Silver(I) 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. This reaction does not afford appreciable amounts of silver hydroxide due to the favorable energetics for the following reaction:
- 2 AgOH â†' Ag2O + H2O (pK = 2.875)
US patent 20050050990 describes the preparation of AgO with properties suitable for use as a fine grained conductive paste filler.
Structure and properties
Ag2O is isostructural with Cu2O. It is therefore expected that Ag2O is insoluble in all solvents, except by reaction. It is slightly soluble in water due to the formation of the ion Ag(OH)2âˆ' and possibly related hydrolysis products. It dissolves in ammonia solution to give soluble derivatives. A slurry of Ag2O is readily attacked by acids:
- Ag2O + 2 HX â†' 2 AgX + H2O
where HX = HF, HCl, HBr, or HI, HO2CCF3. It will also react with solutions of alkali chlorides to precipitate silver chloride, leaving a solution of the corresponding alkali hydroxide.
Like many silver compounds, silver oxide is photosensitive. It also decomposes at temperatures above 280 °C.
Applications
This oxide is used in some silver-oxide batteries, as is the silver(I,III)oxide, Ag4O4. In organic chemistry, silver oxide is used as a mild oxidizing agent. For example, it oxidizes aldehydes to carboxylic acids. Such reactions often work best when the silver oxide is prepared in situ from silver nitrate and alkali hydroxide.
References
External links
- Annealing of Silver Oxide Demonstration experiment: Instruction and video
- Silver Oxide, Ag2O
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