Silver oxide explained

Silver oxide is the chemical compound with the formula Ag₂O. It is a fine black or dark brown powder that is used to prepare other silver compounds.

Preparation

Silver oxide can be prepared by combining aqueous solutions of silver nitrate and an alkali hydroxide.^[1] This reaction does not afford appreciable amounts of silver hydroxide due to the favorable energetics for the following reaction:^[2]

2 AgOH -> Ag2O + H2O (pK = 2.875^[3])With suitably controlled conditions, this reaction can be used to prepare Ag₂O powder with properties suitable for several uses including as a fine grained conductive paste filler.^[4]

Structure and properties

Ag₂O features linear, two-coordinate Ag centers linked by tetrahedral oxides. It is isostructural with Cu₂O. It "dissolves" in solvents that degrade it. It is slightly soluble in water due to the formation of the ion and possibly related hydrolysis products.^[5] It is soluble in ammonia solution, producing active compound of Tollens' reagent. A slurry of Ag₂O is readily attacked by acids:

Ag2O + 2 HX -> 2 AgX + H2Owhere HX = HF, HCl, HBr, HI, or CF₃COOH. It will also react with solutions of alkali chlorides to precipitate silver chloride, leaving a solution of the corresponding alkali hydroxide.^{[5] [6]}

Despite the photosensitivity of many silver compounds, silver oxide is not photosensitive,^[7] although it readily decomposes at temperatures above 280 °C.^[8]

Applications

This oxide is used in silver-oxide batteries. ^[9] In organic chemistry, silver oxide is used as a mild oxidizing agent. ^[10] For example, it oxidizes aldehydes to carboxylic acids.^[11]

External links

• Annealing of Silver Oxide – Demonstration experiment: Instruction and video

Notes and References

1. O. Glemser and H. Sauer "Silver Oxide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1037.
2. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. .
3. 10.3891/acta.chem.scand.14-0717 . Biedermann, George . Sillén, Lars Gunnar . Studies on the Hydrolysis of Metal Ions. Part 30. A Critical Survey of the Solubility Equilibria of Ag₂O . 1960 . Acta Chemica Scandinavica . 13 . 717–725. free .
4. US. 20050050990A1. Fine-grain silver oxide powder. 2005-03-10. Harigae. Shoji. Kenichi. Yoshiyuki.
5. Book: Cotton, F. Albert . Geoffrey Wilkinson . Wilkinson, Geoffrey . Advanced Inorganic Chemistry (2nd Ed.) . New York:Interscience . 1042. 1966. F. Albert Cotton .
6. General Chemistry by Linus Pauling, 1970 Dover ed. p703-704
7. Herley. P. J.. Prout. E. G.. 1960-04-01. The Thermal Decomposition of Silver Oxide. Journal of the American Chemical Society. 82. 7. 1540–1543. 10.1021/ja01492a006. 0002-7863.
8. http://themerckindex.cambridgesoft.com/TheMerckIndex/default.asp?formgroup=basenp_form_group&dataaction=db&dbname=TheMerckIndex Merck Index of Chemicals and Drugs
9. Web site: 2009-12-20 . Duracell PROCELL: The Chemistries: Silver Oxide . 2024-05-12 . web.archive.org.
10. Book: 裴, 坚 . 基础有机化学 . 4th . 2017 . 1064 . Chinese . Basic Organic Chemistry.
11. Chakraborty . Debashis . Gowda . Ravikumar R. . Malik . Payal . 2009 . Silver nitrate-catalyzed oxidation of aldehydes to carboxylic acids by H2O2 . Tetrahedron Letters . en . 50 . 47 . 6553–6556 . 10.1016/j.tetlet.2009.09.044.