Nernst Equation
Definition and meaning of Nernst Equation in chemistry.
The Nernst equation is a fundamental electrochemical formula that relates the reduction potential of a half-cell at any given concentration to the standard electrode potential, temperature, and the activities of the participating chemical species. It is widely used to determine cell potentials under non-standard conditions.
In more detail
This mathematical equation demonstrates how the voltage of an electrochemical cell changes as the concentration of reactants and products shifts during a chemical reaction. It incorporates the ideal gas constant, temperature, the number of moles of electrons transferred, and the Faraday constant to calculate cell potential. As a battery discharges and the reactant concentrations decrease, the Nernst equation accurately predicts the corresponding drop in cell voltage until chemical equilibrium is reached and the voltage hits exactly zero.
Key facts
| Field | Physical Chemistry |
|---|---|
| Formula | E = E0 - (RT/nF)lnQ |
| Application | Determining cell potential under non-standard conditions |
Calculating the exact voltage of a copper-zinc galvanic cell when the concentration of Cu2+ ions is 0.5 M instead of the standard 1.0 M requires the application of the Nernst equation.
Frequently asked questions
What does Q represent in the Nernst equation?
Q is the reaction quotient, which is the ratio of the product concentrations to the reactant concentrations at a given moment.