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Unformatted text preview: goins (jmg3964) – Post-lab 3 – lyon – (51215) 1 This print-out should have 18 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points What is/are the products of the decompo- sition reaction in the reaction series of the copper cycle in this experiment? 1. Cu(NO 3 ) 2 (aq) + NO 2 (g) 2. CuSO 4 (aq) + H 2 O(l) 3. CuO(s) + H 2 O(g) correct 4. Cu(s) Explanation: Decomposition reactions occur when a sin- gle reactant produces more than one product (usually by heating the reactant). When solid copper(II) hydroxide is heated, it decomposes into copper(II) oxide and water vapor. Cu(OH) 2 (s) + heat → CuO(s) + H 2 O(g) 002 (part 1 of 2) 10.0 points Which of the following reactions (reactants only) in the copper cycle is a redox reaction? (Note that the reactants are not balanced in the equations below.) 1. Cu(OH) 2 (aq) + heat → 2. CuSO 4 (aq) + Al(s) → correct 3. Cu(NO 3 ) 2 (aq) + NaOH(aq) → 4. CuO(s) + H 2 SO 4 (aq) → Explanation: 003 (part 2 of 2) 10.0 points Which reactant in the redox reaction above is the reducing agent ? 1. Cu(OH) 2 2. Cu(NO 3 ) 2 3. CuSO 4 4. CuO (s) 5. Al correct 6. NaOH 7. H 2 SO 4 Explanation: When copper sulfate solution is reacted with aluminum metal, copper metal and alu- minum sulfate solution are produced. This is a redox reaction as indicated by the change of oxidation states of copper and aluminum once the reaction is complete. Remember that metals in their natural state have a zero oxidation number. The unbalanced half reac- tions are: Cu 2+ (aq) + 2e- → Cu (s) reduction (oxi- dizing agent) Al (aq) → Al 3+ + 3e- oxidation (reducing agent) 004 10.0 points When copper metal is reacted with nitric acid, the copper metal is (reduced / oxidized) and the number of electrons transferred in the reaction is/are (one or two or three)....
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This note was uploaded on 10/25/2010 for the course CH 204 taught by Professor Leytner during the Fall '08 term at University of Texas.
- Fall '08