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Silver(I) oxide

Silver oxide
Silver(I) oxide structure in unit cell
Silver(I) oxide powder
Names
IUPAC name
Silver(I) oxide
Other names
Silver rust, Argentous oxide, Silver monoxide
Identifiers
3D model (Jmol)
ChemSpider
ECHA InfoCard 100.039.946
EC Number 243-957-1
MeSH silver+oxide
PubChem CID
RTECS number VW4900000
Properties
Ag2O
Molar mass 231.74 g·mol−1
Appearance Black/ brown cubic crystals
Odor Odorless
Density 7.14 g/cm3
Melting point 300 °C (572 °F; 573 K) decomposes from ≥200 °C
0.013 g/L (20 °C)
0.025 g/L (25 °C)
0.053 g/L (80 °C)
Solubility product (Ksp) of AgOH
 1.52·10−8 (20 °C)
Solubility Soluble in acid, alkali
Insoluble in ethanol
−134.0·10−6 cm3/mol
Structure
Cubic
Pn3m, 224
Thermochemistry
65.9 J/mol·K
122 J/mol·K
−31 kJ/mol
−11.3 kJ/mol
Hazards
GHS pictograms The flame-over-circle pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word Danger
H272, H315, H319, H335
P220, P261, P305+351+338
Oxidizing Agent O Irritant Xi
R-phrases R36/37/38
S-phrases S17, S26, S36
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Lethal dose or concentration (LD, LC):
LD50 (median dose)
 2.82 g/kg (rats, oral)
Related compounds
Related compounds
 Silver(I,III) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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.

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.

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 Ag(OH)2− and possibly related hydrolysis products. It dissolves in ammonia solution to give soluble derivatives. A slurry of Ag2O is readily attacked by acids:

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.

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.


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