Homework 4-solutions

# Homework 4-solutions - phan(dtp377 – Homework 4 –...

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Unformatted text preview: phan (dtp377) – Homework 4 – sutcliffe – (51045) 1 This print-out should have 20 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. You must know the actual volume to tell. 3. no net shift 4. → right 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. → right correct 3. no net shift 4. left ← 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 What is the effect of a volume decrease on the reaction C(s) + H 2 O(g) → CO(g) + H 2 (g)? 1. More CO(g) and H 2 (g) are produced. 2. no change 3. More H 2 O(g) are produced. correct 4. K increases. 5. K decreases. Explanation: 004 10.0 points Predict whether the equilibria I) CH 4 (g) + H 2 O(g) ⇀ ↽ CO(g) + 3 H 2 (g) , Δ H ◦ = +206 kJ II) X 2 (g) ⇀ ↽ 2 X(g) , where X is a halogen will shift toward products or reactants with a temperature increase. 1. I shifts toward reactants and II shifts toward products. 2. I shifts toward products and II shifts to- ward reactants. 3. Both I and II shift toward products. cor- rect 4. Unable to determine 5. Both I and II shift toward reactants. 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 (+Δ H ); raising the temperature should favor the formation of products. Reaction II is endothermic (break- ing a bond, +Δ H ); raising the temperature should favor the formation of products....
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## This note was uploaded on 03/26/2012 for the course CHEM 302 taught by Professor Mccord during the Fall '10 term at University of Texas.

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Homework 4-solutions - phan(dtp377 – Homework 4 –...

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