General Chemistry • Electrochemistry
Select the cathode and anode standard reduction half-reactions, then enter the temperature and the activities (concentrations and gas pressures) of all relevant species. The calculator balances the overall cell reaction, constructs the reaction quotient \(Q\), and applies the Nernst equation \(E_\text{cell} = E_\text{cell}^{\circ} - \dfrac{RT}{nF}\ln Q\) to find the cell potential under the specified nonstandard conditions.
Use the Nernst equation Ecell = E°cell - (R*T/(n*F)) ln(Q). E°cell comes from the selected standard reduction potentials and Q is built from activities of reactants and products in the balanced overall reaction.
Choose the cathode and anode half-reactions from a standard reduction potential table, then compute E°cell = E°cathode - E°anode. The anode half-reaction is reversed for oxidation, but its listed value used in the subtraction is still its reduction potential.
Include only species whose activities can change, using products over reactants with stoichiometric powers. Pure solids and pure liquids are omitted because their activity is taken as 1, and electrons never appear in Q.
The term (R*T/(n*F)) requires absolute temperature, so T must be in kelvin to keep units consistent. Using Celsius directly gives an incorrect Nernst correction and wrong Ecell.
No. Standard potentials are intensive, so scaling half-reactions to match electrons does not change E° values; only the coefficients and the electron count n change.