Confusion over Electrolysis and Conventional current.

Chemistry and homework help forum.

Organic Chemistry, Analytical Chemistry, Biochemistry, Physical Chemistry, Computational Chemistry, Theoretical Chemistry, High School Chemistry, Colledge Chemistry and University Chemistry Forum.

Share your chemistry ideas, discuss chemical problems, ask for help with scientific chemistry questions, inspire others by your chemistry vision!

Please feel free to start a scientific chemistry discussion here!

Discuss chemistry homework problems with experts!

Ask for help with chemical questions and help others with your chemistry knowledge!

Moderators: Xen, expert, ChenBeier

Post Reply
QuantumWren
Newbie
Newbie
Posts: 3
Joined: Fri Nov 25, 2022 3:26 am

Confusion over Electrolysis and Conventional current.

Post by QuantumWren »

Hi, I am very confused about how conventional current integrates with Electrolysis. Conventional current is my absolute worse nightmare in science topics!

If there is an electrolysis set up with a cathode and anode, the cathode being attached to what is labeled as the negative terminal of the battery and the anode attached to the positive, then it is my understanding that the electrons are building up in the cathode (from the negative terminal) and as ions are discharged at the anode the electrons are going from the anode to the battery to then go to the cathode, thus resulting in a net positive charge for the anode.
Now that makes sense if the charge is travelling from negative to positive, i.e. electron flow, but that would not work for conventional current as the electrons; the electrons would be flowing from the positive terminal to the anode, building up at the anode and then discharging positive ions, so the anode would be negative! According to that the cathode would be positive as the electrons would be flowing away from the electrode to the negative terminal! After researching it I think that electrolysis diagrams tend to be drawn to conventional current, but the cathode is attached to the negative terminal and vice versa so that would appear to be for electron flow.
I'll use red for conventional current and blue for electron flow

The only thing is can think of is that the cathode should be connected to the positive terminal which is in fact supplying electrons and so the negative terminal and the inverse for the anode. But the diagrams so the cathode connected to a + energy source so that means either a) the labelling of the terminals is in electron flow in the diagram ( i.e. negative is actually negative etc), or b) the diagram is for electron flow.

I have included so drawings to illustrate why this confusion is a problem.
If it is conventional current then the anode is negative and the cathode is positive therefore if sodium chloride is the electrolyte then the discharged particles will be as follows: chlorine gas will be at the cathode on the right and and molten sodium will be at the left on by the anode. If electron flow the inverse will be true. So if I were to predict which product would be where I would need to know which current the diagram was using.

The absolute only thing I makes sense for me if the diagram is conventional current and the power source labeled are for conventional current with the negative terminal (which is positive in reality) attached to the anode and the positive terminal (which is negative) attached to the cathode, that way conventional current would predict the products to be in the same places as electron flow (as long as you flipped the power source over) But as I said, the diagrams do not show this!!!

As you can see, I am most utterly confused and would very much appreciate any help, I'm sorry this post is so long I hope that my description is detailed enough to convey my dilemma!
Perhaps a good question to start with would be: are batteries labelled for conventional or electron flow? (i.e is the side with the + actually positive in reality?)

I am very aware that I might be completely wrong about all of this so please don't be shy to correct if so!

Thank you! :D
Attachments
Electrolysis diagrams.
Electrolysis diagrams.
New Note.png (262.83 KiB) Viewed 56 times
User avatar
ChenBeier
Distinguished Member
Distinguished Member
Posts: 1201
Joined: Wed Sep 27, 2017 7:25 am
Location: Berlin, Germany

Re: Confusion over Electrolysis and Conventional current.

Post by ChenBeier »

First electrons are negatively charged and they will travel from a negative point to a positive one. So in an electrolysis the negative point is called cathode, the positive point is called Anode. The Anode is everytime the point where the oxidation chemically takes place.
So in the case of molten NaCl the electrons waiting on the cathode the negative point to catch the positive sodium ions to make them neutral to sodium metal (Na+ + e- => Na Reduction). On the Anode side the electrons are sucked from the positive charge, so the negative chloride ions touch there and release the electrons. Neutral chlorine will be developed (oxidation 2Cl- => 2 e- + Cl2 neutral).
That is what physical/ chemical takes place.
What you are thinking is the current in convential circuit flows from plus to minus. This idea came 200 years ago as Mr. Ampere or Volta defined the direction of current. But in that time they dont know electrons are existing neither they know the charge of them. By accident they choose the wrong direction for the flow. Plus to minus. This was never changed until today times. So for a physisit or chemist current goes with the electrons from minus to plus. For an electrician or Electronic guy its still plus to minus against the electron flow.
QuantumWren
Newbie
Newbie
Posts: 3
Joined: Fri Nov 25, 2022 3:26 am

Re: Confusion over Electrolysis and Conventional current.

Post by QuantumWren »

Thank you very much for your reply.
So are you saying that when talking about electrolysis conventional current can be completely ignored? It would make sense my in my physics and Chemistry textbooks it talks about conventional current a lot!
User avatar
ChenBeier
Distinguished Member
Distinguished Member
Posts: 1201
Joined: Wed Sep 27, 2017 7:25 am
Location: Berlin, Germany

Re: Confusion over Electrolysis and Conventional current.

Post by ChenBeier »

You have only to know current is the flow of electrons in an electrical field. They are negative charged and travel from minus to plus. The Anode is the place where the oxidation takes place and the cathode is the reduction place. In electronics or electric the current flow from plus to minus. Not mentioned about electrons.
QuantumWren
Newbie
Newbie
Posts: 3
Joined: Fri Nov 25, 2022 3:26 am

Re: Confusion over Electrolysis and Conventional current.

Post by QuantumWren »

Ah okay. Thank you!
Post Reply