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.