J.R. S. answered • 12/29/21
Ph.D. University Professor with 10+ years Tutoring Experience
So, I think what you are asking about has to do with oxidation and reduction potentials of the different elements/metals. We generally use a table of standard reduction potentials, and this describes how easily a metal will be reduced relative to hydrogen (the standard hydrogen electrode). For example, the standard reduction potential for Zn2+ + 2e- ==> Zn is -0.76 V. The standard reduction potential for Cu2+ + 2e- ==> Cu is +0.34 V. So Cu2+ is more easily reduced than is Zn2+. Reduction takes place at the cathode, so that would be the Cu electrode. Electrons will flow from the Zn electrode to the Cu electrode and that's how electrons are "formed" in the cathode, that is why they are "forming". They are coming from the Zn which is being oxidized.
So, in summary, it all boils down to which two metals you have connected and what the reduction or oxidation potentials of these two metals are.
J.R. S.
12/30/21
0825 2.
But I've read everywhere that cathodes are negatively charged electrodes..12/30/21
J.R. S.
12/30/21
0825 2.
ok12/31/21
Stanton D.
SO -- to clarify your basic question -- electrons are always present, and mobile, around the atoms of a metal. To have an electrochemical reaction, which occurs at the metal-solution interface, electrons either come from the reacting chemical ions in the solution into the electrode, or they go from the electrode into the solution as some form of ions. They do not travel as free electrons through the aqueous solution. They do travel approximately as free electrons through metals, but there are better ways of characterizing them in metals than as free particles.12/31/21
Stanton D.
The whole bit about galvanic vs. electrolytic cells terminology ("cathode" vs. "anode") is historical. If the cell is operating the direction it naturally wants to (with current flowing through a resistance in the wire connecting the half-cells), that's galvanic. But if you hook a battery into the connection wire and force current to run as the battery directs, that's electrolytic. Even if that's the same direction of current flow!!12/31/21
0825 2.
So you are saying that in this case, copper is the cathode and zinc is the anode. But when zinc is loosing electrons why would the electrons get attracted to the cathode?? Both are negative, so shouldn't they remain in the anode?12/30/21