The positive electrode is zinc electrode: O? + 4e？ + 2H？ O = 4OH？
Total electrode reaction equation: 2Fe+O? +2H？ O = 2Fe + 4OH？
When iron and zinc electrodes are immersed together in sodium chloride solution (electrolyte), because iron is more active than zinc, it is easy to lose electrons. Iron is oxidized into bivalent iron and enters the solution, and electrons flow from iron sheet to zinc sheet through wires. The hydrogen ions in the solution get electrons from the zinc sheet and are reduced to hydroxide.
Extended data
1. If the ammeter pointer connected in series with wires does not deflect or deflects instantly after connection, it is a fault phenomenon. It is also a failure phenomenon when no gas is generated at the contact between the solution and an electrode such as a copper electrode.
If it is difficult to find the pure zinc sheet, soak the crude zinc in saturated mercuric chloride solution, take it out with tweezers and wash it before use. Avoid touching the solution with your hands, and be sure to wash your hands with soap after the experiment.
2. Sodium chloride is necessary for many biological reactions. For example, in molecular biology experiments, various solution formulations contain sodium chloride, and most bacterial culture media contain sodium chloride. At the same time, it is also the raw material for the production of soda ash by ammonia-alkali method.
Baidu encyclopedia-sodium chloride
Baidu encyclopedia-copper-zinc primary battery