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Author: Subject: low tech electrochem cell
morganism
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[*] posted on 2-8-2014 at 16:40
low tech electrochem cell


This is a great design, and looks like a great school project.
No permeable membrane required, just use filter paper !


http://m.phys.org/news/2014-07-salinity-gradient-power-cell-...
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Artemus Gordon
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[*] posted on 3-8-2014 at 12:23


So one half-cell oxidizes Zn atoms and the other half-cell reduces Zn ions? How is that not a perpetual motion machine; in other words, impossible?

BTW, using paper as the barrier is not novel, many commercial batteries use a paper separator. You just have to make sure you don't get any leakage around the edges.


[Edited on 3-8-2014 by Artemus Gordon]
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Metacelsus
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[*] posted on 3-8-2014 at 13:41


The concentration difference is what generates the voltage.

https://en.wikipedia.org/wiki/Nernst_Equation
https://en.wikipedia.org/wiki/Concentration_cell
https://en.wikipedia.org/wiki/Liquid_junction_potential

[Edited on 3-8-2014 by Cheddite Cheese]




As below, so above.
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Artemus Gordon
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[*] posted on 3-8-2014 at 14:05


Oh! So instead of a flow of ions arising to balance the electron flow of a conventional galvanic cell, in this case an electron flow arises to balance the spontaneous ion flow due to the concentration gradient?
Wiki mentions that this can be used to measure ion concentration. Is there any other practical use for such a cell, or is it mostly just used as a demonstration of the Nermst Equation?

EDIT: Please ignore the second question. I just read the end of the original linked article, which I had missed before.

[Edited on 3-8-2014 by Artemus Gordon]
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