Conditional (formal) potential,

,is related to the
potential of a cell reaction,

, by an equation analogous to that relating

to the standard potential

, with the activity,

, replaced by any composition
variable,

(to be indicated by a subscript). For example:
Source:
Cite as:
IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by
A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).
XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic,
J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8.
https://doi.org/10.1351/goldbook.