Electrode potential

It may also be defined as the potential difference between the charged metallic rods and salt solution.

It is common, for instance, to speak of the electrode potential of the M+/M redox couple.

An operational assumption for determinations of the electrode potentials with the standard hydrogen electrode involves this reference electrode with hydrogen ion in an ideal solution having is "zero potential at all temperatures" equivalently to standard enthalpy of formation of hydrogen ion is also "zero at all temperatures".

The measurement is generally conducted using a three-electrode setup (see the drawing): In case of non-zero net current on the electrode, it is essential to minimize the ohmic IR-drop in the electrolyte, e.g., by positioning the reference electrode near the surface of the working electrode (e.g., see Luggin capillary), or by using a supporting electrolyte of sufficiently high conductivity.

The logic behind switching the sign of E is to maintain the correct sign relationship with the Gibbs free energy change, given by ΔG = –nFE where n is the number of electrons involved and F is the Faraday constant.