SciTech Connect

Title: ELECTROMOTIVE FORCE, EMF (CELLS)

ELECTROMOTIVE FORCE, EMF (CELLS) The voltage or electric potential difference across the terminals of a cell when no current is drawn from it. The emf of a cell is the sum of the electric potential differences (PDs) produced by a separation of charges (electrons or ions) that can occur at each phase boundary (or interface) in the cell. The magnitude of each PD depends on the chemical nature of the two contacting phases. Thus, at the interface between two different metals, some electrons will have moved from the metal with a higher free energy of electrons to the metal with a lower free energy of electrons. The resultant charge separation will produce a PD (just as charge separation produces a voltage across a capacitor) that, at equilibrium, exactly opposes further electron flow. Similarly, PDs can be produced when electrons partition across a metal/solution interface or metal/solid interface, and when ions partition across a solution/membrane/solution interface.
Authors: ;
Publication Date:
OSTI Identifier:OSTI ID: 760971
Report Number(s):BNL--65847; KC030101
R&D Project: AS002CSD; KC030101; TRN: AH200035%%46
DOE Contract Number:AC02-98CH10886
Resource Type:Miscellaneous
Resource Relation:Other Information: PBD: 16 Sep 1998; Related Information: In: Encyclopedia of Science and Technology, vp.
Research Org:Brookhaven National Lab., Upton, NY (US)
Sponsoring Org:USDOE Office of Energy Research (ER) (US)
Country of Publication:United States
Language:English
Subject: 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ELECTRIC POTENTIAL; ELECTROMOTIVE FORCE; FREE ENERGY; ELECTROLYTIC CELLS; ELECTRON TRANSFER