Electrode Potential

The electrode potential (pE) is the negative base-10 log of electron activity (e-):

pE = -log(e-)

It is a dimensionless quantity that measures the tendency of a chemical system to exchange electrons or undergo redox reactions. It is negative in a reducing medium and positive in an oxidizing medium. pE and Eh are related:

Eh = 2.303RT/F * pE

Where:
F is Faraday’s Constant (96.5 kJ V^-1)
R is the gas constant (8.3 x 10^-3 kJ K^-1 mole^-1); and
T is temperature measured in Kelvin (K)