HOME-WORK 3 – CHEM 1412
1. For the aqueous reaction, A + 2 B → 3 C + 4 D, I mix 1 mole of A, 2 moles of B, 1 mole of C and 2
moles of D in a 1 L container. If the equilibrium constant (Kc) at this temperature is 5, then
(A) the reaction mixture is at equilibrium
(B) the reaction will proceed to the left
(C) the reaction will proceed to the right
(D) none of these are correct
(E) the [products] will be MUCH smaller than the [reactants] at equilibrium
2. Kp at 25 °C for the reaction, NO2(g) → NO(g) + O2(g) is 4.48 x 10-13. Calculate the value for Kc.
(A) 1.81 x 10-16 (B) 1.83 x 10-14
(C) 4.48 x 10-13 (D) 1.11 x 10-9 (E) cannot be determined
3. Consider the exothermic reaction: N2(g) + 3H2(g) → 2NH3(g) ΔH = –92.1 kJ. At 400 K, the
equilibrium constant (Kc) is 0.53. Calculate Kp for the reaction at 400 K.
(A) 0.53
(B) 17.4
(C) 752
(D) 0.016
(E) 4.9 x 10-4
4. Nitric oxide and bromine were allowed to react in a sealed container, according to the equation,
NO(g) + Br2(g) → NOBr(g). At equilibrium, p(NO) = 0.526 atm, p(Br2) = 1.59 atm, and p(NOBr) =
7.68 atm. Calculate Kp for the reaction.
(A) 7.45 x 10-3
(B) 0.109
(C) 9.18
(D) 134
(E) 7.68
5. Calculate Kc for the reaction, N2(g) + 3H2(g) → 2NH3(g) when the equilibrium concentration moles
per liter are: N2 = 0.02, H2 = 0.01, NH3 = 0.10.
(A) 2 x 10–6
(B) 5 x 103
(C) 5 x 105
(D) 5 x 107
6. A 1.20-L flask contains an equilibrium mixture of 0.0168 mol of N2, 0.2064 mol of H2, and 0.0143
mol of NH3. Calculate Kc for the reaction N2(g) + 3H2(g) → 2NH3(g)
(A) 1.38
(B) 1.99
(C) 4.12
(D) 4.96
7. Under a set of equilibrium conditions [HI] = 0.10 M and [H2] = [I2]. Calculate the concentration of I2
if the equilibrium constant (Kc) = 0.016. 2HI(g)→H2(g) + I2(g)
(A) 1.3 x10–2 M
(B) 3.1 x 10–1 M
(C) 4.0 x 10–2 M
(D) 1.3 M
8. One mole of a compound AB reacts with one mole of a compound CD according to, AB + CD →
AD + CB. When equilibrium has been established it is found that 0.75 mol of each of the reactants
AB and CD has been converted to AD and CB. There is no change in volume. What is the
equilibrium constant (Kc) for the reaction?
(A) 1/9
(B) 9
(C) 9/16
(D) 16/9
9. For the endothermic reaction, CaCO3(s) → CaO(s) + CO2(g), which of the following actions would
shift the equilibrium to form more CO2 gas?
(A) increasing the temperature
(B) decreasing the temperature
(C) increasing the pressure
(D) increasing both the pressure and temperature
10. The equilibrium, PCl5(g) ⇔PCl3(g) + Cl2(g), will be shifted to the right by the
(A) addition of a catalyst. (B) removal of Cl2. (C) increase of pressure (D) removal of PCl5.
11. The equilibrium constant (Kc) for the reaction, 2HBr(g)  H2(g) + Br2(g) is 10 at a certain
temperature, when concentrations are expressed in moles per liter. Calculate the number of moles of
HBr(g), present at equilibrium if 100 L of the equilibrium mixture contain 5 mol of H2(g) and 8 mol
of Br2(g).
(A) 0.25
(B) 0.5
(C) l
(D) 2
(E) 4
12. Consider the reaction: PCl  PCl (g) + Cl (g). At a particular temperature, 0.84 moles of PCl is
5
3
2
5
placed into a 1 L flask. At equilibrium, 0.72 moles of PCl5 are present. Calculate Kc for the reaction.
(A) 0.62
(B) 0.020
(C) 0.72
(D) 0.12
(E) 50
13. Consider the vapor phase reaction, 2 HCl  H2 + Cl2, for which Kc = 16 at 523 K. If 0.030 moles of
HCl is introduced into a 1 L vessel at 523 K, what is the equilibrium concentration of H2?
(A) 0.024 M
(B) 0.013 M
(C) 0.015 M
(D) 0.24 M
(E) 0.0052 M
14. Given the exothermic reaction: N2(g) + 3H2(g) → 2NH3(g) ΔH = –92.1 kJ. At 400 K, the
equilibrium constant (Kc) is 0.53. At 800 K, what is the value of the equilibrium constant?
(A) 0.53
(B) > 0.53
(C) < 0.53
(D) dependent on [NH3]
15. Which is the correct equilibrium constant expression for the following reaction?
Fe2O3(s) + 3H2(g)
2Fe(s) + 3H2O(g)
(A) Kc = [Fe2O3] [H2]3/[Fe]2[H2O]3
(B) Kc = [H2]/[H2O]
(C) Kc = [H2O]3/[H2]3
(D) Kc = [Fe]2[H2O]3/[Fe2O3] [H2]3
(E) Kc = [Fe] [H2O]/[Fe2O3] [H2]
16. Consider the following equilibria:
Calculate the equilibrium constant for the reaction
SO2(g) + NO3(g)
SO3(g) + NO2(g).
(A) 78
(B) 1.3  10-2
(C) 1.6  10-4
(D) 3.2  10-10
(E) 6.1  103
The value of Kc for reaction: H2 (g) + I2 (g)  2HI (g); is 50.5. In what direction the reaction
proceed if the initial concentratios are as follows?
(17) [H2] = 0.015 M , [I2] = 0.012 M , [HI] = 0.024 M
(18) [H2] = 0.030 M , [I2] = 0.060 M , [HI] = 0.15 M
(19) [H2] = 0.002 M , [I2] = 0.003 M , [HI] = 0.025 M
20 For the equation: C (s) + CO2 (g)  2CO (g); the value of Kp is 167.5 at 1000 oC. If a 5.00 L
container initially contains 2.99 atm pressure of CO2 (g) at 1000 oC, what are partial pressure of CO2 (g)
and CO (g) at equilibrium?