EXAM2SOL - Moore Robert – Exam 2 – Due Mar 8 2007 noon...

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Unformatted text preview: Moore, Robert – Exam 2 – Due: Mar 8 2007, noon – Inst: McCord 1 This print-out should have 22 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points For NaNO 3 , an aqueous solution will have a pH 1. greater than 7. 2. less than 7. 3. equal to 7. correct Explanation: 002 (part 1 of 1) 10 points What is the pH of a 0 . 26 M solution of pyri- dinium chloride (C 5 H 5 NH + Cl- )? ( K b for pyridine is 1 . 5 × 10- 9 . ) Correct answer: 2 . 88055 pH. Explanation: 003 (part 1 of 1) 10 points Which of the following anions is the strongest base, according to the Bronsted-Lowry the- ory? 1. None of the anions listed is a base. 2. NO- 3 3. Cl- 4. ClO- 3 5. F- correct 6. I- Explanation: HCl, HNO 3 , HI and HClO 3 are strong acids with very weak Bronsted-Lowry bases. HF is a weak acid and an appreciable amount of it remains in solution as the unionized acid. 004 (part 1 of 1) 10 points The equilibrium constant for the reaction 4NH 3 (g) + 5O 2 (g) → 4NO(g) + 6H 2 O(g) is K . Calculate the equilibrium constant for the reaction 2NO(g) + 3H 2 O(g) → 2NH 3 (g) + 5 2 O 2 (g) . 1. 1 √ K correct 2.- K 3.- K 2 4. 1 K 5.- 2 K Explanation: 005 (part 1 of 1) 10 points The standard molar Gibbs free energy of for- mation of NO 2 (g) at 298 K is 51.30 kJ · mol- 1 and that of N 2 O 4 (g) is 97.82 kJ · mol- 1 . What is the equilibrium constant at 25 ◦ C for the reaction 2NO 2 (g) * ) N 2 O 4 (g)? 1. 7 . 01 × 10- 9 2. 1 . 02 × 10- 10 3. None of these 4. 9 . 72 × 10 9 5. 0.657 6. 6.88 correct 7. 1.00 8. 0.145 Explanation: Δ G products = 97 . 82 kJ · mol- 1 Moore, Robert – Exam 2 – Due: Mar 8 2007, noon – Inst: McCord 2 Δ G reactants = 51 . 30 kJ · mol- 1 Δ G rxn = X n Δ G products- X n Δ G reactants = 97 . 82- (2)(51 . 30) = (- 4 . 78 kJ / mol) µ 1000J kJ ¶ =- 4780 J / mol Δ G =- R T ln K K = e- Δ G / ( R T ) = exp •-- 4780 J / mol (8 . 3145 J / mol · K)(298 K) ‚ = 6 . 88395 006 (part 1 of 1) 10 points What is the form of the equilibrium constant for the process H 2 O( ‘ ) + CO 2 (g) * ) H 2 CO 3 (aq)? 1. K p = [H 2 CO 3 ] [H 2 O][CO 2 ] 2. K c = [H 2 CO 3 ] 2 [H 2 O][CO 2 ] 3. K p = P H 2 CO 3 P 2 H 2 O P 2 CO 2 4. No choice is correct....
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EXAM2SOL - Moore Robert – Exam 2 – Due Mar 8 2007 noon...

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