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Instead of covering the ends of the salt bridge in an electrochemical cell with a membrane, one could also plug them on both sides with a conductive non-porous material, for example gold, which doesn't go into solution. Would the accumulation of the ions at the plugs and their electrostatic force field be enough to keep the cell running?

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    $\begingroup$ In doing so, you will effectively split your electrochemical cell in two independent cells, each having gold as one of their electrodes. Then you may apply the common rules to see if these cells will work. $\endgroup$ – Ivan Neretin Mar 31 '19 at 8:32
  • $\begingroup$ I think the gold plugs would not act as electrodes - gold ions would not go into solution, and there is no wire between the gold and the other electrode. The plugs do not necessarily have to be a metal - I want them to be non porous and able to let the electric field through that the accumulating charges have. I think a closed glass tube would also work. $\endgroup$ – yippy_yay Mar 31 '19 at 9:02
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It is a very good thought experiment as to why we don't cap the salt bridge ends with gold plugs. By capping, you are essentially providing an interface which can source and sink for electrons in the cells, thus each end will act as an electrode in the cell. One end of the salt bridge will act as a cathode and one end will act as an anode (strange as it may sound!)

As to your comment above "I want them to be non porous and able to let the electric field through that the accumulating charges have. I think a closed glass tube would also work". No a close tube will not work. You need the ions or electrons to move in order to observe current flow. A closed glass tube will have an infinite resistance and hence no current can flow!

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  • $\begingroup$ The ions inside of the closed glass salt bridge could move - and would polarize the solution inside the closed glass salt bridge by opposite charged ions accumulating in opposite ends.The opposite charges in the solution on the other side of the glass would mirror the charges and push up against the salt bridge. The resulting electrostatic field would be zero, I suppose. And that's what a salt bridge should accomplish. I am not sure I am right, so that is why I ask the question. $\endgroup$ – yippy_yay Apr 2 '19 at 20:20
  • $\begingroup$ I upvoted your answer sometime ago. Of course, you are correct for the glass rod. I just did a very rough calculation assuming a "closed glass salt bridge" with electrolyte filling, etc., resulting in about 0.25 pF equivalent capacitance. Even if charged to 1 V, this is only about 1.5 million electrons worth of charge. The charging would take place very quickly and it would be a fairly finicky to measure. So, case closed as far as I can see! $\endgroup$ – Ed V Apr 25 at 23:16
  • $\begingroup$ Could you add your rough calculations as a separate answer? I think it be very useful. Thanks. $\endgroup$ – M. Farooq Apr 26 at 1:53

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