[o1ocups]

The following is from this website: http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0031622.html

In chemistry, the production of chemical changes by passing an electric current through a solution or molten salt (the electrolyte), resulting in the migration of ions to the electrodes: positive ions (cations) to the negative electrode (cathode) and negative ions (anions) to the positive electrode (anode).

During electrolysis, the ions react with the electrode, either receiving or giving up electrons. ...

I have summarized my understanding about this in the following statements. Could anyone varify if they are true? And/or answer some of my questions?

-Electric current = flowing electrons
-Electrons go through a solution/molten salt
-A solution/molten salt = electrolyte = an agglomeration of separate ions
-Electrolyte connects the anode and the cathode
-The flowing electrons pass through the electrolyte
-These electrons somehow (how?) migrate the ions in the electrolyte in the following manner:
   -Positive ions/cations to cathode (I don't understand why it's negative here though)
   -Negative ions/anions to anode (same here I don't understand why it's positively charged)
-Cathode and anode are electrodes, which are usually solid rods or plates (but what about in water electrolysis?)
-The ions become neutral: the cations gain electron at the cathode, and the anions lose electron at the anode
-After either gaining or losing electron, something forms at the electrode (usually in solid or gas state)
-What's the situation now? What's in the electrolyte?

Thank you so much!!

[Borek]

-Electrons go through a solution/molten salt

No. Apart from some exotic situations there are no free electrons in solutions nor molted salts. Charge is transferred by migrating ions. For the electrons to enter and leave the solution/molted salt they have to react on the electrodes with whatever is available.

   -Positive ions/cations to cathode (I don't understand why it's negative here though)
   -Negative ions/anions to anode (same here I don't understand why it's positively charged)

Names of anode and cathode are only a convention. One that I never remember. The older I get the less likely it is I will get it one day. But in electrolysis seems like cathode attracts cations, so it have to be negative. It is just about Coulomb forces.

-Cathode and anode are electrodes, which are usually solid rods or plates (but what about in water electrolysis?)

Electrodes period. Rods, plates, liquid mercury - it doesn't matter.

-The ions become neutral

Not necesarilly. Fe³⁺ can get reduced to Fe²⁺ and it doesn't become neutral. Still, it got an electron from the cathode.

-After either gaining or losing electron, something forms at the electrode (usually in solid or gas state)

Not necesarilly, see above.

-What's the situation now? What's in the electrolyte?

Whatever didn't reacted at neither anode or cathode. Could be that means just water.

[o1ocups]

In my original quote, it says "...passing an electric current through a solution or molten salt" and that's why I thought there were electrons flowing through them. So the source of electron current or battery is connected to the electrodes not the electrolyte, right? That's what I thought, originally, too. Is that why the electrodes attract the ions? (the battery is sucking electrons from anode making it positively charged and attractive to anions, the battery is also giving those electrons to the cathode making it negatively charged and attractive to cations?)

And I just want to clarify something: the construction of an electrolytic cell is basically just two electrodes immersed in one container of electrolyte right? Because I'm not sure how else the anions can flow around either to cathode or anode. In other words, the concept of salt bridge etc. doesn't apply here right?

[Borek]

So the source of electron current or battery is connected to the electrodes not the electrolyte, right?

Electrodes serve as contact to the electolyte, but they can't pass the charge without reaction taking place.

the battery is sucking electrons from anode making it positively charged and attractive to anions, the battery is also giving those electrons to the cathode making it negatively charged and attractive to cations?

Again - that's convention and you will not force me into stating "yes, that's the cathode" But you get the process behind right.

And I just want to clarify something: the construction of an electrolytic cell is basically just two electrodes immersed in one container of electrolyte right? Because I'm not sure how else the anions can flow around either to cathode or anode. In other words, the concept of salt bridge etc. doesn't apply here right?

It doesn't matter. You can prepare electrolytic cell with two separated containers and connect them with salt bridge. It is not necessary, but it will not stop the electrolysis.

Salt bridge is necessary when you want to separate two solutions. Imagine you have solution of Fe²⁺ and solution of Ce⁴⁺. If you mix them, they will react in the solution and you will end with Fe³⁺ and Ce³⁺. What you want to do, is to force the charge to pass outside of the solution, to be able to use it. So you have to connect solutions electrically, but keep them separated mechanically, so that they don't mix. If you put them in a separate containers and connect them with a salt bridge they still can't react directly - even if they are eager to - but they are already electrically connected. However, circuit is not closed yet. To close it you put connected electrodes into both solutions. Then reaction takes place - just instead of electrons being exchanged directly between cations in the solution, they are forced to flow around, through the wire, and at the same time charge (in the forms of inert ions) flows through the salt bridge.

[o1ocups]

Thanks for the explanation; that really cleared things up 

However, I don't really understand this:

Then reaction takes place - just instead of electrons being exchanged directly between cations in the solution, they are forced to flow around, through the wire, and at the same time charge (in the forms of inert ions) flows through the salt bridge.

So you mean the electrons that are transferred to the cathode (by the battery) flow back to the anode through the salt bridge in the form of the ions in the salt bridge (I don't know what are inert ions) ?

[o1ocups]

Also, in a case where you are plating something (e.g. with gold), is it almost like the anode is dissolving with oxidation?

[Borek]

Then reaction takes place - just instead of electrons being exchanged directly between cations in the solution, they are forced to flow around, through the wire, and at the same time charge (in the forms of inert ions) flows through the salt bridge.

So you mean the electrons that are transferred to the cathode (by the battery) flow back to the anode through the salt bridge in the form of the ions in the salt bridge (I don't know what are inert ions) ?

Sorry, what I wrote was about galvanic cell, not about electrolysis.

However, these are in fact two sides of the same coin, just in one case you force the current to flow, in other case it flows spontaneously.

Inert ions are those not taking part in the reaction itself. However, they can still transfer charge, migrating fron one place in teh solution to other.

In general - don't think just about electrons. Think in terms of charge. Flowing current means flowing charge, be it electrons or other charged entities. Electrons can flow in conductors - like wires - so they do. They can't flow in the solution. However, ions can move through the solution, so they close the circuit.

Also, in a case where you are plating something (e.g. with gold), is it almost like the anode is dissolving with oxidation?

It depends. You can have just a solution containing enough of the plating metal, so that it will be not consumed before the plating is finished, you can have an anode that dissolves replenishing the metal in the solution. Which method you will use will depend on the circumstances, it is not that one is correct the and other is wrong.

[o1ocups]

OK I think I'll take your advice not to think in terms of electrons but the charge, because that was really confusing to me.

So in an electrolytic cell where you separate the two solutions, can you use a salt bridge, or no?

[Borek]

So in an electrolytic cell where you separate the two solutions, can you use a salt bridge, or no?

You don't have to. In electrolytic cell you have usually one solution and there is no need to separate it. However, if - for whatever reasons - you will decide that you want to use different solutions for anode and cathode reactions, there is no a single reason why separating both solutions with salt bridge will not work.

It may be difficult in practice, but there is no reason that prohibits such a setup.

[o1ocups]

OK Thanks.