Luigi Galvani, 1791 - an Italian anatomy professor, discovered the flow of current between two metals through a frog's leg. Alessandro Volta - an Italian physics professor, constructed the first continuous source of electric current
Luigi Galvani	Alessandro Volta

Components of a Galvanic Cell

1. Half-cells  - One half of the galvanic cell (e.g. the oxidation half-cell or the reduction half-cell).
2. Anode - Electrode at which oxidation takes place.
3. Cathode - Electrode at which reduction takes place.
4. Salt Bridge - Connecting the two half-cells.
   • The cations, positive ions, flow toward the cathode to replace the cations that are being picked up at the electrode.
   • The anions, negative ions, flow toward the anode to balance the positive charge of the cations that are released from the electrode.
5. A device to detect the amount of current flowing through the cell (in volts).

• A battery is an example of a galvanic cell.

What's Happening in the Galvanic Cell Above??

• The zinc electrode is losing mass as Zn metal is oxidized to Zn²⁺ ions which go into solution.
  • The concentration of the Zn²⁺ solution is increasing.
  • Anions, negative ions (e.g. Cl^-), are flowing from the salt bridge toward the anode to balance the positive charge of the Zn²⁺ ions produced.
• The copper electrode is gaining mass as Cu²⁺ ions in the solution are reduced to Cu metal.
  • The concentration of the Cu²⁺ solution is decreasing.
  • Cations, positive ions (e.g. K⁺), are flowing from the salt bridge toward the cathode to replace the positive charge of the Cu²⁺ ions that consumed.

Remember the following:

RED CAT  &  AN OX

• REDuction occurs at the CAThode

• OXidation occurs at the ANode

Next:  "Electrolytic Cells"