances are added to the solution. Why? a) Pb(NO3)2 b) NaCl c) H2O d) AgNO3 e) NaBr a) decreases; add a product; shifts left to reactant b) decreases; add a product; c) No change in grams/liter solubility d) increases; Ag forms a solid with Cl; removes product; shifts to right e)increases; Pb forms a solid with Br; removes product; shifts to right