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Silver oxide

Names
IUPAC name Silver(I) oxide
Other names Silver rust, Argentous oxide
Identifiers
CAS Number	20667-12-3
ECHA InfoCard	100.039.946
CompTox Dashboard (EPA)	DTXSID40893897
Properties
Chemical formula	Ag2O
Molar mass	231.735 g/mol
Appearance	black/brown cubic crystals
Density	7.14 g/cm
Melting point	280 °C
Solubility in water	0.025 g/L
Solubility product (Ksp) of AgOH	1.52×10 (20 °C)
Solubility	soluble in acid, alkali insoluble in alcohol, ethanol
Structure
Crystal structure	cubic
Thermochemistry
Heat capacity (C)	65.9 J·mol·K
Std molar entropy (S298)	121.3 J·mol·K
Std enthalpy of formation (ΔfH298)	-31.1 kJ·mol
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Y verify (what is  ?) 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.

Preparation

Silver oxide is commercially available. It can be easily prepared by combining aqueous solutions of silver nitrate and an alkali hydroxide. Noteworthy is the fact that this reaction does not afford appreciable amounts of silver hydroxide due to the favorable energetics for the following reaction:

2 AgOH → Ag₂O + H₂O (pK = 2.875)

Structure and properties

Like most binary oxides, Ag₂O is a three-dimensional polymer with covalent metal-oxygen bonding. It is isostructural with Cu₂O. It is therefore expected that Ag₂O is insoluble in all solvents, except by reaction. It is also slightly soluble in aqueous solution 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:

Ag₂O + 2 HX → 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

Commercially, silver oxide is used in a silver-oxide battery. 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

1. ^ Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 4–83. ISBN 0-8493-0594-2.
2. Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, FL: CRC Press. pp. 5–5. ISBN 0-8493-0594-2.
3. Janssen, D. E.; Wilson, C. V. (1963). "4-Iodoveratrole". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 4, p. 547.
4. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
5. Biedermann, George; Sillén, Lars Gunnar (1960). "Studies on the Hydrolysis of Metal Ions. Part 30. A Critical Survey of the Solubility Equilibria of Ag₂O". Acta Chemica Scandinavica. 14: 717. doi:10.3891/acta.chem.scand.14-0717.{{cite journal}}: CS1 maint: multiple names: authors list (link)
6. ^ Merck Index of Chemicals and Drugs, 14th ed. monograph 8521
7. ^ Cotton, F. Albert; Wilkinson, Geoffrey (1966). Advanced Inorganic Chemistry (2nd Ed.). New York:Interscience. p. 1042.{{cite book}}: CS1 maint: multiple names: authors list (link)
8. General Chemistry by Linus Pauling, 1970 Dover ed. p703-704

External links

• Annealing of Silver Oxide Demonstration experiment: Instruction and video
• Silver Oxide, Ag2O

• Silver compounds
• Oxides