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Understanding Redox Reactions and Electrochemical Cells in Chemistry

This comprehensive guide covers the principles of redox reactions, electrolytic and galvanic cells, and electron flow in metallic and ionic conduction. It includes detailed steps to determine the redox reactions and voltage in electrochemical cells, identifying half-reactions from standard redox tables, and balancing electron transfers. Additionally, the guide explains key concepts like electrodes, salt bridges, and the significance of spontaneity in reactions. Engage in practice problems to solidify your understanding and enhance your skills in electrochemistry.

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Understanding Redox Reactions and Electrochemical Cells in Chemistry

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  1. Balance Redox Rxns: • Fe(OH)3 + • [Cr(OH)4]-1 • Fe(OH)2 + CrO4-2

  2. AP CHM HW • Read: Chapter 18

  3. Review the Multiple-Choice Section of the Midterm.

  4. Electro-chemistry

  5. Metallic Conduction • The flow of electrons through a metal

  6. Ionic Conduction • The movement of ions (electrolytes) through a solution • Electrolytic Conduct.

  7. Electrode • The surface or point in which oxidation or reduction takes place

  8. Anode • The electrode where oxidation takes place • An Ox (-)

  9. Cathode • The electrode where reduction takes place • Red Cat (+)

  10. Voltaic or Galvanic Cell • Electrochemical Cell in which:

  11. a spontaneous oxidation-reduction reaction produces electrical energy

  12. Half-Cell • A cell where only oxidation or only reduction takes place

  13. An electrochemical cell must have two half-cells connected by a salt bridge

  14. A half-cell will not work by itself • Both half-cells are required

  15. Salt Bridge • ) Allows electrical contact between the two half-cells

  16. ) Prevents mixing of the two half-cell solutions

  17. ) Allows ions to flow maintaining electrical neutrality

  18. Determining the Redox Rxn & Voltage of an Electrochemical Cell

  19. Identify all molecules & ions (reactants) that exist in the electrolytic cell

  20. ) Determine all possible half-reactions that could occur in the system

  21. ) Look up each half-rxn from the Std. Redox Tables

  22. ) Record each half-rxn & its standard voltage

  23. ) Save the oxidation half-rxn that has the highest voltage

  24. ) Save the reduction half-rxn that has the highest voltage

  25. ) Balance the electrons between the two half-rxns

  26. ) Add the two half-rxns to obtain the full electrochemical reaction

  27. ) Add the voltage of each half-rxn to obtain the std. voltage required

  28. Determine Eo Zn(s) + 2 Ag+1(aq) 2 Ag(s) + Zn+2(aq)

  29. AP CHM HW • Read: Chapter 18 • Problems: 7 & 15a • Page: 526

  30. REDOX Shorthand • Zn|Zn+2||Ag+1|Ag ox red • Zn||Zn|Zn+2||Ag+1|Ag||Pt an ox red cat

  31. Drill: Determine Shorthand Rxn & voltage when Cu+1 is reacts with solid potassium

  32. Voltaic Cell Problems

  33. Determine all when a cell with a Cu electrode in CuCl2(aq) is connected to a cell with a Zn electrode in ZnBr2(aq)

  34. Determine all when a cell with a Fe electrode in FeCl3(aq) is connected to a cell with a Mn electrode in MnCl2(aq)

  35. Determine all when a cell with a Mg electrode in MgCl2(aq) is connected to a cell with a Au electrode in AuCl3(aq)

  36. Drill: What is the best reducing agent on the chart?

  37. Electrolysis • Using electricity to force an, oh fooey, non-spontaneous electrochemical rxn

  38. Electrolytic Cell • Chemical cell where electrolysis is being performed

  39. How to determine the Redox Rxn & voltage of an Electrolytic Cell

  40. Identify all molecules & ions (reactants) that exist in the electrolytic cell

  41. ) Determine all possible half-reactions that could occur in the system

  42. ) Look up each half-rxn from the Std. Redox Tables

  43. ) Record each half-rxn & its standard voltage

  44. ) Save the oxidation half-rxn that has the highest voltage

  45. ) Save the reduction half-rxn that has the highest voltage

  46. ) Balance the electrons between the two half-rxns

  47. ) Add the two half-rxns to obtain the full electrochemical reaction

  48. ) Add the voltage of each half-rxn to obtain the std. voltage required

  49. Determine the rxn that takes place when 1.5 V is passed through two Pt electrodes in a solution containing MgI2(aq) & ZnCl2(aq)

  50. AP CHM HW • Read: Chapter 18 • Problems: 23 • Page: 527

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