CHEMICAL EQUILIBRIUM 1. Calculate Kc for each reaction.
a. I2(g)→2I(g) Kp = 6.26 ×10-22 (at 298 K)
b. CH4(g) + H2O(g)→CO(g) + 3 H2(g) Kp= 7.7 x 1024 (at 298 K)
2. Calculate Kp for each reaction.
a. N2(g) + 3H2(g)→2NH3(g) Kc = 3.7× 108 (at 298 K)
b. N2(g) + O2(g)→2NO(g) Kc = 4.10 ×10-31(at 298 K)
3. Write an equilibrium expression for each chemical equation involving one or more solid or
liquid reactants or products.
a. 2 KCIO3(s)→2 KCI(s) + 3O2(g)
b. HF(aq) + H2O(I)→H3O+(aq) + F-(aq)
4. Consider the reaction:
CO(g) + 2H2(g)→CH3OH(g)
An equilibrium mixture of this reaction at a certain temperature has [CO] = 0.105 M, [H2] = 0.114 M, and [CH3OH] = 0.185 M. What is the value of the equilibrium constant (Kc) at this temperature?
5. Nitrogen dioxide reacts with itself according to the reaction:
2NO2(g)→N2O4(g) Kp = 6.7 at 298 K. A 2.25-L container contains 0.055 mol of NO2 and 0.082 mol of N2O4 at 298 K. Is the reaction at equilibrium? If not, in what direction will the reaction proceed?
6. Consider the reaction and the associated equilibrium constant:
aA(g) + bB(g)→cC(g) Kc = 5.0
Find the equilibrium concentrations of A, B, and C for each value of a, b, and c. Assume that the initial concentrations of A and B are each 1.0 M and that no product is present at the beginning of the reaction.
a. a = 1; b = 1; c = 2
b. a = 1; b = 1; c = 1
c. a = 2; b = 1; c = 1 (set up equation for x; don’t solve)
7. This reaction is exothermic:
C6H12O6(s) + 6O2(g)→6CO2(g) + 6H2O(g)
Predict the effect (shift right, shift left, or no effect) of increasing and decreasing the reaction temperature. How does the value of the equilibrium constant depend on temperature?
8. Write an expression for the equilibrium constant of each chemical equation: a. SbCl5(g)→SbCl5(g) + Cl2(g)
b. 2BrNO(g)→2NO(g) + Br2(g)
9. Each reaction is allowed to come to equilibrium, and then the volume is changed as indicated. Predict the effect (shift right, shift left, or no effect) of the indicated volume change.
a. CO(g) + H2O(g)→CO2(g) + H2(g) (volume is decreased) b. PCl3(g) + Cl2(g)→PCl5(g) (volume is increased)
10 a Consider the reaction:
NH4HS(s) NH3(g) + H2S(g)
At a certain temperature, Kc = 8.5 x 10-3. A reaction mixture at this temperature containing solid NH4HS has [NH3] = 0.166 M and [H2S] = 0.166 M. Will more of the solid form, or will some of the existing solid decompose as equilibrium is reached?
b. Consider the reaction:
2H2S(g) 2H2(g) + S2(g) Kp = 2.4 x 10-4 at 1073 K
A reaction mixture contains 0.112 atm of H2, 0.055 atm of S2, and 0.445 atm of H2S. Is the reaction mixture at equilibrium? If not, in what direction will the reaction proceed?