Nernst Equation Calculator
Calculate cell potential under non-standard conditions using the Nernst equation. Solve for potential, concentration, or standard potential.
What is the Nernst equation?
The Nernst equation calculates the reduction potential of an electrochemical cell under non-standard conditions: E = E° - (RT/nF)ln(Q), where E is the cell potential, E° is standard potential, R is gas constant, T is temperature, n is electrons transferred, F is Faraday constant, and Q is reaction quotient.
When should I use the Nernst equation?
Use the Nernst equation when concentrations differ from standard conditions (1 M or 1 atm), when calculating cell potential at non-standard temperatures, for concentration cells, and when determining equilibrium constants from redox potentials.
What is the difference between E° and E?
E° (standard potential) is measured under standard conditions: 25°C, 1 M concentrations, 1 atm pressure. E (actual potential) is the measured potential under any conditions, calculated using the Nernst equation which accounts for non-standard concentrations and temperature.
What does n represent in the Nernst equation?
n is the number of moles of electrons transferred per mole of reaction. For example, in Zn + Cu²⁺ → Zn²⁺ + Cu, n = 2 (two electrons are transferred). You determine n from the balanced half-reaction.
How does temperature affect cell potential?
As temperature increases, the term (RT/nF)ln(Q) becomes larger, reducing the cell potential for exothermic reactions. Temperature also affects the equilibrium constant and reaction spontaneity. Most calculations use 298 K (25°C) as standard temperature.
What is the practical application of the Nernst equation?
The Nernst equation is used in designing batteries, understanding corrosion, calculating pH using electrode potentials, fuel cell operation, and determining ion concentrations in analytical chemistry (ion-selective electrodes).