To study the variation of cell potential in Zn/Zn²+ ||Cu²+/Cu cell with change in concentration of electrolytes (CuSO₄, and ZnSO₂) at room temperature.
Requirements:
Two beakers, connecting wires, copper and Zine plate, sandpaper, voltmeter, U-shaped tube, etc.
Chemical Required
Zinc Sulphate (1 M), Copper Sulphate (1 M), and KCI.
Theory:
The complete redox reaction in Daniel cell can be represented as:
Zn(s) → Zn2+(aq) + 2e−
Cu2+(aq) + 2e− → Cu(s)
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Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s) (Overall cell reactions)
The emf of the cell can be calculated using the Nernst equation as:
As in clear the emf of a cell depends on the concentration of ions.
Procedure:
1.Take two beakers and fill one with 100ml of IM CuSO₄ and other with 100ml of IM ZnSO4
2. Clean a copper strip and dip it into CuSO₄ solution.
3. Similarly dip a Zine strip into ZnSO₄ solution.
4. Place the two beakers side by side and hang a U-tube (salt bridge) containing a paste of KCl and agar agar.
5. Connect both the metal strips through a voltmeter. (Cu strip with +ve terminal and Zn strip with -ve terminal).
6. Note the reading in the voltmeter.
7. Keeping the concentration of ZnSO₄, fixed (IM), and taking different concentrated of CuSO₄, repeat the experiment, and record the observations.
Observations Table
S.No. | Concentration of ZnSO₄ solution | Concentration of CuSO₄ solution | Ecell |
1. |
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2. |
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3. |
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4. |
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Precautions:-
The strip of Zn and Cu should be properly cleaned with the help of sandpaper. Note the reading of the voltmeter only when the pointer becomes stable.
Result
The cell potential decreases with decrease in concentration of CuSO4.
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