2045Exam1Spring2010FormCodeA

2045Exam1Spring2010FormCodeA - CHM 2045 Exam 1 Gower...

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CHM 2045 Exam 1( Gower, Mitchell) (Form Code A) SP 2010 Instructions: On your scantron sheet enter your name, UF ID number (start on the first space and leave the last space blank), Discussion Section No. and Form Code (see above). This exam consists of 25 multiple choice questions each worth 10.0 points for a total maximum of 250 pts. You may retain your exam sheet (mark your answers on it and the scantron sheet). Turn in only the scantron. Bubbling errors of any kind will count as an incorrect response or result in the loss of points. 1. A 5.82 g coin containing silver is dissolved in nitric acid. When sodium chloride is added to the solution, all of the silver is precipitated as AgCl. The AgCl precipitate weighs 7.20 g. Determine the mass percentage of silver in the coin. (1) 93.1% (2) 89.6% (3) 80.8% (4) 75.3% (5) 23.7% 2. Bromine consists of two naturally-occurring isotopes. If one of these isotopes has a mass of 78.918 amu and is 50.54% abundant, the other isotope has a mass which is closest to (1) 79.82 amu (2) 79.97 amu (3) 80.91 amu (4) 81.93 amu (5) 82.91 amu 3. What is the resulting molarity of Na + ions in a solution prepared by mixing 250 mL of 0.04 M NaCl with 200 mL of 0.02 M Na 2 SO 4 ? (1) 0.03 M (2) 0.04 M (3) 0.01 M (4) 0.02 M (5) 0.05 M 4. A mixture of butene, C 4 H 8 , and butane, C 4 H 10 , is combusted in air to give carbon dioxide and water. Suppose you burn 286.56 g of the mixture and obtain 414.46 g of H 2 O. What is the mass of butene closest to in the mixture? C 4 H 8 (g) + 6 O 2(g) 4 CO 2(g) + 4 H 2 O (g) 2 C 4 H 10 (g) + 13 O 2(g) 8 CO 2(g) + 10 H 2 O (g) 1) 107 g butene 2) 159 g butene 3) 174 g butene 4) 101 g butene 5) 112 g butene 5. The vitamin C, (C 6 H 8 O 6 ) content in a tablet is analyzed by a reaction with bromine and then titration of the hydrobromic acid with standard base: C 6 H 8 O 6 + Br 2 C 6 H 6 O 6 + 2HBr HBr + NaOH NaBr + H 2 O One tablet was dissolved in water and reacted with bromine. The solution was then titrated with 53.20mL of
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This note was uploaded on 11/03/2010 for the course CHM 2046 taught by Professor Veige/martin during the Spring '07 term at University of Florida.

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2045Exam1Spring2010FormCodeA - CHM 2045 Exam 1 Gower...

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