During electrolysis, the anode is acidic – why don’t hydrogen ions move toward the cathode?
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Was it simply the migration of sodium ions from the anode to the cathode that was last edited in this post by sunjl1981 on 2013-1-6 at 22:57? I really don’t understand. # + + .
Reply to 1# hiwxj: The so-called ion exchange membrane here refers to the sodium ion exchange membrane. To put it simply, the sodium ions in the anode chamber do not pass through like they would through a sieve; instead, they exchange places with the sodium ions in the sulfonic acid layer and carboxylic acid layer under the influence of an electric field, which allows them to enter the cathode chamber. Hydrogen ions and oxygen ions, on the other hand, are what enable water molecules to move from the anode chamber to the cathode chamber, using a different pathway. The forum contains an electronic version of the book \"Production Technology of Caustic Soda using Ion-Exchange Membranes.\" You can search for it and download it to read; it is written in an easy-to-understand manner, with both illustrations and text. I can’t express myself accurately while typing here; I’m sorry.
As I understand it, sodium ions are exchanged or migrate to the cathode in a hydrated form, but theoretically hydrogen ions can also migrate as hydrated ions, and theoretically their direction of migration is exactly the same as that of the electric field (obviously, which is why it’s called migration under the influence of an electric field). But in fact, the vast majority of those that migrate to the cathode are indeed sodium ions. So does this mean that the ion membrane is selective to sodium ions, or is it that the concentration of hydrogen ions in the anode is actually very low (0.001 mol/L)? So it can’t compete with sodium ions (4-5 mol/L)? I think an explanation of too low a concentration is more reasonable. After all, since hydrogen ions have a small volume and low mass, they are subject to a greater force from the electric field relative to other particles. However, due to the extremely low concentration, the vast majority of those that can migrate to the cathode are sodium ions. Hehe. It suddenly seemed like a very thorough explanation.
Reply to 3# hiwxj: Haha, I don’t agree with your view. .
Reply to 3# hiwxj: http://bbs.hcbbs.com/thread-121207-1-1.html There might be materials and books you like on that link; go take a look.