# 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.