H12- Electrochem 1-solutions

H12- Electrochem 1-solutions - madrid (tmm2353) H12:...

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Unformatted text preview: madrid (tmm2353) H12: Electrochem 1 mccord (51625) 1 This print-out should have 21 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Chlorine, bromine, and iodine are good 1. reducing agents. 2. bases. 3. oxidizing agents. correct Explanation: 002 10.0 points When the Ag(s) | AgCl(s) | Cl (aq) electrode acts as a cathode, the reaction is 1. AgCl(s) + e Ag(s) + Cl (aq). cor- rect 2. Ag(s) Ag + (aq) + e . 3. Ag + (aq) + e Ag(s). 4. 2 AgCl(s) + 2 e 2 Ag + (aq) + Cl 2 (g). 5. Ag(s) + Cl (aq) AgCl(s) + e . Explanation: 003 10.0 points Which metal will dissolve in hydrochloric acid? 1. All will dissolve. 2. Fe correct 3. Au 4. Pt 5. Ag Explanation: 004 10.0 points Identify the galvanic cell for the redox re- action between sodium dichromate and mer- cury(I) nitrate in an acidic solution. 1. Hg( ) | Hg 2+ (aq) || H + (aq) , Cr 2 O 2 7 (aq) , Cr 3+ (aq) | Pt(s) 2. Hg( ) | Hg 2+ 2 (aq) || Cr 3+ (aq) | Cr(s) 3. Hg( ) | Hg 2 Cl 2 (s) | Cl (aq) || H + (aq) , Cr 2 O 2 7 (aq) , Cr 3+ (aq) | Pt(s) 4. Pt(s) | Hg 2+ 2 (aq) , Hg 2+ (aq) || H + (aq) , Cr 2 O 2 7 (aq) , Cr 3+ (aq) | Pt(s) correct Explanation: At the cathode, Cr 2 O 2 7 (aq) + 14 H + (aq) + 6 e 2 Cr 3+ (aq) + 7 H 2 O( ) At the anode, Hg 2+ 2 (aq) 2 Hg 2+ + 2 e Equate the e : Cr 2 O 2 7 (aq) + 14 H + (aq) + 2 e 2 Cr 3+ (aq) + 7 H 2 O( ) 3 bracketleftbig Hg 2+ 2 (aq) 2 Hg 2+ + 2 e bracketrightbig Add the balanced half reactions: Cr 2 O 2 7 (aq) + 3 Hg 2+ 2 (aq) + 14 H + (aq) 2 Cr 3+ (aq) + 6 Hg 2+ + 7 H 2 O( ) The cell diagram is Pt(s) | Hg 2+ 2 (aq) , Hg 2+ (aq) || H + (aq) , Cr 2 O 2 7 (aq) , Cr 3+ (aq) | Pt(s) 005 10.0 points Copper is plated on zinc by immersing a piece of zinc into a solution containing copper(II) ions. In the plating reaction, copper(II) ions 1. lose two electrons and are oxidized....
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This note was uploaded on 04/12/2011 for the course CH 302 taught by Professor Mccord during the Spring '11 term at Cornell University (Engineering School).

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H12- Electrochem 1-solutions - madrid (tmm2353) H12:...

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