Electrolytic Cell: Anode, Cathode & Charge Explained

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In summary, the conversation discusses the concept of electrode charges and potential differences. The anode has a positive charge and attracts anions, even though electrons are constantly flowing out of it. This is because the potential difference creates a charge difference. The second question is about electrodeposition and the reduction of metal cations on the cathode. This process causes a flow of current into the cathode, indicating the metal concentration in the solution. The understanding is correct, as the metal cations do not flow back into the solution due to the lack of forces holding them onto the glassy carbon electrode. The conversation also touches on the misconception that the presence of electrons automatically makes something negative.
  • #1
kristof
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Hello

Please help me with this.

Cathode has negative charge, anode has positive charge. Electrons travel from anode to cathode.

Question 1: why is anode positive and attracts anions? How can the charge build up on this electrode if electrons are constantly flowing out of this electrode? If it has constant supply of electrons, then it also should be negative.. I would understand that anions would be attracted to it if the charge was fixed and positive. I understand that there would be a lack of electrons causing positive charge at anode and negative at cathode. But I don't understand what causes anode to be of positive charge.

If you can, please answer also the second question:
Question 2: During electrodeposition on the cathode, a potential is appied and metal cations become reduced to zero charge (in anodic stripping voltammetry). In case of using glassy carbon electrode, they are deposited on the electrode and stripped back into the solution which causes faradaic current to flow into the cathode and is indicative of the metal concentration in the solution. Is that correct understanding of this? If so, when the metal cations are becoming reduced at cathode, why they don't flow back into the solution? There are no forces holding them onto the glassy carbon electrode (no amalgamate is formed).
 
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  • #2
kristof said:
why is anode positive and attracts anions? How can the charge build up on this electrode if electrons are constantly flowing out of this electrode?

If you observe potential difference, you can be sure there is a charge difference - by the definition of potential. So apparently there is something wrong with the idea that flowing electrons mean no charge difference, as half of physics would be wrong if you were right.

Think about the situation we observe when there is a water flowing between two tanks located at different heights. When the water level difference is zero, water doesn't flow, but you need some time to reach that point, as the flow speed is not unlimited. Situation with the electrodes and charges is not identical, but in many ways analogous.
 
  • #3
Thanks Borek, I didn't say I'm right , I said I just don't get it. Still don't get it. Even if there is charge difference due to potential difference, why is the anode positive if eletrons are flowing out of it constantly? If electrons are flowing through it and coming out of it , why is it not negative?
 
  • #4
It is "positive" relative to cathode, doesn't mean it is really positive.

Besides, presence of electrons doesn't make something automatically negative, Fe2+ is positive even if it has 24 electrons.
 
  • #5
of course! thanks Borek, why didn't I think about it already.
 

1. What is an electrolytic cell?

An electrolytic cell is a type of electrochemical cell that uses electricity to cause a non-spontaneous redox reaction to occur. It consists of two electrodes (anode and cathode) immersed in an electrolyte solution.

2. What is the purpose of an anode and a cathode in an electrolytic cell?

The anode is the electrode where oxidation (loss of electrons) takes place, while the cathode is the electrode where reduction (gain of electrons) occurs. These reactions are essential for the flow of electricity in the cell.

3. How does an electrolytic cell charge work?

An electrolytic cell is charged by connecting an external power source, such as a battery, to the anode and cathode. This causes the anode to become positively charged and the cathode to become negatively charged, allowing the flow of electrons between them.

4. What happens to the anode and cathode during the electrolysis process?

During the electrolysis process, the anode loses mass as it is oxidized, while the cathode gains mass as it is reduced. This is due to the transfer of ions from the anode to the cathode through the electrolyte solution.

5. Can an electrolytic cell be used for energy storage?

No, an electrolytic cell is not suitable for energy storage as it requires a constant external power source to function. It is commonly used for industrial processes such as electroplating and metal refining.

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