## Porous Wall

$E_{cell} = E_{cell}^{\circ}-\frac{RT}{nF}\ln Q$

Joonsoo Kim 4L
Posts: 61
Joined: Fri Sep 28, 2018 12:29 am

### Porous Wall

What does Dr. Lavelle mean by porous wall when talking about concentration cells, and how do they contribute to their function?

StudentD2B
Posts: 43
Joined: Fri Sep 28, 2018 12:27 am

### Re: Porous Wall

a concentration cell is a limited form of a galvanic cell that has two equivalent half-cells of the same composition differing only in concentrations. He might have been talking about concentration cell corrosion which occurs when two or more areas of a metal surface are in contact with different concentrations of the same solution. The area of the metal in contact with the low concentration of metal ions will be cathodic and will be protected, and the area of metal in contact with the high metal ion concentration will be anodic and corroded. I'm not entirely sure though

Kevin ODonnell 2B
Posts: 62
Joined: Fri Sep 28, 2018 12:24 am

### Re: Porous Wall

Hopefully this diagram will help depict it better than any words. The two solutions are separated by a porous barrier that prevents them from rapidly mixing but allows ions to diffuse through.

https://chem.libretexts.org/Bookshelves ... em1_(Lower)/16%3A_Electrochemistry/24.02%3A_Galvanic_cells_and_Electrodes
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Albert Duong 4C
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Joined: Fri Sep 28, 2018 12:17 am
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### Re: Porous Wall

I think the porous wall functions like a salt bridge in that it allows ions to move to the other electrode to even out the uneven charge distribution created by having too many electrons on one side. It's just that a porous disk tends to be used when the anode and cathode are in the same beaker and a salt bridge is for when the electrodes are separated. Either a porous disk or a salt bridge can be used for a concentration cell.

DHavo_1E
Posts: 118
Joined: Sat Aug 17, 2019 12:17 am

### Re: Porous Wall

Hello,

Could you explain why it’s important for the ions to diffuse through a porous barrier? Im a bit confused, do the electrons move through the external wire and the ions through the porous barrier/salt bridge? Thank you!

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