Cell potentials and Reduction potentials

1. Cell potentials and Reduction potentials

2. Answers 1 - 5 1. The difference is “ ° ” - indicating 25°C and 1 M concentrations (1) 2. Voltages can be increased by arranging cells in series (1) (or changing concentrations) 3. “A measure of the tendency of a given half-reaction to occur as a reduction” (1) 4. The half-cell with the greater reduction potential will gain electrons (1) 5. The Cu half-cell has the greater reduction potential (1), since it is gaining electrons (1) /6

3. Answers 6 - 10 6. The Fe half-cell has the greater reduction potential (1) 7. E°cell = E°reduced - E°oxidized (1) (E°cell = standard reduction potential of substance reduced - standard reduction potential of substance oxidized) 8. 0.62 V (1) 9. There is no way to measure the standard reduction potential of an isolated half-cell (1) A reference/standard electrode is chosen (1) 10. Cu has the greatest reduction potential (1) /6

4. Answers 11 - 14 11. 0.00 V is the reduction potential for the hydrogen electrode (1) 0.00 V is arbitrarily set; it’s 0 by definition (1) 12. It has a lower reduction potential than the hydrogen electrode (1) 13. Either oxidation OR reduction can occur depending upon what the half-cell is coupled with (1) 14. E°cell = E°reduced - E°oxidized E°cell = E°Fe2+ – E°Mg2+ 1.96 V = -0.41 V – E°Mg2+ (1) E°Mg2+ = -0.41 V – 1.96 V = -2.37 V /5

5. Answers 15 - 18 15. 5.92 V (1) by a F2 - Li cell (1) 16. a) 1.42 V - -0.25 V = 1.67 V (1) b) 0.80 V - 0.34 V = 0.46 V (1) c) -1.66 V - -2.37 V = 0.71 V (1) d) 0.34 - - 0.44 V = 0.78 V or 0.77 V - 0.34 V = 0.43 V (1) 17. Yes (1) because the larger reduction potential will be reduced, the smaller will be oxidized (E°cell = E°reduced - E°oxidized) 18. Yes (1) because you are subtracting a smaller (or more negative) number from a larger number /8, /25 For more lessons, visit www.chalkbored.com