The determination of the anode and cathode from the electrode potential involves considering the sign of the electrode potential values.
In electrochemistry, the electrode potential (also known as the reduction potential or half-cell potential) is a measure of the tendency of an electrode to gain or lose electrons in a redox reaction. It is typically measured against a reference electrode, such as the standard hydrogen electrode (SHE).
The sign convention for electrode potentials is as follows:
Positive electrode potential: A positive electrode potential indicates that the electrode is more likely to undergo reduction (gain electrons) compared to the reference electrode. In this case, the electrode is considered the cathode.
Negative electrode potential: A negative electrode potential indicates that the electrode is less likely to undergo reduction and is more likely to undergo oxidation (lose electrons) compared to the reference electrode. In this case, the electrode is considered the anode.
To determine the anode and cathode in a given electrochemical cell, you compare the electrode potentials of the individual electrodes against each other. The electrode with the more positive potential (relative to the reference electrode) is the cathode, and the electrode with the more negative potential is the anode.
It's important to note that the determination of the anode and cathode depends on the reference chosen and the convention used. Different references or conventions might result in the reversal of anode and cathode designations.