Ch 14 Key
NVCC AL Campus CHM 112 Worksheet Chapter 14: Chemical Equilibrium Q1. Name:________________________ Write the equilibrium expression for following reactions. Hint: what happens to liquids and solids in these expressions? 1) SO2 (g) + NO2 (g) SO3(g) + NO (g) πΎπ = 2) 5 Fe2+ (aq) + MnO4- (aq) + 8 H+ (aq) 5 Fe3+ (aq) + Mn2+ (aq) + 4 H2O (l) πΎπ = 3) CO32- (aq) + 2 H+ (aq) [πΉπ 3+ ]5 [ππ2+ ] [πΉπ 2+ ]5 [πππ4 β ][π» + ]8 H2O (l) + CO2 (g) πΎπ = 4) N2O3 (g) For the reaction: 2 SO2 (g) + O2 (g) Kp = 1.23 At 298 K, Kc = 1.3 × 10-2 for the reaction: 2 NO (aq) + Br2 (g) 2 NOBr (g) What is the value of Kc for the following reaction? NOBr (g) [πΆπ3 2β ][π» + ]2 NO (aq) + ½ Br2 (g) Kc = 8.8 [ππ][ππ2 ] [π2 π3 ] 2 SO3 (g) , Kc = 30.0 at 25 C What is Kp for the reaction at the same temperature? Q3. [πΆπ2 ] NO (g) + NO2 (g) πΎπ = Q2. [ππ3 ][ππ] [ππ2 ][ππ2 ] NVCC AL Campus CHM 112 Worksheet Q4. Consider the equilibrium reaction H2 (g) + I2 (g) 2 HI (g); Kc= 50.5 A vessel contains 0.010 M HI, 0.0050 M H2 and 0.015 M I2. Is this mixture at equilibrium? Nope! If not, then which direction will the reaction proceed to attain equilibrium? To the right (more products) Q5. For the reaction: CO (g) + H2O (g) CO2 (g) + H2 (g) , Kp = 4.0 An equilibrium mixture was found to contain 0.60 atm CO, 0.20 atm of steam, and 0.50 atm CO2. What is the equilibrium partial pressure of H2 in this mixture? PH2 = 0.96 atm NVCC AL Campus CHM 112 Worksheet Q6. Given the following information, CoO(s) + H2 (g) Co (s) + H2O (g) Kc = 67 CoO(s) + CO (g) Co (s) + CO2 (g) Kc =490 Calculate Kc for the following reaction: 2H2 (g) + 2CO2 (g) 2CO (g) + 2H2O (g) Kc = 0.019 Q7. Consider the reaction: NH4HS (s) NH3 (g) + H2S (g), Kc = 1.2 x 10ο4. What are the equilibrium concentrations of NH3 and H2S if a solid sample of NH4HS is placed in a reaction vessel and decomposes until equilibrium gets established? [NH3] = 0.011 M [H2S] = 0.011 M NVCC AL Campus CHM 112 Worksheet Q8. Consider the equilibrium reaction N2O4 (g) ΞH° = 58.0 kJ 2 NO2 (g) In which direction will the equilibrium shift when the following changes are made? Explain your reasoning. (A) N2O4 (g) is added? Right (B) NO2 (g) is removed? Right (C) The volume of the reaction vessel is increased? Right (D) The temperature is decreased? Left (E) The total pressure is increased by adding some N2 (g) No change Q9. Consider the following equilibrium 6CO2 (g) + 6 H2O(l) C6H12O6 (s) + 6 O2(g) ΞH = 2816 kJ How will each of the following changes affect the equilibrium yield of C6H12O6. Explain your reasoning. 1) Increasing Pressure of CO2 More C6H12O6 2) Increasing temperature More C6H12O6 3) Removing CO2 Less C6H12O6 4) Decreasing the volume of the reaction vessel No effect 5) Removing part of C6H12O6 (s) No effect 6) Adding a catalyst No effect NVCC AL Campus CHM 112 Worksheet Q10. A 7.24 g sample of IBr is placed in a 0.225 L vessel and heated to 500. K. The following reaction takes place. 2 IBr (g) I2 (g) + Br2(g) At equilibrium, the partial pressure of Br2 is 3.01 atm. Calculate Kp for this reaction. Kp = 68 Calculate Kc for the same reaction. Kc = 68 Q11. Consider the reaction 2 SO3 (g) 2 SO2 (g) + O2 (g) In an experiment, SO3 (g) at 1.0 atm was placed in an empty reaction vessel. After equilibrium was established, the vessel contained 0.60 atm of SO2 (g). Calculate Kp for the reaction. Kp = 0.68 NVCC AL Campus CHM 112 Worksheet Q12. Consider the reaction. 2NO2 (g) 2NO (g) + O2 (g) A 0.240 mol sample of NO2 was placed in an empty 2.00-L flask at 700 K. At equilibrium, the flask contained 0.179 mol of NO2. Calculate Kc for the reaction. Kc = 0.00177 or 1.77 × 10-3 Q13. Consider the following reaction PCl5 (g) ο PCl3 (g) + Cl2 (g) ΞH° = +87.9 kJ In which direction will the equilibrium be shifted by the following changes? a) Adding PCl3 Left b) Removing Cl2 Right c) Removing PCl5 Left d) Adding a catalyst No change e) Increasing the temperature of the reaction mixture Right f) Adding He gas to the reaction mixture at constant volume g) Decreasing the volume of the reaction vessel Left No change NVCC AL Campus CHM 112 Worksheet Q14. At 600 K, Kp = 4.10 × 10-3 for the following reaction COCl2 (g) CO (g) + Cl2 (g) Calculate the equilibrium pressures of all the components in the system if the starting pressure of COCl2 was 0.124 atm. PCOCl2 = 0.103 atm PCO = 0.0206 atm PCl2 = 0.0206 atm Q15. For the reaction 2 NO2 (g) 2 NO (g) + O2 (g), Kp = 6.5×10-6 at 450 C. If a reaction vessel at this temperature initially contains 0.500 atm of NO2, what are the pressures of all species at equilibrium? PNO2 = 0.49 atm PNO = 0.015 atm PO2 = 0.0074 atm
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