Electrode Whewell at Faraday's request). The anode is now defined as the electrode at which electrons leave the cell and oxidation occurs (indicated by a minus symbol, "−"), and the cathode as the electrode at which electrons enter the cell and reduction occurs (indicated by a plus symbol, "+"). Each electrode may become either the anode or the cathode depending on the direction of current through the cell. A bipolar electrode is an electrode that functions as the anode of one cell and the cathode of another cell. A primary cell is a special type of electrochemical cell in which the
Standard hydrogen electrode from the previous one it was given the name 'Standard Hydrogen Electrode'. In summary, The choice of platinum for the hydrogen electrode is due to several factors: The surface of platinum is platinized (i.e., covered with platinum black) to: Other metals can be used for building electrodes with a similar function such as the palladium-hydrogen electrode. Because of the high adsorption activity of the platinized platinum electrode, it's very important to protect electrode surface and solution from the presence of organic substances as well as from atmospheric oxygen. Inorganic ions that can reduce to a lower valency state at the