Exam2AKey - CHEM 142D Second Midterm 2009 November 23 You...

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CHEM 142D Second Midterm 2009 November 23 Page 1 You must mark version A on side 1 of the Answer Sheet. Chemistry 142D Multiple Choice Second Exam (a) Before starting, make sure your exam has 7 pages, including the periodic table. (b) To receive credit you must be sitting in your assigned seat or discuss a move with your TA. (b) Fill in your name, section, and student number on Side 1 of the Answer Sheet . (c) To receive credit, you must mark Test Version A on Side 1 of the answer sheet. (d) When you are done with the exam, hand the Answer Sheet to a TA. (e) The exam is over at 6:20 PM. No answer sheet will be accepted after 6:20 PM. (e) Our final exam is scheduled for MONDAY, DECEMBER 14 at 6:30 PM in this room. (f) Avogadro’s number, Gas Constant and pressure units: 23 6.022 10 0.08206 11 1 7 6 0 1 0 1 . 31 4 . 7 A Atm NR mol K torr mm Hg Atm mm Hg kPa psi ± ² ± A
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CHEM 142D Second Midterm 2009 November 23 Page 2 You must mark version A on side 1 of the Answer Sheet. 1. (6 points) A solution is prepared by dissolving 25 grams of Ammonium Sulfate, , a strong electrolyte, in enough water to make 100 ml of stock solution. Then 10 ml of this solution are diluted to 50 ml, with water. What is the molar concentration of the ammonium ion, ±² ± 44 2 NH SO aq ² ± ² 4 NH aq ³ , in the final solution? ± ² 0.424 2.12 0.847 4.24 0.757 a b c d e 2. (6 points) What volume of 0.1 M Na 3 PO 4 is required to precipitate all of the lead(II) ions as from 150.0 ml of a 0.25 M solution of ? ± 34 2 Pb PO s ² l l l l l 3 2 Pb NO 250 125 563. 56. 375 am bm cm dm em 3. (7 points) Balance the following reaction using the smallest integers possible and select the correct stoichiometric coefficient for the water.
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Exam2AKey - CHEM 142D Second Midterm 2009 November 23 You...

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