I understand that in electrolysis of water, the water around cathod is splited in the way of 4H2O + 4e => 2 Hydrogen + 4 OH- . And the hydroxide will move to the anode due to electric field in the water. However, if there is a a group of OH- moving in the water, they should give momentum to the neutral water molecules in their way. Did this actually happen? If not, how did the neutral water molecules reacted to the moving OH-?


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Water is not hyper fluid, it has resistance too. If you notice a little bit, water is kind of "sticky" on a glass, plus there's brownian motion. Thus I doubt you would notice any activity at all without some very fancy tool. Also, you still have momentum conservation.

However, it's possible that, if you could find a way to "color mark" the water, like isotropic or molecular, it's possible to see the influence by eye, because, theoretically, with the presence of electric field, the ion should travel faster than the diffusion.

  • $\begingroup$ @SolarMike Yes, Thanks. Adjusted. $\endgroup$ Commented Jul 28, 2019 at 5:36
  • $\begingroup$ So if the electrolysis happened in a tube with the eletrodes on both end of the tube and the cathode can turn (hypothetically) the entire cross-section area of water into OH-, then this circular volume of OH- could push the neutral water into a visible motion (similar to a thrust?) $\endgroup$
    – user39178
    Commented Jul 28, 2019 at 11:54
  • $\begingroup$ However, if ions could just squeezed itself from from cathode to the anode, why could ionocraft fly by using the ions to push neutral air to create ion wind? $\endgroup$
    – user39178
    Commented Jul 29, 2019 at 11:21

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