The correct answer is option 2. electrode potentials of both electrodes become equal in magnitude.
To explain why an electrochemical cell stops working after some time, we need to consider the factors that can affect its operation.
An electrochemical cell consists of two electrodes (anode and cathode) immersed in an electrolyte solution. The cell operates based on the difference in electrode potentials between the two electrodes. This potential difference drives the flow of electrons through an external circuit, allowing the cell to produce electrical energy.
(1) One of the electrodes is eaten away: This scenario indicates that one of the electrodes is undergoing corrosion or dissolution, resulting in its degradation. While corrosion can affect the cell's performance, it is not the only reason why an electrochemical cell stops working.
(2) Electrode potentials of both electrodes become equal in magnitude: This situation suggests that the potential difference between the two electrodes decreases until it becomes negligible. When the electrode potentials become equal, there is no driving force for the electron flow, and the cell stops producing electricity.
(3) Electrode potentials of both electrodes go on decreasing: If the electrode potentials continuously decrease over time, the potential difference between the electrodes diminishes. Eventually, the potential difference becomes insufficient to sustain the electron flow, leading to the cell's failure.
(4) Electrode potentials of both the electrodes go on increasing: In this case, the electrode potentials keep rising, leading to an increase in the potential difference between the electrodes. While this can sustain the cell's operation initially, excessively high potentials can cause other issues, such as electrolyte decomposition or electrode degradation, which can ultimately lead to the cell's failure.
Among the given options, (2) electrode potentials of both the electrodes become equal in magnitude is the most accurate explanation for why an electrochemical cell stops working. When the electrode potentials equalize, there is no driving force for the electron flow, resulting in the cell's cessation of operation. |
