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### Course: Class 12 Chemistry (India)>Unit 2

Lesson 3: Cell potentials at nonstandard conditions

# Concentration cell

Concentration cells are galvanic (or voltaic) cells made of two half-cells, each of which containing the same electrodes, but different concentrations. Concentration cells work to establish equilibrium by transferring electrons from the cell with the lower concentration to the cell with the higher concentration. The electrode potential difference between the two half-cells can be calculated using the Nernst   equation. Created by Jay.

## Want to join the conversation?

• How can I solve for a missing concentration in the Nernst Equation?
• just substitute Q as [product]/[reactant]
and then solve for conc. of product or reactant which ever is required
• At , what would Q be equal to? Why is less divided by more? You did not explain the logic of why this is the case. If we reverse the equation, then Q would equal more divided by less.
• Because in the overall reaction, [Zn2+] of lower concentration is the product, and for Q products are in the numerator
• why is it positive? what happens to the negative multiplying .0592?
• log(0.1/10) is a negative number. negative * negative = positive
• Why will the initial potential be 0? at , he says the concentrations are same, but for the oxidation half, the concentration is 0.10 M while in the reduction half cell, the concentration is 1.0 M. Right?
(1 vote)
• At , he's referring to the standard cell potential i.e., the cell potential you get when the experiment is conducted at standard conditions. He started off with the experiment we're concerned with (the one with 0.1 M and 1.0 M concentrations in the containers), in which the initial potential will not be zero. But at , he was talking about the standard cell potential, so that we can plug it into 'E^0' in the Nernst Equation. In the case of the standard cell potential, the concentrations would be the same.
• Why do the solutions tend to equalize their concentration?
• beco'z anything in this universe wants to be in equilibrium according to Le Chatelier's principle so they wants to equalise their concentrations by gaining or losing electrons.
• Can you please explain variation of conductivity andmolar conductivity with concentrations? ??
• At infinite dilution, conductivity is assumed to be maximum. Look up Kohlrausch's Law. Hope this helps.
-Cheers
(1 vote)
• How do you find cell potential using activities for a concentration cell. How do you know which is oxidation and reduction?
• You would have two half reactions; an oxidation half reaction and a reduction half reaction. Remember: oxidation is losing electrons, reduction is gaining electrons. So the half reaction that has some element or compound plus electrons on the REACTANTS side would be the reduction reaction. The half reaction with some element or compound plus electrons on the PRODUCTS side is the oxidation reaction. I hope that was helpful! :)
• At , Sorry, I couldn't catch this. Why is the Zn 2plus cation 1.0 molar? For the oxidation half reaction, isn't it 0.1 Molar?
(1 vote)
• What Jay says is correct because he's calculating E°, which the cell potential under standard conditions, defined as 1.0 M concentrations for ions on either side of the salt bridge.