Conditions from which a Galvanic Cell is Produced

9.1 Practical Skills: Practical Skills

Setting up a galvanic cell:

Method:

  1. Fill two beakers with 1 molar solutions of ZnSO4 and CuSO4 (Zinc and Copper Sulfate respectively).
  2. Add a salt bridge to (PRESERVE ELECTRICAL NEUTRALITY)1
  3. Apply a gentle pressure with sandpaper or an abrasive in order to clean the surface of the metal. (i love brasso)
  4. Complete the circuit with firm crocodile clip contacts and attach the cells to a voltmeter to measure the voltage produced.

Expected Results:

There are a number of conditions which must be met in order for a galvanic cell to function.

  • There must be an anode and cathode, each within their respective electrolytic solutions and physically separated.
  • A conducting circuit must connect the two half-cells to provide the only path by which electrons can flow.
  • A salt bridge must exist. The purpose of a salt bridge is to maintain electrical neutrality as ions migrate from half-cell to half-cell in order to maintain a balance in charges. If a charge imbalance builds up (as would occur if there is no salt bridge present), the cell would cease to function, as ions will accumulate in both electrolytes until the potential difference due to the ions is exactly opposite to the potential difference from the reaction. Thus the flow of electrons would be negated, and there would be no current.

Important: Salt bridge components must not be able to form precipitates with the electrolytes or it will not perform as a preserver of electrical neutrality.