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An ion dissolved in water subjected to an electric field will move along the field (the etymology of the word ion is ienai "go", from root *ei- "to go", because ions move toward the electrode of opposite charge. ) The force causing movement will stick with the ion.

But, hydronium ions are different in that the proton can jump from one water to another. Much like electrons jumping through a copper crystal in a wire. I wonder how much of the force acting on the hydrogen ion (that is bound to water as hydronium and may or may not jump water molecules when it moves through field) is also transferred to the water molecule(s), vs. how much kind of skips the water molecules since the H+ can jump between molecules.

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Think of the interaction

$$ \require{mhchem} \ce{ H3O+ + H2O -> H2O + H3O+ } $$

as a scattering interaction where the proton may or may not be exchanged. This interaction will have some activation energy. However, the energy requirement is slightly reduced if the positive ion in the final state has its momentum parallel to the electric field, instead of antiparallel.

This isn’t a great description of conductivity in bulk water, where there are lots of collective effects.

For that matter, “electrons jumping” is not a great description of conduction in copper or other metals. A better model there is a lattice of positive ions superimposed with a sea of conduction electrons. At room temperature, the electrons’ wavelengths are large enough that no conduction electron can be properly localized to any single ion; you need many-body quantum mechanics to get much further than that in a quantitative way.

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  • $\begingroup$ I understand the proton can move from one water to another. What I am interested in is if the electrostatic force will act roughly as much on the hydronium molecules (that may or may not be temporary as the hydrogen ion moves in the electric field) as it does on the proton itself. I mean, it seems both might be possible to me. That is why I ask. $\endgroup$
    – BipedalJoe
    Commented Oct 16, 2022 at 18:10
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    $\begingroup$ @BipedalJoe What experimental result do you seek to model? $\endgroup$
    – John Doty
    Commented Oct 17, 2022 at 12:32
  • $\begingroup$ How hydronium acts in electric field, and if the force makes the hydronium(s) move, or if the proton jumping makes it somehow not transfer to the underlying water molecules. $\endgroup$
    – BipedalJoe
    Commented Oct 17, 2022 at 19:17

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