Flow of electrons

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Mya Majewski 1L
Posts: 89
Joined: Fri Sep 25, 2015 3:00 am

Flow of electrons

Postby Mya Majewski 1L » Tue Mar 12, 2019 11:51 pm

When is the flow of electrons NOT from anode to cathode? In 6th edition 14.91 it flows from cathode to anode?

David Effio 1H
Posts: 38
Joined: Wed Feb 14, 2018 3:01 am

Re: Flow of electrons

Postby David Effio 1H » Wed Mar 13, 2019 1:47 am

The cathode is always the site of reduction, hence electrons flow towards it, and the anode is always the site of oxidation, hence electrons flow away from it. The only time that they flow the opposite way is when an electrical current causes the non-favorable process to occur, driving electrons the opposite way, and essentially making the cathode into the anode, as it is losing electrons, and the anode into the cathode, as it is gaining electrons.

This is similar to the process of charging your computer/phone's battery, where electrical current is input, causing electrons to flow in the opposite direction they would normally do favorably. This requires electrical energy and reverses the cathode and anode. However, once electrical input ceases, the battery will continue its favorable process, where the electrons will flow from the strongest reducing agent (oxidized, anode) to the strongest oxidizing agent (reduced, cathode).

In short, it's not that the electrons flow from cathode to anode, but that the anode and the cathode simply switch places for the time that electrical energy is being applied to the cell.

Amar Singh
Posts: 31
Joined: Fri Sep 28, 2018 12:20 am

Re: Flow of electrons

Postby Amar Singh » Sat Mar 16, 2019 11:33 pm

One way to think of it is that cathode is +, so electrons are being added to it.

The anode is -. so electrons are being removed from it.

The electron from will go from the site being removed (anode) to the site where the electrons are added (cathode).

Leslie Almaraz 4G
Posts: 99
Joined: Fri Aug 02, 2019 12:16 am

Re: Flow of electrons

Postby Leslie Almaraz 4G » Fri Feb 28, 2020 3:32 pm

does the flow of electrons indicate which of the metal pieces is being eroded in the solutions?

Ashley Wang 4G
Posts: 103
Joined: Wed Sep 11, 2019 12:16 am

Re: Flow of electrons

Postby Ashley Wang 4G » Sun Mar 01, 2020 9:44 pm

Leslie Almaraz 4G wrote:does the flow of electrons indicate which of the metal pieces is being eroded in the solutions?

I think if the metal conductor is one of the species taking part in the reduction/oxidation, then its size will change. However, if there is no conducting solid in the reaction and platinum is used, then its size won't change since it is chemically inert.

For example, for the cell represented by Cu(s) I Cu2+ (aq) II Fe3+, Fe2+ I Pt (s)
electrons are flowing from the anode to the cathode, so the Cu electrode is getting smaller as Cu is oxidized to Cu2+ as electrons are pulled from it. At the cathode, the inflow of electrons is changing the concentration of Fe2+ and Fe3+ in solution, but isn't changing the size of the Pt electrode.

I hope this helps!

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