Exam2Solutions - Johnson, Chelsea Exam 2 Due: Mar 7 2007,...

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Unformatted text preview: Johnson, Chelsea Exam 2 Due: Mar 7 2007, noon Inst: Walker 1 This print-out should have 16 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. Read all of the options before choosing one. There may be cases in which more than one response appears to be true. PICK THE RE- SPONSE THAT BEST answers the question asked. NOTE: Do not convert given atm to torr. Solve using atm, just as we did on homework. 001 (part 1 of 1) 13 points Which acid is weaker? 1. HNO 3 2. HNO 2 correct 3. They have the same strength. Explanation: HNO 3 is he stronger oxoacid; there is one more O atom attached to the N atom in HNO 3 than in HNO 2 . This makes the H O bond more polar (and thus more easily broken) in HNO 3 than in HNO 2 . 002 (part 1 of 1) 13 points Which of the following salts produces a neu- tral solution when it is dissolved in water? 1. LiF 2. KCN 3. KCH 3 CO 2 4. NaClO 5. NaBr correct Explanation: 003 (part 1 of 1) 13 points How much acetic acid ( K a = 1 . 8 10- 5 ) must be used to prepare a liter of solution having a pH of 2.75? 1. 9.88 moles 2. 5.69 moles 3. 0.178 moles correct 4. 0.435 moles 5. 0.0101 moles Explanation: pH =- log[H + ] = 2 . 75 so [H + ] = log- 1 (- 2 . 75) = 1 . 778 10- 3 mol HA * ) H + + A- Subsitute [H + ] = [A- ] = 1 . 778 10- 3 into the equation for K a : K a = [H + ][A- ] [HA] [HA] = [H + ][A- ] K a = ( 1 . 778 10- 3 ) 2 1 . 8 10- 5 . 178 mol 004 (part 1 of 1) 11 points The state of dynamic balance that exists when the forward and reverse processes of a re- versible reaction are occuring simultaneously at the same rate is called 1. equilibrium constant. 2. chemical equilibrium. correct 3. heterogeneous equilibrium....
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This note was uploaded on 09/28/2009 for the course GE 206E taught by Professor staff during the Spring '09 term at University of Texas at Austin.

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Exam2Solutions - Johnson, Chelsea Exam 2 Due: Mar 7 2007,...

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