Nernst Equation Calculator
Adjust standard electrode potentials for reaction quotient and temperature to predict real-world voltages.
Select log10 to reproduce the 0.05916/n factor at 298 K.
Cell potential
1.109 V
Nernst correction
-0.009 V
How to Use This Calculator
Start with a standard potential
Look up E0 for the half-cell or full cell reaction of interest at 298 K.
Determine the reaction quotient
Form Q using product activities divided by reactant activities raised to stoichiometric powers.
Enter electrons and temperature
Use the balanced reaction stoichiometry for n and convert temperature to Kelvin.
Choose logarithm base
Select natural log for the classic RT/nF form or log10 for the 0.05916/n shortcut at 298 K.
Formula
E = E0 - (RT / nF) ln(Q)
Alternatively, E = E0 - (2.303 RT / nF) log10(Q). At 298 K the factor becomes 0.05916/n for base 10 logarithms.
Example
Setting E0 = 1.10 V, Q = 0.5, n = 2, T = 298 K, and using log10 gives E = 1.10 - (0.05916/2) log10(0.5) = 1.11 V.
Full Description
The Nernst equation describes how electrode potentials shift when concentrations or pressures deviate from standard-state values. It is central to electrochemistry, corrosion studies, and biochemical redox reactions.
By adjusting for temperature and the reaction quotient, you can anticipate operating voltages, sensor responses, and equilibrium positions under realistic conditions.
Frequently Asked Questions
What units should Q use?
Use activity ratios. For dilute solutions, concentrations in mol/L are acceptable when divided by the standard-state value of 1 mol/L.
Can I use partial pressures?
Yes. Insert gas partial pressures in atmospheres (or bar) relative to the standard-state pressure of 1.
How does temperature affect the 0.05916 factor?
The factor equals 2.303 RT/F. Increase temperature and the magnitude grows proportionally.
What if Q is less than 1?
The logarithm becomes negative, so the correction is negative and the potential increases above the standard value.
Can I compute equilibrium constants?
Yes. Set E to zero and solve for K, giving log10(K) = (n E0 F) / (2.303 RT) when using base 10 logarithms.