Discharge vs Recharge in Galvanic Cell

[MedicalMan14]

Am I correct in the following: Discharge means the reaction goes in the direction it wants to (in galvanic cells, thus the forward positive potential direction), and recharge means it travels in the opposite direction?

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[TieuBachHo]

Am I correct in the following: Discharge means the reaction goes in the direction it wants to (in galvanic cells, thus the forward positive potential direction), and recharge means it travels in the opposite direction?

Discharge is when you want something to become neutral; and recharge is when you want to polarize it. Becareful with galvanic and electrolytic cells, some batts are never meant to be recharged LOL.

 

[MedicalMan14]

um ok; so if a question says a battery is discharging, am I to assume that the reaction that (with positive electric potential) occurs at the anode with oxidation & electron movement towards cathode. Is that discharging? I am confused as to determine when something is recharging or discharging by looking at it. Can you give me a general idea?

 

[TieuBachHo]

um ok; so if a question says a battery is discharging, am I to assume that the reaction that (with positive electric potential) occurs at the anode with oxidation & electron movement towards cathode. Is that discharging? I am confused as to determine when something is recharging or discharging by looking at it. Can you give me a general idea?

Just be careful when you use them for Galvanic or Electrolytic cells. Discharging means a spontaneous movement of electrical charges from a higher potential to a lower potential.

 

[MedicalMan14]

Why the caution with Galvanics?

 

[TieuBachHo]

Why the caution with Galvanics?

Well, just a reminder of conventional use for Anode and Cathode. Just know the difference, that's all. Some ppl prefer them in term of potentials; while others like to refer them in term of pos. or neg.

 

[Mopped]

In a rechargeable battery, the cell acts as a galvanic cell when discharging and an electrolytic cell when being charged.

In a discharging battery (or a galvanic cell), the cathode is the positive terminal

In a recharging battery (or an electrolytic cell), the cathode is the negative terminal.

Remember, this NEVER changes:
Cathode = Reduction = Gains electrons
Anode = Oxidation = Loses electrons

Hope this helps someone.

 

[movax]

This is what I use to keep things straight (I am an electrical engineer, so Ben Franklin's mistake 200+ years ago is especially irritating 😛)

Anode - ACID - Anode Current Into Device. ALWAYS TRUE.
In a galvanic cell (so a standard battery discharging) or voltage source, anode will be negative, because that's where current flows into the device.

In a recharging battery, anode will be positive, because current is flowing into the cell to recharge it.

In a diode, it will be the positive terminal, because that's where current flows into it. In a CRT, it will be where electrons exit (or current enters).

Cathode - CCD - Cathode Current Departs. ALWAYS TRUE.
Galvanic Cell - positive, since current is flowing out and into the circuit.
Recharging Battery - negative, since current has flowed through the battery and is now departing
Diode - negative terminal, since that's where current leaves
CRT - it's the electron gun end, shooting out electrons (and thusly where holes are leaving).

Therefore, since current enters at the anode (and electrons are leaving), remember losing electrons = oxidation (LEO goes GRR)) and the anode is where oxidation takes place. Likewise, since current departs at the cathode (and electrons are entering), remember gaining electrons = reduction (LEO goes GRR).

Remember this: Current is hole flow. Electrons go in the opposite direction of current. Holes are a theoretical construct used to model current flow (holes are not the opposites of electrons, that would be positrons).

e: oops, didn't see that above poster bumped this thread after a while. Hopefully this will help out someone though.