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Unformatted text preview: So (dds785) Homework 4 Sutcliffe (52440) 1 This print-out should have 25 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. Refer to the notes published on Blackboard regarding Lewis acids and bases. 001 (part 1 of 2) 10.0 points Consider the reaction 22 . 1 kcal + PCl 5 (g) PCl 3 (g) + Cl 2 (g) How does the equilibrium shift if the vol- ume of the container is decreased? 1. You must know the actual volume to tell. 2. left correct 3. right 4. no net shift Explanation: A volume decrease is the same as a pressure increase. The equilibrium will shift to the side with the fewest gas moles which is to the left. Also, the value of Q would be greater than K so the reaction would shift left. 002 (part 2 of 2) 10.0 points How does the equilibrium shift when temper- ature is increased? 1. It depends on whether it is on the Kelvin or Celsius scale. 2. left 3. no net shift 4. right correct Explanation: Because the reaction is ENDOthermic, an increase in temperature would push the reaction forward. The equilibrium constant would increase as a result. 003 10.0 points Each of the following reactions occurs in a 1.0 liter container and is at equilibrium. A(g) + B(g) 2 C(g) a) 3 A(g) + B(g) 2 D(g) b) 2 A(g) 2 C(g) + D(g) c) If the volume in each container is reduced by one-half, will the Q c be greater than, less than, or equal to the K c for each reaction? The answers are in order of a, b, and c. 1. equal; greater; less 2. greater; greater; less 3. less; greater; equal 4. equal; less; greater correct 5. greater; greater; equal 6. equal; greater; greater 7. greater; equal; less 8. less; less; greater 9. equal; less; less 10. greater; less; equal Explanation: 004 10.0 points Note: Some of you may need to consider the definition of BOND ENERGY to answer this question. Predict whether the equilibria I) CH 4 (g) + H 2 O(g) CO(g) + 3 H 2 (g) , H = +206 kJ II) CO 2 (g) + 2 NH 3 (g) CO(NH 2 ) 2 (s) + H 2 O(g) , H =- 90 kJ will shift toward products or reactants with a temperature increase. 1. Unable to determine 2. I shifts toward products and II shifts to- ward reactants. correct So (dds785) Homework 4 Sutcliffe (52440) 2 3. Both I and II shift toward products. 4. Both I and II shift toward reactants. 5. I shifts toward reactants and II shifts toward products. Explanation: If a reaction is exothermic, raising the tem- perature will tend to shift the reaction toward reactants; whereas if the reaction is endother- mic, a shift toward products will be observed. Reaction I is endothermic (+ H ); raising the temperature should favor the formation of products. Reaction II is exothermic; raising the temperature should favor the formation of reactants....
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