Silver oxide


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. This reaction does not afford appreciable amounts of silver hydroxide due to the favorable energetics for the following reaction:
US patent 20050050990 describes the preparation of Ag2O with properties suitable for use as a fine grained conductive paste filler.

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 Ag2− and possibly related hydrolysis products. It is soluble in ammonia solution, producing active compound of Tollens' reagent.
A slurry of Ag2O is readily attacked by acids:
where HX = HF, HCl, HBr, or HI, HO-C-CF3. 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 silver-oxide batteries. 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.