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Unformatted text preview: 1 Worked Solutions for Web Quiz #6 1. The standard free energies of formation of several aqueous species are: H + ( aq ) 0 kJ/mol H 2 O( l ) -237 kJ/mol CH 3 OH( aq ) -163 kJ/mol HCOOH( aq ) -351 kJ/mol e- 0 kJ/mol What is the standard reduction potential of methanoic acid in aqueous solution (i.e., for HCOOH + 4H + + 4e- CH 3 OH + H 2 O)? (2 sig figs) 2. A common car battery consists of six identical cells each of which carries out the reaction Pb + PbO 2 + 2HSO 4- + 2H + 2PbSO 4 + 2H 2 O Suppose that in starting a car on a cold morning a current of 125 amperes is drawn for 15.0 seconds from a cell of the type described above. How many grams of Pb would be consumed? (The atomic weight of Pb is 207.19.) A. 8.05 B. 2.01 C. 0.018 D. 0.036 E. 4.02 2 3. A fuel cell designed to react grain alcohol with oxygen has the following net reaction: C 2 H 5 OH( l ) + 3O 2 ( g ) 2CO 2 ( g ) + 3H 2 O( l ) The maximum work one mole of alcohol can yield by this process is1320 kJ. What is the theoretical maximum voltage this cell can achieve? A. 0.760 V B. 1.14 V C. 2.01 V D. 2.28 V E. 13.7 V 4. Consider the following reduction potentials: Cu 2+ + 2e- Cu E ° = +0.34 V Pb 2+ + 2e- Pb E ° = -0.13 V For a galvanic cell employing the Cu, Cu 2+ and Pb, Pb 2+ couples, calculate the maximum amount of work that would accompany the reaction of one mole of lead under standard conditions....
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This note was uploaded on 10/20/2009 for the course CHEM 105BLG taught by Professor Parr during the Spring '08 term at USC.
- Spring '08