Contents

Silver oxide

This article is about silver(I) oxide. For the mixed-valence oxide, see Silver(I,III) oxide.

Silver oxide

Unit cell
Crystal packing
Names
IUPAC name Silver(I) oxide
Other names Silver rust, Argentous oxide, Silver monoxide
Identifiers
CAS Number	20667-12-3 Y
3D model (JSmol)	Interactive image
ChemSpider	7970393 N
ECHA InfoCard	100.039.946
EC Number	243-957-1
MeSH	silver+oxide
PubChem CID	9794626
RTECS number	VW4900000
UNII	897WUN6G6T Y
CompTox Dashboard (EPA)	DTXSID40893897
InChI InChI=1S/2Ag.O/q2*+1;-2 N Key: NDVLTYZPCACLMA-UHFFFAOYSA-N N InChI=1S/2Ag.O/q2*+1;-2 Key: NDVLTYZPCACLMA-UHFFFAOYSA-N
SMILES [O-2].[Ag+].[Ag+]
Properties
Chemical formula	Ag2O
Molar mass	231.735 g·mol−1
Appearance	Black/ brown cubic crystals
Odor	Odorless[1]
Density	7.14 g/cm3
Melting point	300 °C (572 °F; 573 K) decomposes from ≥200 °C[3][5]
Solubility in water	0.013 g/L (20 °C) 0.025 g/L (25 °C)[2] 0.053 g/L (80 °C)[3]
Solubility product (Ksp) of AgOH	1.52·10−8 (20 °C)
Solubility	Soluble in acid, alkali Insoluble in ethanol[2]
Acidity (pKa)	12.1 (estimated)[4]
Magnetic susceptibility (χ)	−134.0·10−6cm3/mol
Structure
Crystal structure	Cubic
Space group	Pn3m, 224
Thermochemistry
Heat capacity (C)	65.9 J/mol·K[2]
Std molar entropy (S⦵298)	122 J/mol·K[6]
Std enthalpy of formation (ΔfH⦵298)	−31 kJ/mol[6]
Gibbs free energy (ΔfG⦵)	−11.3 kJ/mol[5]
Hazards
GHS labelling:
Pictograms	[7]
Signal word	Danger
Hazard statements	H272, H315, H319, H335[7]
Precautionary statements	P220, P261, P305+P351+P338[7]
NFPA 704 (fire diamond)	[1] 2 0 1
Lethal dose or concentration (LD, LC):
LD50 (median dose)	2.82 g/kg (rats, oral)[1]
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). N verify (what is YN ?) Infobox references

Silver oxide is the chemical compound with the formulaAg₂O. It is a fine black or dark brown powder that is used to prepare other silver compounds.

Preparation[edit]

Silver oxide can be prepared by combining aqueous solutions of silver nitrate and an alkali hydroxide.^[8][9] This reaction does not afford appreciable amounts of silver hydroxide due to the favorable energetics for the following reaction:^[10]

${\displaystyle {\ce {2 AgOH -> Ag2O + H2O}}}$ (pK = 2.875^[11])

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.^[12]

Structure and properties[edit]

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.^[13] It is soluble in ammonia solution, producing active compound of Tollens' reagent. A slurry of Ag₂O is readily attacked by acids:

${\displaystyle {\ce {Ag2O + 2 HX -> 2 AgX + H2O}}}$

where 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.^[13][14]

Despite the photosensitivity of many silver compounds, silver oxide is not photosensitive,^[15] although it readily decomposes at temperatures above 280 °C.^[16]

Applications[edit]

This oxide is used in silver-oxide batteries. ^[17]In organic chemistry, silver oxide is used as a mild oxidizing agent. ^[18] For example, it oxidizes aldehydestocarboxylic acids.^[19]

References[edit]

External links[edit]

Wikimedia Commons has media related to Silver(I) oxide.

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