Equilibrium Worksheet
1. Given KC is 50.2 for the following reaction at 445 oC.
H2(g) + I2(g)  2HI(g)
Determine KC for the following reactions:
A)
1/2 H2(g) + 1/2 I2(g)  HI(g)
B)
HI(g)  1/2 H2(g) + 1/2 I2(g)
2. Determine KC for the following reaction at 298 K.
1/2 N2(g) + 1/2 O2(g) + 1/2 Br2(g)  NOBr(g)
Given
2NO(g)  N2(g) + O2(g)
KC = 2.4 x 1030
NO(g) + 1/2 Br2(g)  NOBr(g)
KC = 1.4
3. Determine KC from the KP values given
A)
SO2Cl2(g)  SO2(g) + Cl2(g)
KP = 2.9 x 10-2 at 303 K
B)
NO(g) + 1/2 O2(g)  NO2(g)
KP = 1.2 x 102 at 184 K
C)
Sb2S3(s) + 3H2(g)  2Sb(s) + 3H2S(g)
KP = 0.429 at 713 K
o
4. The vapor pressure of water at 25 C is 23.8 mmHg. Write KP for the
vaporization of water in the unit of atm. What is K C for the vaporization process?
5. The value of KC is 0.0900 at 25 oC for the reaction
H2O(g) + Cl2O(g)  2HOCl(g)
For which of the following sets of conditions is the system at equilibrium? For those that
are not, which direction will the system shift?
A) A 1.0 L flask containing 1.0 mol HOCl, 0.10 mol Cl2O, and 0.10 mol H2O.
B) A 2.0 L flask containing 0.084 mol HOCl, 0.080 mol Cl2O, and 0.98 mol H2O.
C) A 3.0 L flask containing 0.25 mol HOCl, 0.0010 mol Cl2O, and 0.56 mol H2O.
6. At a particular temperature, 3.0 mol of NO2 is placed in a 1.0 L container and the NO2
dissociates by the reaction
2NO2(g)  2NO(g) + O2(g)
At equilibrium, the concentration of NO2 is 2.0 M. Calculate KC for the reaction.
7. When 1.00 mol of I2(g) is introduced into a 1.00 L container at 1200 oC it is
5.0% dissociated into I(g) atoms.
A) Calculate KC.
B) Calculate KP.
8. Hydrogen iodide decomposes according to the reaction
2HI(g)  H2(g) + I2(g)
A sealed 1.50 L container initially holds 0.0623 mol H2, 0.00414 mol I2, and 0.0244 mol
HI at 703 K. When equilibrium is reached the concentration of H2 is 0.0467 M. What
are the equilibrium concentrations of HI and I2?
9. The Value of KP at 25 oC is 0.15 for the reaction
N2O4(g)  2NO2(g)
If the pressure of N2O4 at equilibrium is 0.85 atm, what is the total pressure of the gas
mixture (NO2 and N2O4) at equilibrium?
10. H2 at 1.75 atm and O2 at 0.75 atm are placed in a container at 200 oC. A spark causes
reactio to form H2O (g). At equilibrium the total pressure is 1.90 atm.
A) Calcualte KP.
B) calculate KC.
11. At 2200 oC, KP = 0.050 for the reaction
N2(g) + O2(g)  2NO(g)
What is the partial pressure of NO in equilibrium with N2 and O2 that were placed in a
flask at initial pressures of 0.80 and 0.20 atm respectively?
12. Consider the reaction below.
H2(g) +I2(g) 2HI(g)
KC = 69 at 340 oC
What is the percent dissociation of HI(g) into its elements at this temperature
when 1.00 mol of HI is introduced into a 1.0 L container?
13. Consider the reaction below.
N2O4(g)  2NO2(g)
KC = 4.61 x 10-3 at 25 oC
Determine the percent dissociation if 0.0240 mole of N2O4 is allowed to come to
equilibrium in a 10.0 L container.
14. The equilibrium constant, KP, for the following reaction is 4.00x10-4 at 500 oC.
2HCN(g)  H2(g) + C2N2(g)
What is the equilibrium partial pressure of C2N2(g) at 500 oC if HCN was originally
present at 25 atm?
