E = E° − (0.0592/n) × log(Q) at 25 °C
The Nernst equation E = E° − (RT/nF)ln(Q) adjusts the standard cell potential for non-standard concentrations or pressures. At 25°C, it simplifies to E = E° − (0.0592/n)log(Q). When Q = 1, E = E° (standard conditions). As reaction proceeds, Q increases, E decreases, until at equilibrium Q = K and E = 0. The equation links electrochemistry to thermodynamics: ΔG = −nFE. Applications: calculating battery voltages under load, pH electrode measurements (the glass electrode follows Nernst behavior), concentration cells (where E° = 0 but E ≠ 0 due to concentration differences), and corrosion science. The Nernst equation underpins all potentiometric measurements and electroanalytical techniques.