N

Nernst Equation

E = E° − (RT/nF)lnQ; at 25°C: E = E° − (0.0592/n)log Q
Quick Reference
Formula / NotationE = E° − (RT/nF)lnQ; at 25°C: E = E° − (0.0592/n)log Q
Also Known AsNernst equation, electrode potential equation, concentration cell formula

What is Nernst Equation?

An equation relating the electrode potential to the standard potential and the concentrations of reactants and products: E = E° - (RT/nF)ln(Q). At 25°C, this simplifies to E = E° - (0.0592/n)log(Q). Used to calculate cell potential under non-standard conditions.

Formula & Notation

E = E° − (RT/nF)lnQ; at 25°C: E = E° − (0.0592/n)log Q

Other Names / Synonyms: Nernst equation, electrode potential equation, concentration cell formula

Properties & Characteristics

The Nernst equation relates the electrode potential (E) of an electrochemical cell or half-cell to the standard electrode potential (E°) and the reaction quotient (Q): E = E° − (RT/nF)ln Q. At 25°C: E = E° − (0.0592/n)log Q. At equilibrium (Q = K): E = 0 and ΔG = 0, giving: E° = (RT/nF)ln K. The Nernst equation shows that electrode potential depends on temperature and concentrations of all ionic species.

Uses & Applications

The Nernst equation is used in: calculating electrode potentials at non-standard concentrations (e.g., pH glass electrode, ion-selective electrodes), deriving equilibrium constants from measured EMF, explaining the variation of battery voltage with state of charge, and in understanding the transmembrane potential of biological cells (Nernst potential for Na⁺, K⁺, Cl⁻).

Safety Information

No direct safety concern for the equation. The Nernst potential at biological membranes (typically −70 mV resting potential) is disrupted by toxins that alter ion channel permeability (local anaesthetics block Na⁺ channels; tetrodotoxin, saxitoxin block voltage-gated Na⁺ channels).

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Nernst Equation
Formula E = E° − (RT/nF)lnQ; at 25°C: E = E° − (0.0592/n)log Q
Synonyms Nernst equation, electrode potential equation, concentration cell formula

Frequently Asked Questions

An equation relating the electrode potential to the standard potential and the concentrations of reactants and products: E = E° - (RT/nF)ln(Q). At 25°C, this simplifies to E = E° - (0.0592/n)log(Q). Used to calculate cell potential under non-standard conditions.

More "N" Terms

View all "N" terms →
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z