Question

What does Nernstian mean with respect to potentiometry electrodes? Specifically the refernece electrode.

Answer 1

The potential of a potentiometric electrochemical cell is

Ecell = Ec − Ea

where E_c and E_a are reduction potentials for the redox reactions at the cathode and the anode. The reduction potentials are given by the Nernst equation

E = E^o − (RT / nF)lnQ

where E^o is the standard-state reduction potential, R is the gas constant, T is the temperature in Kelvins, n is the number of electrons in the redox reaction, F is Faraday’s constant, and Q is the reaction quotient. At a temperature of 298 K (25^oC) the Nernst equation is   

E = E^o − (0.05916 / n)logQ