[Shah]

Can electrons flow through the salt bridge in a galvanic cell?

if we didn't connect the two electrodes with a wire, could the reaction occur by flowing of electrons through the salt bridge.

in case there was a porous surface instead of the the salt bridge, Could the electrons migrate through the porous disk instead of flowing in the wire that connects the two electrodes?

[Nobby]

In the salt bridge is wet potassium chloride. And this is of course conductive.

[rabolisk]

Yes, they could. However, the reason for the wire is to use the cell (battery) to derive electrical energy from the reaction, and do work with it. Without a wire, you would get a reaction and heat loss, but no useful work.

[DevaDevil]

In the salt bridge is wet potassium chloride.

salt bridges can consist of many different chemicals. wet KCl is often convenient as it doesn't leak out. In my salt bridges I use the same electrolyte I have in my cell, usually dilute perchloric acid.

What you are perfectly correct about is that salt bridges are always (ion) conductive (may have large resistance, but never insulation).

[Shah]

So what makes electrons pass through the wire when we have closed circuit if the salt bridge is conductive???

[Nobby]

What cell do you have? copper/ zinc for example

Cu²⁺ + 2 e^- => Cu

Zn => Zn²⁺ + 2 e^-

Zinc gets oxidised and electrons will go through the wire to the copper electrode and copper ions will be reduced.

[Shah]

what i meant is why electrons traverse through the wires not through the salt bridge? both are conductive, aren't they?

[Nobby]

How does your cell looks like.   Normaly two compartments in one copper sulfate solution and a copper bar. and one with zinc sulfate and a zinc bare. conected are these with a salt bridge or to have better conductivity a wire.

The wire will go to the output.

Metalls better conductive as ionic solutions

[Shah]

do u mean that wires are more conductive than the solution in the salt bridge which makes electrons flow through these wires and not through the salt bridge???

[DevaDevil]

the salt bridge does not conduct "loose" electrons, only ions!

[Shah]

the salt bridge does not conduct "loose" electrons, only ions, is that due to its resistance ?

[DevaDevil]

that is because electrons cannot survive as entities in aqueous solution. Charge in solutions is carries by ions.

[Shah]

hence electrons can flow the salt bridge carried by ions, then what makes electrons traverse through the wires that conducts the two electrodes strips not through the salt bridge?

[DevaDevil]

Look at it this way:
Would it be likely that -for example- on a zinc electrode, zinc ions dissolve and electrons are "generated" in the electrode, then the electrons hook up to something (what did you have in mind) to hitchhike through the salt bridge to the counter electrode, where they are recombine with copper ions to make metallic copper.

Now
1)You would have a 2-way flow of identical charge in the salt bridge (remember, law of neutrality, you do not have a net charge buildup in any of the compartments), is this a likely thing to happen?

2) even IF that flow would be possible, think of resistance, which can be HUGE in a path through electrolyte (many hundreds of ohms unless the electrolyte is concentrated and the salt bridge cross area huge and the pathway small)

3) that would mean copper would not be created at the electrode (which is useless then), but at the interface of salt bridge/copper solution because there is the new junction, (we know this does not happen)