An electrochemical cell stops working after sometime because

Options

A. one of the electrodes is eaten away
B. electrode potentials of both the electrodes go on increasing
C. electrode potential of both the electrodes go on decreasing
D. electrode potentials of the two electrodes becomes equal in magnitude

Answer

To solve the question "An electrochemical cell stops working after some time because:", we need to analyze the functioning of an electrochemical cell and the reasons behind its eventual failure.

### Step-by-Step Solution:

1. **Understanding Electrochemical Cells**:
- An electrochemical cell consists of two electrodes: an anode and a cathode. At the anode, oxidation occurs (loss of electrons), and at the cathode, reduction occurs (gain of electrons).

2. **Electron Transfer**:
- In a typical electrochemical cell, electrons are transferred from the anode to the cathode. For example, in a zinc-copper cell, zinc (Zn) oxidizes to Zn²⁺ by releasing electrons, while Cu²⁺ at the cathode gains electrons to form copper (Cu).

3. **Electrode Potentials**:
- Each electrode has a specific electrode potential (E°). The potential difference between the anode and cathode drives the flow of electrons. Over time, as the reaction proceeds, the concentrations of the reactants and products change, affecting the electrode potentials.

4. **Equilibrium State**:
- Eventually, the system reaches a point where the electrode potentials become equal in magnitude. This means that the driving force for the electron transfer diminishes, leading to a halt in the electrochemical reaction.

5. **Conclusion**:
- Therefore, the electrochemical cell stops working because the electrode potentials of the two electrodes become equal in magnitude, resulting in no further electron transfer.

### Final Answer:
The electrochemical cell stops working after some time because the electrode potentials of the two electrodes become equal in magnitude.

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