Electrode Potential Lecture Notes

Introduction to Cells

• Cell: A device converting physical or chemical energy into electrical energy.
• Components of a Cell:
  • Made up of two electrodes.
  • Each electrode is known as a half-cell.

Examples of Half-Cells

• Hydrogen half-cell
• Zinc half-cell
• Copper half-cell
• Iron half-cell
• Chlorine half-cell

Electrode Potential

• Definition: The potential difference between two half-cells.
• Standard Electrode: Hydrogen electrode used as a standard (0.00 V).
• Comparison: Other electrodes are compared to the hydrogen electrode to determine their potential.

Electrode Potential Example

• Hydrogen Electrode:
  • Acts as a reference electrode.
  • Composed of 1 molar H+ from HCl and hydrogen gas supplied into the solution.
  • Platinum wire is used to conduct electricity.
• Zinc Electrode:
  • Contains 1 molar Zn2+ from ZnSO4.
  • A zinc rod is immersed for conduction.
  • No platinum wire needed as zinc itself conducts electricity.
• Measurement:
  • A galvanometer measures the potential difference.
  • Potential Difference:
    • Hydrogen: 0.00 V
    • Zinc: -0.76 V (reduction potential)
    • Oxidation potential would be +0.76 V (Zn → Zn2+).

Electrochemical Series

• Lists metals and their electrode potentials:
  1. Cerium: +1.61 V
  2. Gold: +1.50 V
  3. Chlorine: +1.36 V
  4. Copper: +0.34 V
  5. Hydrogen: 0.00 V
  6. Iron: -0.44 V
  7. Zinc: -0.76 V
  8. Aluminum: -1.66 V
  9. Sodium: -1.71 V
  10. Lithium: -3.04 V

Conclusion

• The electrode potential is a crucial concept in electrochemistry, helping to understand and order metals by their ability to gain/lose electrons relative to hydrogen.