2009 Exam 2 Key

2009 Exam 2 Key - N a m e Section Number Chemistry 1314...

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Unformatted text preview: N a m e Section Number Chemistry 1314 Honors Midterm Exam #2 October 7, 2009 This exam is closed book, notes, papers, etc. You may use a calculator. If you need a physical constant or unit conversion factor that is not provided, please ask. This exam must represent your own work. The final page of the exam contains a great deal of useful information. Rip it off for reference. Scores: 1. / 20 2. a. / 12 b. / 8 3. / 8 4. / 12 5. a. / 8 b. / 12 6. a. / 8 b. / 8 b. / 4 Total: / 100 CHEM 1314 H Midterm Exam #2, 2009 Page 2 1. For each of the following reactions, (i) predict any products (if they arent already given); (ii) complete balanced equations; (iii) identify the reactions as precipitation, acid-base, redox, or none of the above; and (iv) for acid-base reactions identify the acid and the base, for redox reactions write the appropriate oxidation numbers above each atom and identify what is oxidized and what is reduced, and for precipitation reactions identify the precipitate. You do not have to complete the states of matter in the reactions (other than identifying a precipitate). a. MnO 2 + Al b. H 2 S + NaOH c. NiI 2 + (NH 4 ) 2 CO 3 d. SO 2 + NO 3 + H 2 O H + + HSO 4 + NO e. Ca(OH) 2 + HBr f. ZnSO 4 + Cu 2 H 2 O + Na 2 S 2 Acid Base Predicting the products (a,b,c,e,f): 1 point Balancing reaction (a,b,c,d,e): 1 point Reaction type (a,b,c,d,e): 1 point Reaction-specific info (a,b,c,d,e): 1 point 2 NH 4 I + NiCO 3 Precipitation Reaction. Precipitate is NiCO 3 Ox. #s: +4 -2 +5 -2 +1 -2 +1 +1 +6 -2 +2 -2 Redox Reaction. S is oxidized (by 2 electrons); N is reduced (by 3 electrons). 3 3 2 2 2 2 Al 2 O 3 + 3 Mn 4 3 Ox. #s: +4 -2 0 +3 -2 0 Redox Reaction. Al is oxidized (by 3 electrons); Mn is reduced (by 4 electrons). Acid-base reaction. CaBr 2 + 2 H 2 O 2 Base Acid Acid-base reaction. No reaction. Note: The identification of reaction type is implicit in the reaction-specific info (e.g., identifying the acid and the base implies that it is an acid-base reaction). CHEM 1314 H Midterm Exam #2, 2009 Page 3 2. Phosphorus burns in air to give tetraphosphorous decaoxide: ( ) ( ) ( ) mol kJ H s O P g O s P / 062 , 3 5 4 1 10 4 2 = + The product of this reaction combines with water to give phosphoric acid: ( ) ( ) ( ) mol kJ H l PO H l O H s O P / 2 . 257 4 6 2 4 3 2 10 4 = + a. Using these equations and the thermochemical data in the table on the last page, calculate the enthalpy of formation of phosphoric acid....
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2009 Exam 2 Key - N a m e Section Number Chemistry 1314...

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