Cathode/Anode and Charges

[Chunkle]

So for both voltaic and electrolytic, electrons flow from anode to cathode, and oxidation occurs at the anode and reduction at the cathode. Also anions flow to the anode and cations to the cathode.

Both for voltaic, since the electrons flow from the anode to the cathode, the anode is negatively charged and the cathode is positively charged? (this is how TPR reasons it). Thus anode is electron deficient, so it is more positive for the anions to flow to and cathode is more negative for the cations to flow to?

And in a electrolytic cell, electrons are pumped by the battery so the anode is positively charged and cathode is negative? But then what are the ions doing.. I'm pretty sure it's still anions to anode and cations to cathode.

The review books are vague regarding this, so some clarification would be great.

Oh and also, the salt bridge allows for the flow of ions to complete complete the circuit correct? So without the salt bridge, there would be no constant current flow? And if there wasn't one, it would essentially be a capacitor in a sense?

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[V5RED]

Anode=area of oxidation=area of electron loss
Cathode=area of reduction=area of electron gain

In a Galvanic cell, this occurs spontaneously because the stuff in the cathode has a greater reduction potential than the stuff in the anode. This means it will draw electrons from the stuff in the anode through the wire more strongly than the stuff in the anode can try to draw electrons from the cathode(ie the cathode stuff wins the electron tug of war). Since the electrode in the anode does not have infinite electrons, it needs things to donate electrons to it or the reaction stops. The withdrawing of electrons from the electrode in the anode by the electrode in the cathode is why it draws anions toward itself.

If the donation stops or is not as fast as the electrons are withdrawn, then the anode will have a positive charge. The anode is sometimes called negative because it is easier for students to envision a negative thing repelling electrons, but if you replaced the stuff in the cathode with stuff with a lower reduction potential than the stuff in the anode, then the electron flow would reverse and the anode would become the cathode, so clearly the anode is not intrinsically negative.

In an electrolytic cell, this occurs because a battery forces the electrons to transfer. There is no difference between an electrolytic cell and a galvanic cell except that the driving force for the electron flow is a battery instead of the differential reduction potentials of the anode and cathode. The anode still loses electrons and becomes positive if they are not replaced fast enough and the cathode still gains electrons.

The salt bridge is needed because water can't be very charged and even if it could, if enough electrons flow into the cathode, then it will be negatively charged due to the excess negative charges and electrons would be repelled, so the reaction would stop.

I don't know about it being a capacitor if the salt bridge is gone, so I won't touch that one.