| Aim | To study the variation of cell potential in Zn/Zn2+||Cu2+/Cu with a change in concentration of electrolytes (CuSO4 or ZnSO4) at room temperature. |
| Apparatus Required | Zinc metal strip Copper metal strip Copper sulfate solution Zinc sulfate solution Two beakers Salt bridge (KCl soaked agar-agar) Multimeter/voltmeter Wires |
| Theory | Electrochemistry deals with the relationship between electrical energy and chemical reactions. A galvanic cell is a device that converts chemical energy into electrical energy. The cell potential is the potential difference between the electrodes of a galvanic cell. In this experiment, the variation of cell potential in Zn/Zn2+||Cu2+/Cu with a change in concentration of electrolytes (CuSO4 or ZnSO4) will be studied. |
| Procedure | Prepare two half-cells: a Zinc (Zn) electrode in a beaker containing 0.1M ZnSO4 solution, and a Copper (Cu) electrode in a beaker containing 0.1M CuSO4 solution. Connect the two half-cells with a salt bridge or porous cup containing a 1M KCl solution. Measure the initial voltage of the cell using a voltmeter. Add 1 mL of 0.1M CuSO4 solution to the Cu half-cell and measure the voltage of the cell after the solution has mixed. Record the voltage and repeat step 4, adding another 1 mL of CuSO4 solution. Repeat step 4 and 5 until you reach a concentration of 1.0M CuSO4. Repeat steps 4 to 6 with the ZnSO4 solution, starting with 1 mL of 0.1M ZnSO4 solution and increasing it until a concentration of 1.0M ZnSO4. |
| Observation and Result | Observation: As the concentration of CuSO4 solution is increased, the voltage of the cell gradually decreases from its initial value. Conversely, as the concentration of ZnSO4 solution is increased, the voltage of the cell gradually increases from its initial value. Result: The change in cell potential with concentration change can be plotted to obtain a graph of voltage versus concentration. The graph will show that the cell potential decreases logarithmically with increasing concentration of CuSO4 solution, and increases logarithmically with increasing concentration of ZnSO4 solution. This observation can be explained by the Nernst equation, which shows that the potential of an electrochemical cell is dependent on the concentration of the electrolytes. |