HW5_Solutions

# HW5_Solutions - estrada(gse77 – Homework 5 – Sutcliffe...

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Unformatted text preview: estrada (gse77) – Homework 5 – Sutcliffe – (52410) 1 This print-out should have 19 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 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. left ← correct 2. no net shift 3. → right 4. You must know the actual volume to tell. 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. → right correct 4. no net shift 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. less; less; greater 2. equal; less; greater correct 3. greater; greater; less 4. greater; less; equal 5. greater; greater; equal 6. equal; greater; greater 7. less; greater; equal 8. equal; greater; less 9. greater; equal; less 10. equal; less; less Explanation: 004 10.0 points What happens to the concentration of NO 2 (g) when the total pressure on the equi- librium reaction 2 Pb(NO 3 ) 2 (s) ⇀ ↽ 2 PbO(s) + 4 NO 2 (g) + O 2 (g) is increased (by compression)? 1. increases 2. decreases correct 3. Unable to determine 4. remains the same Explanation: estrada (gse77) – Homework 5 – Sutcliffe – (52410) 2 Increasing the total pressure on the sys- tem by decreasing its volume will shift the equilibrium toward the side of the reaction with fewer numbers of moles of gaseous com- ponents. If the total number of moles of gas is the same on the product and reactant sides of the balanced chemical equation, then changing the pressure will have little or no ef- fect on the equilibrium distribution of species present. 005 10.0 points What is the effect of a volume decrease on the reaction C(s) + H 2 O(g) → CO(g) + H 2 (g)? 1. More H 2 O(g) are produced. correct 2. no change 3. K decreases. 4. More CO(g) and H 2 (g) are produced. 5. K increases....
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## This note was uploaded on 03/03/2012 for the course CH 302 taught by Professor Holcombe during the Spring '07 term at University of Texas.

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HW5_Solutions - estrada(gse77 – Homework 5 – Sutcliffe...

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