15. Consider the decomposition of COBr2 at 73 oC.
COBr2(g)  CO(g) + Br2(g)
A mixture at equilibrium in a 2.00 L container contains 0.295 M CO, 0.295 M Br2, and
0.455 M COBr2. If 1.00 mole of CO is added to the system, what is the equilibrium
concentration of each compound after equilibrium is re-esatablished. Solve the problem
two different ways.
16. At 35 oC, K = 1.6 x 10-5 for the reaction
2NOCl(g)  2NO(g) + Cl2(g)
Calculate the concentrations of all species at equilibrium for each of the following
original mixtures.
A) 1.0 mole NOCl in a 1.0 L container.
B) 1.00 mol NO and 0.50 mol Cl2 in a 1.0 L container.
C) 1.00 mol NO and 0.75 mol Cl2 in a 1.0 L container.
17. At 35 oC, KC = 1.6x10-5 for the reaction
2NOCl(g)  2NO(g) + Cl2(g)
A) If 2.0 mol of NO and 1.0 mol of Cl2 are placed in a 1.0 L flask caculate the
equilibrium concentration of all species.
B) If 2.0 mol of NO and 2.0 mol of Cl2 are placed in a 1.0 L flask caculate the
equilibrium concentration of all species.
18. A solution is prepared having the following initial concentrations:
[Fe3+] = [Hg22+] = 0.5000 M; [Fe2+] = [Hg2+] = 0.03000 M
The following reaction occurs among the ions at a certain temperature.
2Fe3+(aq) + Hg22+(aq)  2Fe2+(aq) + 2Hg2+(aq)
KC = 9.14 x 10-8
What will be the ion concentrations when equilibrium is established?
19. An important exothermic reaction in the commercial production of hydrogen is
CO(g) + H2O(g)  H2(g) CO2(g)
How will the system at equilibrium shift in each of the following cases?
A) CO2 is removed.
B) H2O(g) is agged.
C) The pressure is increased by adding helium gas.
D) The temperature is increased.
E) The pressure is increased by decreasing volume.
20. Consider the endothermic reaction
CaCO3(s)  CaO(s) + CO2(g)
A) Fill in the table below showing how the indicated change to the equilibrium system
will affect the indicated quantity when a new equilibrium state is established.
Change
Quantity
Effect
Add CaO(s)
CO2
Decrease the container
CaO(s)
volume
Decrease the container
Total Pressure
volume
Add CO2
KP
Add CO2
CaCO3
Add Helium gas
CO2
Increase the temperature
CO2
Increase the temperature
KP
B) which of the above changes results in changing the value of KP?
Answers- 1: A) 7.07, B) 0.141; 2: 9.0 x 10-16; 3: A)1.2 x 10-3, B) 4.7 x 102, C)
0.429;
4: KC = 1.28 x 10-3; 5: A) shift left; B) equilibrium; C) shift left; 6: 0.13; 7: A) 1.1 x
10-2, B) 1.3; 8: [HI]=0.0267 M, [I2]=0.00793 M; 9: 1.21 atm; 10: A) 32, B) 1.2x103;
11: 7.8x10-2 atm; 12: 19%; 13: 49.3%; 14: 0.481 atm; 15: [Br2]=0.167 M, [COBr]=
0.583 M, [CO]=0.667 M; 16: A) [NOCl]=1.0 M, [NO]=0.032 M, [Cl2]=0.016 M, B)
[NOCl]=1.0 M, [NO]=0.032 M, [Cl2]=0.016 M, C) [NOCl]=1.0 M, [NO]=0.0.0080 M,
[Cl2]=0.25 M; 17: A) [NOCl]=2.0 M, [NO]=0.050 M, [Cl2]=0.025 M, B) [NOCl]=2.0
M, [NO]=0.050 M, [Cl2]=1.0 M; 18: [Fe3+] = 0.5193 M, [Hg22+] = 0.5096 M , [Fe2+] =
0.0107M, [Hg2+] = 0.0107 M; 19: A) right, B) right, C) no effect, D) left, E) no effect;
20: A) no change, decrease, no change, no change, increase, no change,
increase, increase; B) increasing temperature only
Borowski, Sp 2001