Home >
Community >
Linking an electrochemical cell to an electrolytic cell
Upvote
VOTE
Downvote
+ Electrolysis
+ Chemistry
+ Electrochemistry
Posted by
Ahad Bajkani
Linking an electrochemical cell to an electrolytic cell
You seem to be mixing a couple of things. One important clarification regarding
Also, seeing that the MnO2 cathode has a relatively small E$^o$ value, won't it be hard to trigger oxidation of the electrolytic anode? When connected to the electrolytic cell, do the cathode and anode of the electrochemical cell now work totally independently?
The listed electrode potentials are valid only in relatively dilute solutions under very specific conditions. Don't apply the half cells on a dry cell or an alkaline cell. In short, those numbers are not meaningful for an alkaline battery or a carbon-zinc dry cell. Those commercial cell compositions is just a magical mixture, which is more art than science. Battery technology is not that trivial. Think why there are not many types of batteries despite 300 years of research?
If you consider a galvanic cell such as your alkaline battery as a simple water pump, then a lot of your confusions will go away. Its only job is to "circulate" the electrons. When you connect a galvanic cell to an electrolytic cell, the anode and cathodes can no longer be considered independent. If the galvanic cell pumps out one electron, the electron has to travel the cathode, anode and the external circuit of the electrolytic cell. In that process, something in the electrolytic cell has to chemically decompose!
You seem to be mixing a couple of things. One important clarification regarding
Also, seeing that the MnO2 cathode has a relatively small E$^o$ value, won't it be hard to trigger oxidation of the electrolytic anode? When connected to the electrolytic cell, do the cathode and anode of the electrochemical cell now work totally independently?
The listed electrode potentials are valid only in relatively dilute solutions under very specific conditions. Don't apply the half cells on a dry cell or an alkaline cell. In short, those numbers are not meaningful for an alkaline battery or a carbon-zinc dry cell. Those commercial cell compositions is just a magical mixture, which is more art than science. Battery technology is not that trivial. Think why there are not many types of batteries despite 300 years of research?
If you consider a galvanic cell such as your alkaline battery as a simple water pump, then a lot of your confusions will go away. Its only job is to "circulate" the electrons. When you connect a galvanic cell to an electrolytic cell, the anode and cathodes can no longer be considered independent. If the galvanic cell pumps out one electron, the electron has to travel the cathode, anode and the external circuit of the electrolytic cell. In that process, something in the electrolytic cell has to chemically decompose!
So what I understand about this is that alkaline cells cannot be thought of as just a simple anode and cathode, and are more than the sum of its parts. Also, kinda dumb question; for linking a galvanic cell to a electrolytic one, you mentioned that the electron travels from the cathode to the anode. If you can detail this process a bit more, I would be very grateful.More
I have another doubt, sorry to bother. I have pinned a picture onto the post, which supposedly shows a galvanic cell linked to an electrolytic cell. The way this is set up is as if the anode of the galvanic cell and the cathode of the electrolytic cell act as a separate cell altogether, same goes with the other two electrodes. If what you said is true and the electrons travel a full circuit (galvanic anode to galvanic cathode), how are the cells linked?More
Upvote
VOTE
Downvote
For an electrolytic cell, a galvanic cell is nothing else but a power source.
For a galvanic cell, an electrolytic cell is nothing else but a powered electronic circuit.
The galvanic cell anode/cathode does not form with the electrolytic cell cathode/anode a respective separate cell, as there is no ionic flow between them. Similarly for a simpler case, 2 half cells do not form a cell if there is no ionic connection between them.
The reason for it is simple, based on the electrostatic neutrality requirement and enormous forces between unbalanced charges. Imagine you managed to push the current 1 A for 20 s through the wire, without being balanced by ionic motion. The comparable unbalanced charge causes in atmosphere a lightning several kilometres long.
For an electrolytic cell, a galvanic cell is nothing else but a power source.
For a galvanic cell, an electrolytic cell is nothing else but a powered electronic circuit.
The galvanic cell anode/cathode does not form with the electrolytic cell cathode/anode a respective separate cell, as there is no ionic flow between them. Similarly for a simpler case, 2 half cells do not form a cell if there is no ionic connection between them.
