The Nernst equation indicates the electrochemical potential that arises from the concentration differences between 2 otherwise identical solutions in an electrochemical cell or separated by a semipermeable membrane.
electrical potential in volts =
= ((-1) * (gas constant) * (temperature in °K) / ((number of mole electrons ) * (Farraday constant))) * ln ((concentration of cation on side 1) / (concentration of cation on side 2)) =
= ((-1) * (1.9872) * (273.16 + (temperature in °C)) / ((valence of cation) * (23060))) * ln (ratio of cation concentrations)
Constants
Values
0°C
273.15 °K
Faraday constant
96,486 coulombs
23,060 cal/volt
gas constant (R)
1.9872 cal / mol•deg
0.08205 liter•atm / mol•deg
1 cal
4.184 joules
0.04129 liter•atm
For a monovalent cation at 37° C:
electrical potential in millivolts =
= (- 26.73) * ln (ratio of cation concentrations)
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