The potential/pH diagram of silver in aqueous ammonium salt solution

✍ Scribed by J.H. Sluyters; M.D. Wijnen; H.J. van den Hul

• Publisher: Elsevier Science
• Year: 1961
• Tongue: English
• Weight: 434 KB
• Volume: 5
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(61)87005-9

✦ Synopsis

The potential]pH diagram of silver in aqueous ammonium salt solution at 25°C has been calculated and verified experimentally.

Calculations were carried out on the basis of the standard potential of the silver/silver-ion couple, the dissociation constants of the silver mono-and di-ammonia complex, and the dissociation constant of the ammonium ion, the total silver and nitrogen content being kept constant. The calculated diagram was verified by measuring the potential of the silver electrode at pH values varying from 2 to 12.

The measured diagram agrees well with the calculated one; minor differences (up to 15 mV) occur only in the alkaline range.

The establishment of the potential is sufficiently rapid to record the entire diagram on a suitable pen-and-ink X/Y recorder within a few minutes. Accordingly, such a recording may serve well as a lecture demonstration on potential/pH diagrams.

R&urn&-Le diagramme tension-pH de I'argent en solution ammoniacale aqueuse a 25°C a Bte calcule et verifie exptrimentalement.

Le calcul a ete effect& a partir de la tension standard du couple Ag/Ag+et des constantes de dissociation de l'ion ammonium et des complexes de l'argent avec une ou deux molecules d'ammoniaque, les teneurs totales en argent et azote &ant maintenues constantes.

Le diagramme calcule a tte v&it% en mesurant la tension de I'electrode d'argent a des valeurs du pH comprises entre 2 et 12

Le diagramme mesure est en bon accord avec le calcul; des ditferences relativement faibles (jusqu'a 15 mV) ont 6th observkes settlement en milieu alcalin.