The reason for it is simple, based on the electrostatic neutrality requirement and enormous forces between unbalanced charges. Imagine you managed to push the current 1 A for 20 s through the wire, without being balanced by ionic motion. The comparable unbalanced charge causes in atmosphere a lightning several kilometres long.
I think Im catching your drift now! So for the image above, since there isnt a salt bridge or something of the sort, for each electron used to reduce a cation in the electrolytic cell, an electron is produced by oxidation of an anion, as to maintain neutrality of charge. Am I getting this right?More
If there were charge disbalance, it would very quickly build an electrostatic potential acting against the charge flow leading to such a disbalance, and the current would cease.More
Like that You can consider the galvanic cell as a water pump and the electrolytic cell as the piping system. But there is circulation of charge,instead of water.More
Therefore, the galvanic cell as a whole is used to drive electrons into the electrolytic anode and out the electrolytic cathode. Makes much more sense if thats the case!More
You seem to be mixing a couple of things. One important clarification regarding
The listed electrode potentials are valid only in relatively dilute solutions under very specific conditions. Don't apply the half cells on a dry cell or an alkaline cell. In short, those numbers are not meaningful for an alkaline battery or a carbon-zinc dry cell. Those commercial cell compositions is just a magical mixture, which is more art than science. Battery technology is not that trivial. Think why there are not many types of batteries despite 300 years of research?
If you consider a galvanic cell such as your alkaline battery as a simple water pump, then a lot of your confusions will go away. Its only job is to "circulate" the electrons. When you connect a galvanic cell to an electrolytic cell, the anode and cathodes can no longer be considered independent. If the galvanic cell pumps out one electron, the electron has to travel the cathode, anode and the external circuit of the electrolytic cell. In that process, something in the electrolytic cell has to chemically decompose!
You seem to be mixing a couple of things. One important clarification regarding
The listed electrode potentials are valid only in relatively dilute solutions under very specific conditions. Don't apply the half cells on a dry cell or an alkaline cell. In short, those numbers are not meaningful for an alkaline battery or a carbon-zinc dry cell. Those commercial cell compositions is just a magical mixture, which is more art than science. Battery technology is not that trivial. Think why there are not many types of batteries despite 300 years of research?
If you consider a galvanic cell such as your alkaline battery as a simple water pump, then a lot of your confusions will go away. Its only job is to "circulate" the electrons. When you connect a galvanic cell to an electrolytic cell, the anode and cathodes can no longer be considered independent. If the galvanic cell pumps out one electron, the electron has to travel the cathode, anode and the external circuit of the electrolytic cell. In that process, something in the electrolytic cell has to chemically decompose!
More
VOTE
VOTE
VOTE
VOTE
VOTE
VOTE
For an electrolytic cell, a galvanic cell is nothing else but a power source.
For a galvanic cell, an electrolytic cell is nothing else but a powered electronic circuit.
The galvanic cell anode/cathode does not form with the electrolytic cell cathode/anode a respective separate cell, as there is no ionic flow between them. Similarly for a simpler case, 2 half cells do not form a cell if there is no ionic connection between them.
The reason for it is simple, based on the electrostatic neutrality requirement and enormous forces between unbalanced charges. Imagine you managed to push the current 1 A for 20 s through the wire, without being balanced by ionic motion. The comparable unbalanced charge causes in atmosphere a lightning several kilometres long.
For an electrolytic cell, a galvanic cell is nothing else but a power source.
For a galvanic cell, an electrolytic cell is nothing else but a powered electronic circuit.
The galvanic cell anode/cathode does not form with the electrolytic cell cathode/anode a respective separate cell, as there is no ionic flow between them. Similarly for a simpler case, 2 half cells do not form a cell if there is no ionic connection between them.
The reason for it is simple, based on the electrostatic neutrality requirement and enormous forces between unbalanced charges. Imagine you managed to push the current 1 A for 20 s through the wire, without being balanced by ionic motion. The comparable unbalanced charge causes in atmosphere a lightning several kilometres long.
More
VOTE
VOTE
VOTE
VOTE
VOTE