Cell notation

Cell notation in chemistry is a shorthand way of expressing a certain reaction in an electrochemical cell.

The cell anode and cathode (half-cells) are separated by two bars or slashes representing a salt bridge, with the anode on the left and cathode on the right. Individual solid, liquid or aqueous phases within each half-cell are separated by a single bar. Concentrations of dissolved species, in each phase written in parentheses and the state of each phase (usually s, l, g or aq.) is included in a subscript after the species name.

Example: A cell defined by the following half reactions, with 0.010M CdCl2. The mercury does nothing except act as an amalgam.

AgCl(s) + e- --> Ag(s) + Cl-(aq) E = 0.222V

Cd2+(aq) + 2e- --> Cd(s) E = -0.403V

Cd(s), Hg(s) | CdCl2(aq)(0.010M) || AgCl(s) | Ag(s) E = 0.7585V

Note: This cell has a nonstandard potential due to the concentration (0.010M) and the mean activity coefficient (0.513).