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Concentration Cell

Chemicals and Solutions

  • 1 Molar Copper Sulfate solution
  • 10 millimolar Copper Sulfate solution
  • Two copper strips, each in a metal holder

Materials

  • Two 400 mL beakers
  • Salt bridge
  • Digital Voltmeter
  • Alligator clips

Procedure

Fill one beaker half full with 1M copper sulfate solution and place one of the copper strips in the solution. Fill the other beaker half full with a 10 millimolar solution of copper sulfate and place another copper strip in this solution. Connect the copper strips to the digital voltmeter and then complete the circuit by inserting a salt bridge.

Discussion

The potential of a concentration cell is given by the Nerst equation.

The 1 millimolar compartment is the anode:

\( \ce{ Cu_{(s)} -> Cu2+_{(aq)} + 2e- } \)

and the 1 M compartment is the cathode

\( \ce{ Cu2+_{(aq)} + 2e- -> Cu_{(s)} } \)

For a concentration cell Eo is zero because both compartments are identical. For the copper concentration cell, the number of electrons transferred per copper atom is 2, so n=2.

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