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### Concentration Cells

Posted: Sun Mar 01, 2020 4:47 pm
Can someone explain to me how concentration cells are different from the regular galvanic cells we learned about in class? Also, why is the standard cell potential 0 in these types of cells?

### Re: Concentration Cells

Posted: Sun Mar 01, 2020 6:16 pm
I think the primary difference between concentration cells and galvanic cells is that the aqueous solution and the electrodes are the same, just in difference concentrations. In this case, the cell potential isn't coming from the difference in standard potentials for the electrodes, but rather the difference in concentration.
The standard cell potential is 0 since both electrodes are the same.

### Re: Concentration Cells

Posted: Sun Mar 01, 2020 6:20 pm
in a concentration cell the two electrodes have the same composition but different compositions. By measuring Ecell the concentration of the left electrode can be determined. If this concentration is less than at the right, then Ecell will approach 0 and the right electrode will be the cathode.

### Re: Concentration Cells

Posted: Sun Mar 01, 2020 9:24 pm
While galvanic cells have different ions reacting on the cathode and anode, concentration cells have the same species on either side, but the concentrations are different. That's why it's called a concentration cell.
The standard cell potential of a concentration cell is 0 because the reactions are exactly the same on either side, just reversed. This means that they have the same standard potential values. Using the equation $E^{\circ}_{cell}=E^{\circ}_{cathode}-E^{\circ}_{anode}$, the 2 values cancel out and Ecell is 0.

### Re: Concentration Cells

Posted: Sun Mar 01, 2020 9:30 pm
The only reason that electrons flow is because of a difference in the concentration of the cells. They have the same species, which makes them generally have a lower E value than regular galvanic cells.