Silver phosphate or silver orthophosphate is a light sensitive, yellow, water-insoluble chemical compound composed of silver and phosphate ions of formula Ag3PO4.
Synthesis, reactions and properties
Silver phosphate is formed as a yellow solid precipitate by the reaction between a soluble silver salt, such as silver nitrate, with a soluble orthophosphate. Its solubility product is 8.89×10−17 mol4·dm−2. The precipitation reaction is analytically significant and can be used in qualitative or quantitative analysis.
This compound dissolves in aqueous ammonia. Large crystals of silver phosphate form upon gradual evaporation of such ammoniacal solutions.
The precipitation of silver phosphate is useful in traditional analytical chemistry. Precipitation of silver phosphate is also used in silver staining of biological materials (after reduction to silver metal) - as a magnifying agent for phosphate.
Silver phosphate also found use in early photography as a light sensitive agent.
Silver pyrophosphate Ag4P2O7 (CAS No. 13465-97-9) can be prepared as a white precipitate from reaction of silver(I) and pyrophosphate ions. Like silver orthophosphate it is light sensitive. Silver orthophosphate turns red on exposure to light. It has a density of 5.306 g/cm3 and a melting point of 585°C. A hydrate also exists which decomposes at 110°C.
Silver metaphosphate (AgPO3) (CAS No. 13465-96-8) is a white solid with a density of 6.370 g/cm3 and a melting point of 482°C. A hydrate also exists which decomposes at 240°C.
References
↑Weast, Robert C., ed. (1981). CRC Handbook of Chemistry and Physics (62nded.). Boca Raton, Florida: CRC Press. p.B-145. ISBN0-8493-0462-8..
↑John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99ed.). CRC Press. pp.5–189. ISBN978-1138561632.
↑Inorganic chemistry, Egon Wiberg, Nils Wiberg, Arnold Frederick Holleman, Academic Press, 2001 p.721 Google Books excerpt
↑F.H. Firsching (1961). "Precipitation of Silver Phosphate from Homogenous Solution". Anal. Chem.33 (7): 873–874. doi:10.1021/ac60175a018.
↑R. Masse, I, Tordjman, A. Durif (1976). "Affinement de la Structure Cristalline du Monophosphate d'Argent Ag3PO4. Existence d'une Forme Haute Témperature". Zeitschrift für Kristallographie. 144 (1–6): 76–81. Bibcode:1976ZK....144...76M. doi:10.1524/zkri.1976.144.1-6.76.{{cite journal}}: CS1 maint: multiple names: authors list (link)
↑Silver CompoundsArchived 2013-12-03 at the Wayback Machine p.5, section 2.22, from Kirk-Othmer Encyclopedia of Chemical Technology, Authors: SAMUEL F. ETRIS (The Silver Institute), C. ROBERT CAPPEL (Eastman Kodak Company), via www.scribd.com
123Bulletin of the National Research Council, National Research Council (U.S.A), 1950, pp.56-57 google books link