Metal Potentials Experiment

Perform a first-hand investigation and gather first-hand information to measure the difference in potential of different combinations of metals in an electrolyte solution

  • The difference in potential of different combinations of metals in electrolyte solutions can be measured using the following procedure:
    • Select two metals (Metal A and Metal B) and arrange them and their solutions as shown below:
Experimental setup
    • Observe and record the reading given by the voltmeter.
    • If the voltmeter gives a reading of zero, reverse the terminals, and observe and record the reading again.
    • If the voltmeter gave a positive reading with the initial terminal arrangement, then Metal B is the more easily oxidised metal, while Metal A is the more easily reduced metal.
    • If the voltmeter gave a positive reading after the terminals were reversed, then the nature of the metals is the opposite to the above.
    • The voltage reading corresponds to the difference in potential of the two metals.
    • Repeat the above procedure with different metals in place of Metal B.
    • Use Metal A as a standard (allocate it a potential of zero) to create a table of approximate reduction potentials using the results obtained.
  • In reality, the standard hydrogen electrode is the chosen reference electrode, and is allocated a potential of zero.
  • The standard hydrogen electrode consists of:
    • Platinum foil coated in fine platinum powder dipping into a solution containing 1 mol. L-1 hydrogen ions.
    • Hydrogen gas of 100 kPa pressure and 25°C temperature bubbling over the electrode.
  • When the standard hydrogen half-cell forms one half of a galvanic cell with another half-cell, then the potential difference of the whole cell is a measure of the standard electrode potential of the second half-cell.

Example setup using copper and zinc

Easychem - Metal Potentials Experiment