Equilibrium Worksheet

Equilibrium Worksheet o 1. Given KC is 50.2 for the following reaction at 445 C. 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 30 2NO(g)  N2(g) + O2(g) KC = 2.4 x 10 NO(g) + 1/2 Br2(g)  NOBr(g) KC = 1.4 3. Determine KC from the KP values given -2 A) SO2Cl2(g)  SO2(g) + Cl2(g) KP = 2.9 x 10 at 303 K 2 B) NO(g) + 1/2 O2(g)  NO2(g) KP = 1.2 x 10 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 KC for the vaporization process? o 5. The value of KC is 0.0900 at 25 C 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. o 7. When 1.00 mol of I2(g) is introduced into a 1.00 L container at 1200 C 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? o 9. The Value of KP at 25 C 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? o 10. H2 at 1.75 atm and O2 at 0.75 atm are placed in a container at 200 C. A spark causes reactio to form H2O (g). At equilibrium the total pressure is 1.90 atm. A) Calcualte KP. B) calculate KC.

o 11. At 2200 C, 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. o H2(g) +I2(g) 2HI(g) KC = 69 at 340 C 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. -3 o N2O4(g)  2NO2(g) KC = 4.61 x 10 at 25 C Determine the percent dissociation if 0.0240 mole of N2O4 is allowed to come to equilibrium in a 10.0 L container. -4 o 14. The equilibrium constant, KP, for the following reaction is 4.00x10 at 500 C.

2HCN(g)  H2(g) + C2N2(g) o What is the equilibrium partial pressure of C2N2(g) at 500 C if HCN was originally present at 25 atm? o 15. Consider the decomposition of COBr2 at 73 C.

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. o -5 17. At 35 C, KC = 1.6x10 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: 3+ 2+ 2+ 2+ [Fe ] = [Hg2 ] = 0.5000 M; [Fe ] = [Hg ] = 0.03000 M The following reaction occurs among the ions at a certain temperature. 3+ 2+ 2+ 2+ -8 2Fe (aq) + Hg2 (aq)  2Fe (aq) + 2Hg (aq) KC = 9.14 x 10 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; -3 -2 4: KC = 1.28 x 10 ; 5: A) shift left; B) equilibrium; C) shift left; 6: 0.13; 7: A) 1.1 x 10 , 3 B) 1.3; 8: [HI]=0.0267 M, [I2]=0.00793 M; 9: 1.21 atm; 10: A) 32, B) 1.2x10 ; -2 11: 7.8x10 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, 3+ 2+ 2+ [NO]=0.050 M, [Cl2]=1.0 M; 18: [Fe ] = 0.5193 M, [Hg2 ] = 0.5096 M , [Fe ] = 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