terminal of the electrometer connected to the working electrode and the negative terminal to the reference electrode. Sign conventions Historically, two conventions for sign for the electrode potential have formed: convention "Nernst–Lewis–Latimer" (sometimes referred to as "American"), convention "Gibbs–Ostwald–Stockholm" (sometimes referred to as "European"). In 1953 in Stockholm IUPAC recognized that either of the conventions is permissible; however, it unanimously recommended that only the magnitude expressed according to the convention (2) be called "the electrode potential". To avoid possible ambiguities, the electrode potential thus defined can also be referred to as Gibbs–Stockholm electrode potential. In both conventions, the standard hydrogen electrode is defined to have a potential of 0 V. Both conventions also agree on the sign of for a half-cell reaction when it is written as a reduction. The main difference between the two conventions is that upon reversing the direction of a half-cell reaction as written, according to the convention (1) the sign of also switches, whereas in the convention (2) it does not. The logic behind switching the sign of is to maintain the correct sign relationship with the Gibbs free energy change, given by where is the number of electrons involved and is the Faraday constant. It is assumed that the half-reaction is balanced by the appropriate SHE half-reaction. Since switches sign when a reaction is written in reverse, so too, proponents of the convention (1) argue, should the sign of . Proponents of the convention (2) argue that all reported electrode potentials should be consistent with the electrostatic sign of the relative potential difference. Potential difference of a cell assembled of two electrodes Potential of a cell assembled of two electrodes can be determined from the two individual electrode potentials using or, equivalently, This follows from the IUPAC definition of the electric potential difference of a galvanic cell, according to which the electric potential difference of a cell is the difference of the potentials of the electrodes on the right and the left of the galvanic cell. When is positive, then positive electrical charge flows through the cell from the left electrode (anode) to the right electrode (cathode). See also Absolute electrode potential Electric potential Galvani potential Nernst equation Overpotential Potential difference (voltage) Standard electrode potential Table of standard electrode potentials Thermodynamic activity Volta potential References Electrochemistry Electrochemical potentials