#4, Assignment CHAPTER 13 Equilibrium Theory 1. Write equilibrium constant expressions (Kc) for the following: a. AgCl(s) + 2 NH3(aq) [Ag(NH3)2]+ (aq) + Cl-(aq)
K = [Ag(NH3)2+] [Cl-] [NH3]2 b. CO2(g) + C(s) 2CO(g). K = [CO]2 [CO2] 2. What is the value of Kc for the reaction 2A(g) B(g) + 2C(g) if only A is present initially and [A] at equilibrium is 30.0% of the original concentration of A, which was 2.00 M? ICE I C E A 2.00 -1.40 (.30)(2.00) = 0.6 B 0 +0.70 0.70 C 0 1.40 1.40
K = (0.70x1.402) = 3.81 0.62 3. A closed flask is set up in which only substance C is present with an initial concentration of 0.80 M. When a state of equilibrium is reached in the reaction C D + 2E, the equilibrium concentration of C is 0.20 M. What are the equilibrium concentrations of D and E? ICE I C E C 0.80 -0.60 0.20 D 0 +0.60 0.60 E 0 1.20 1.20
4. If Kc = 2.0 x 106 at 100C for the reaction 2SO2(g) + O2(g) what is the value of Kc the for reaction 2SO3(g) 2SO2(g) + O2(g)?
2SO3(g), then
K = [SO2]2 [O2] = 1/(2.0 x 106) = 5.0 x 10-7 [SO3]2
5. What are the equilibrium concentrations [I2] and [I] for the reaction I2(g) 2I(g) if the initial concentrations are 2.0 x 10-1 M I2, 0 M I, and Kc = 4.0 x 10-2? ICE I C E I2 0.20 -x 0.20-x 0.040 = (2x)2 0.20-x I 0 +2x 2x 4x2 + 0.04x -0.008 = 0 x = +0.04 ; -0.05 [I]eq = 2(0.40) = 0.80M
So [I2]eq = 0.20 -0.04 = 0.16M
6. For the reaction below, Horxn = +508 kJ. 2 POCl3(g) 2 PCl3(g) + O2(g) Indicate the direction (to reactants, to products, no change) that the equilibrium will shift when a) [POCl3] is increased __ to products ___ b) O2 is removed ____ to products ___ c) the pressure is increased by decreasing the volume ____ to reactants ___ d) a catalyst is added ____ no change _______ e) the temperature is reduced ______ to reactants ______ f) the pressure is increased by adding argon __ no change __