Concentration cell

Definition

A concentration cell is an electrochemical cell where both electrodes are made of the same material, but they are immersed in electrolytes of different concentrations. The potential difference between the two half-cells drives the electron flow.

5 Must Know Facts For Your Next Test

1. The potential difference in a concentration cell is due to the difference in ion concentration between the two half-cells.
2. Nernst equation is used to calculate the cell potential for a concentration cell: $E = E^0 - \frac{RT}{nF} \ln Q$.
3. In concentration cells, $E^0$ (standard electrode potential) is zero because both electrodes are identical.
4. Concentration gradients drive spontaneous reactions until equilibrium is achieved, resulting in zero net voltage.
5. Common examples include galvanic cells with different concentrations of copper sulfate or hydrogen ion solutions.

Review Questions

• What causes the potential difference in a concentration cell?
• How does the Nernst equation apply to a concentration cell?
• Why is $E^0$ zero in a concentration cell?

Related terms

Electrochemical Cell:

A device that generates electrical energy from chemical reactions or facilitates chemical reactions through the introduction of electrical energy.

$E^0$ (Standard Electrode Potential): The measure of individual potential of a reversible electrode at standard state conditions, typically measured against a standard hydrogen electrode.

Nernst Equation:

$$E = E^0 - \frac{RT}{nF} \ln Q$$, an equation that relates the reduction potential of an electrochemical reaction to the standard electrode potential, temperature, and activities (or concentrations) of the chemical species involved.