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प्रश्न
Daniel cell is an electrochemical cell, which converts chemical energy into electrical energy. With the help of the internet find what electrodes and electrolytes are used in the Daniel cell. Prepare a presentation on its working. Figure out what could be the possible reactions taking place at the cathode and anode.
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उत्तर
A Daniell cell is an electrochemical (galvanic) cell that converts chemical energy into electrical energy. It consists of two half-cells: a zinc electrode in zinc sulphate solution and a copper electrode in copper sulphate solution. The two solutions are connected by a salt bridge, while the electrodes are connected by an external wire.
1. Electrodes and Electrolytes:
| Component | Used in Daniell Cell |
|---|---|
| Anode (negative electrode) | Zinc rod (Zn) |
| Cathode (positive electrode) | Copper rod (Cu) |
| Electrolyte in anode half-cell | Zinc sulphate solution (ZnSO4) |
| Electrolyte in cathode half-cell | Copper sulphate solution (CuSO4) |
| Salt bridge | Usually contains an inert electrolyte such as KCl or NH4NO3 |
The zinc and copper electrodes are immersed in their respective electrolyte solutions.
2. Working of the Daniell Cell:
At the zinc electrode (anode), zinc loses electrons and enters the solution as zinc ions:
\[\ce{Zn_{(s)} -> Zn^{2+}_{ (aq)} + 2e-}\]
This is an oxidation reaction.
The released electrons flow through the external wire from the zinc electrode to the copper electrode.
At the copper electrode (cathode), copper ions gain these electrons and are deposited as copper:
\[\ce{Cu^{2+}_{ (aq)} + 2e- -> Cu_{(s)}}\]
This is a reduction reaction.
The salt bridge allows ions to move between the two half-cells and helps maintain electrical neutrality.
3. Overall Reaction:
Adding the two half-reactions:
\[\ce{Zn + Cu^{2+} -> Zn^{2+} + Cu}\]
or, using the sulphate ions:
\[\ce{Zn + CuSO4 -> ZnSO4 + Cu}\]
Thus, the spontaneous redox reaction produces electrical energy.
