Relation Between the SHE and the Internal Ag∕AgCl Reference Electrode at High Temperatures

Autor: S. Forsberg, J. Öijerholm, M. Ullberg, H. P. Hermansson
Rok vydání: 2009
Předmět:
Zdroj: Journal of The Electrochemical Society. 156:P56
ISSN: 0013-4651
Popis: This article reviews the electropotential relation between the internal Ag/AgCl reference electrode used in nuclear light water reactor (LWR) applications and the standard hydrogen electrode (SHE). The focus is on the formation of AgCl 1-n n complexes and how these might affect the potential of the Ag/AgCl electrode. In LWR applications the internal Ag/AgCl reference electrode is subjected to temperatures up to above 300°C, depending on reactor design. At temperatures of > 150°C, the solubility products governing the concentration of AgCl 1-n n complexes and thus the concentration of free Cl - in solution are different from what is known at room-temperature conditions. The potential of the Ag/AgCl electrode is in turn dependent on the concentration of free Cl - . Therefore, it is likely that also the potential of the reference electrode is altered, compared to the value derived by ignoring the formation of AgCl 1-n n complexes. The review is based partially on data from literature and partially on thermodynamic calculations. Thermodynamical calculations based on the revised Helgeson-Kirkham-Flowers model were used to derive the equilibrium concentration of free Cl - . The revised electropotential relation between the internal Ag/AgCl reference electrode and the SHE assigns the electrode a higher potential compared to currently used models.
Databáze: OpenAIRE