Electrode Sign: + or -? Understanding Cell Potential

[pivoxa15]

Electrodes in cells usually have a sign of either + or -

My textbook talks about the + as because the electrode is positively charged and - when negatively charged. But is that correct? The electrodes are meant to be conductors and shouldn't be charged at any time. When they do, the ions leave them and migrate into the solution.

So the + or - should instead point to the cell with the higher (+) or lower potential (-) given by the table of redox reactions. Nothing to do with charges.

 

[chemisttree]

The resistance of the cell is greater than zero so the charge just naturally piles up on the negative electrode.

 

[pivoxa15]

How do you explain the positive electrode is mainly positively charged?

 

[chemisttree]

Strip away a few electrons and the remaining electrode has a net positive charge.

 

[+Minkie+]

It's not actually the charge they are talking about in your textbook, it's the flow of electrons.
Are you talking about a galvanic or an electrolytic cell?

 

[pivoxa15]

Strip away a few electrons and the remaining electrode has a net positive charge.

But the electrons are pepertually moving so when electrons are lost, new ones are added.

 

[pivoxa15]

It's not actually the charge they are talking about in your textbook, it's the flow of electrons.
Are you talking about a galvanic or an electrolytic cell?

I think it doesn't matter which. They use their explanation for both. I know that from a physics textbook, the + and - ends of a battery are not described as + charge or - charge but higher and lower potential for + and - respectively.

 

[+Minkie+]

It does matter.
In a galvanic cell the cathode is positive and the anode is negative.
In an electrolytic cell the cathode is negative and the anode is positive.

So we need to know whether your producing electricity from a cell, e.g. a battery.
Or putting electricity into a cell, e.g. electroplating.

 

[pivoxa15]

I think my textbook would say that cathode is positive => cathode is positively charged. cathode is negative => cathode is negatively charged. However, I like to intepret positive as higher potential and negative as lower potential. In this light I agree that (as you stated)

In a galvanic cell the cathode is positive and the anode is negative.
In an electrolytic cell the cathode is negative and the anode is positive.

So I disagree witht the textbook in this fundalmental point of intepretation.

 

[+Minkie+]

Possibly referring to when electrons are lost negative charge is lost, hence the atom they were lost from gains a positive charge.
I don't know why this would apply to the electrodes though, only the ions.

 

[pivoxa15]

Possibly referring to when electrons are lost negative charge is lost, hence the atom they were lost from gains a positive charge.
I don't know why this would apply to the electrodes though, only the ions.

That's the thing, in my view, the electrods should merely be charge carriers and be electrically neutral. Charge gained=charge lost at all times for an ideal electrode.

 

[+Minkie+]

Ya well I can't think of anything else, so I think it may be the textbook.
They don't get proof read very well so it is quite likely.