Work out galvanic cell emf instantly with clear inputs, formula shown and shareable results.
Away from standard conditions a cell's voltage follows the Nernst equation, E = E0 - (RT/nF) ln Q. Diluting the products relative to the reactants pushes Q below one and raises the voltage. At 25 C the RT/nF factor is 0.02569/n volts, so a two-electron cell with Q = 0.01 gains about 59 mV over its standard potential.
Nernst equation
E = E0 - (RT / nF) x ln Q
Room-temperature form
E = E0 - (0.0592 / n) x log10 Q
Products build up, Q rises towards K, and the voltage falls. At Q = K the emf is zero and the battery is flat.
The RT/nF slope grows with temperature, so concentration effects on voltage are larger in a hot cell than a cold one.