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Unformatted text preview: Version 098 Exam 2 rowland (53210) 1 This printout should have 29 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. Remember that in the Kp to Kc conversion problems Quest refers to Kp as K and Kc as Kc. 001 10.0 points At 700 K, K = 54 for the reaction H 2 (g) + I 2 (g) 2 HI(g) . Calculate K c at 700 K for this reaction. 1. 3 . 2 10 4 2. 0.94 3. 0.45 4. 54 correct 5. 7 . 7 10 4 Explanation: 002 10.0 points A certain reaction has H equal to 11.57 kJ/mol. This reaction is normally run at room temperature (25 C). At what new tem perature should the reaction be run so that K is twice its value at 25 C? 1. 135 C 2. 31 C 3. 65 C 4. 50 C 5. 77 C correct 6. 94 C Explanation: T 1 = 25 C +273 = 298 K K 2 = 2 K 1 H = 11570 J/mol ln K 2 K 1 = H R parenleftbigg 1 T 1 1 T 2 parenrightbigg R H ln K 2 K 1 = 1 T 1 1 T 2 T 2 = parenleftbigg 1 T 1 R H ln K 2 K 1 parenrightbigg 1 = parenleftbigg 1 298 8 . 314 11570 ln 2 parenrightbigg 1 = 349 . 94 K = 77 C 003 10.0 points Write the reaction quotient for 3 ClO (aq) 2 Cl (aq) + ClO 3 (aq) . 1. Q c = [Cl ] 2 [ClO 3 ] [ClO ] 3 correct 2. Q c = [ClO 3 ] [ClO ] 3 [Cl ] 3. Q c = [ClO ] 3 [Cl ] 2 [ClO 3 ] 4. Q c = [ClO 3 ] 2 [ClO ] [Cl ] 3 5. Q c = 2 [Cl ] [ClO 3 ] 3 [ClO ] Explanation: Q c = activities of products activities of reactants , where the subscript c indicates the activities are given in terms of molarities: a J = [J] 004 10.0 points When the reaction CO 2 (g) + H 2 (g) H 2 O(g) + CO(g) is at equilibrium at 1800 C, the equilib rium concentrations are found to be [CO 2 ] = 0.24 M, [H 2 ] = 0.24 M, [H 2 O] = 0.48 M, and [CO] = 0.48 M. Then an additional 0 . 67 moles per liter of CO 2 and the same amount of H 2 are added. When the reaction comes to Version 098 Exam 2 rowland (53210) 2 equilibrium again at the same temperature, what will be the molar concentration of CO? 1. . 653 M 2. . 927 M correct 3. . 733 M 4. . 867 M 5. . 813 M Explanation: [CO 2 ] = 0.24 M [H 2 ] = 0.24 M [H 2 O] = 0.48 M [CO] = 0.48 M K = [H 2 O] [CO] [CO 2 ] [H 2 ] = (0 . 48 M) (0 . 48 M) (0 . 24 M)(0 . 24 M) = 4 After the addition of the CO 2 and H 2 , [CO 2 ] ini = 0.24 M + 0 . 67 M = 0 . 91 M [H 2 ] ini = 0.24 M + 0 . 67 M = 0 . 91 M CO 2 (g) + H 2 (g) H 2 O(g) + CO(g) . 91 . 91 0.48 0.48 x x + x + x . 91 x . 91 x . 48 + x . 48 + x (0 . 48 + x )(0 . 48 + x ) (0 . 91 x )(0 . 91 x ) = 4 . 48 + x . 91 x = 4 = 2 . 48 + x = 2(0 . 91 x ) = 1 . 82 2 x 3 x = 1 . 34 x = 0 . 446667 [CO] = (0 . 48 + x ) M = 0 . 926667 mol / L 005 10.0 points Given the following equilibrium data at 973 K MgCl 2 (s) + 1 2 O 2 (g) MgO(s) + Cl 2 (g) K p = 2 . 95 atm MgCl 2 (s) + H 2 O(g) MgO(s) + 2 HCl(g) K p = 8 . 40 atm Calculate the equilibrium constant K p...
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 Fall '07
 Madrid

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