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What direction does electricity flow in electrolysis?

I'm doing past papers right now and I lost a mark because I said that in the electrolysis of brine the electricity flows from negative to positive.

In physics I learnt that although conventional current says it is positive to negative, in reality electricity flows from negative to positive.

Between all the 3 sciences and all the different experiments, which way should I say electricity flows? Why do we even bother with 'conventional' current if it's been disproven?
Original post by william91919
I'm doing past papers right now and I lost a mark because I said that in the electrolysis of brine the electricity flows from negative to positive.

In physics I learnt that although conventional current says it is positive to negative, in reality electricity flows from negative to positive.

Between all the 3 sciences and all the different experiments, which way should I say electricity flows? Why do we even bother with 'conventional' current if it's been disproven?


Yeah conventional current is the flow of positive charge i.e. opposite direction to electrons. The reason we use that is because all of electromagnetism and maxwell's equations are based on this convention and you'd need to rewrite all the textbooks from the last 100 years.

I think it wrong to say it's been "proven" it flows one way or another as it simply depends how you define current.

So what was the correct answer in your past paper?
Original post by william91919
I'm doing past papers right now and I lost a mark because I said that in the electrolysis of brine the electricity flows from negative to positive.

In physics I learnt that although conventional current says it is positive to negative, in reality electricity flows from negative to positive.

Between all the 3 sciences and all the different experiments, which way should I say electricity flows? Why do we even bother with 'conventional' current if it's been disproven?


Current flows in the opposite direction to electrons, just a quirk due to the history of it all. You come across a lot of these sorts of things in all walks of life.

The direction 'electricity' flows therefore depends on how you define it, I think the direction of electron flow is much more useful for electrolysis as you should have an idea about which electrode 'has excess' electrons and which accepts electrons.
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BJack
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Original post by william91919
I'm doing past papers right now and I lost a mark because I said that in the electrolysis of brine the electricity flows from negative to positive.


Caveat: the following is just my understanding of this and so may be hopelessly wrong. But it makes some intuitive sense, at least.

Electrons always (kind of) flow from the anode to the cathode. If you put that down, you should get the marks. (Although I have no idea if you actually *will* get the marks for putting that.) The issue comes from how we define positive and negative electrodes: the negative electrode is where you have excess electrons, basically.

In a galvanic cell, like you've come across in physics, this is the anode – as you'd probably expect. The anode is by definition where oxidation takes place, after all, and oxidation of the anode creates an excess of electrons there.

However in an electrolytic cell the excess we're interested in is for the electrode versus the electrolyte; the electrodes themselves are not oxidised/reduced. Clearly now the excess electrons are in the cathode, where they allow the cations to be reduced. By contrast, the anode is "positive" because excess electrons flow out of the electrolyte and into the anode.

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