⚗️ Nernst Equation — Galvanic Cell Potential Interactive Simulation

E° is the standard cell potential for the chosen electrode pair, R is the gas constant, T is absolute temperature, n is the number of electrons transferred per reaction (set by the electrode preset), F is Faraday's constant, and Q is the reaction quotient built from the current oxidant and reductant concentrations.

Increasing oxidant concentration or decreasing reductant concentration lowers Q. Since E subtracts a term proportional to ln Q, a smaller Q means a smaller subtraction and therefore a higher E — physically, the reaction has more driving force left to reach equilibrium.

Zinc oxidises at the anode (Zn → Zn²⁺ + 2e⁻, E° = −0.76 V) while Cu²⁺ reduces at the cathode (Cu²⁺ + 2e⁻ → Cu, E° = 1.10 V), joined by a salt bridge to complete the circuit. As the reaction proceeds, Zn²⁺ concentration rises and Cu²⁺ falls, so Q increases and E gradually decreases toward zero at equilibrium.

ΔG = −nFE converts the cell potential into Gibbs free energy, the standard thermodynamic measure of whether a reaction is spontaneous. A positive E (spontaneous galvanic cell) always corresponds to a negative ΔG, and the equilibrium constant K is the point where ΔG = 0 and E = 0.

Temperature appears directly in the RT/nF prefactor, so raising T amplifies how much ln Q shifts the potential away from E°. At higher temperatures, the same concentration imbalance produces a larger deviation from the standard potential than it would at room temperature.