| Silver oxide | |
|---|---|
-oxide-sample.jpg) |
|
| IUPAC name |
Silver(I) oxide
|
| Other names | Silver rust, Argentous oxide |
| Identifiers | |
| CAS number | 20667-12-3  |
| Properties | |
| Molecular formula | Ag2O |
| Molar mass | 231.735 g/mol |
| Appearance | black/brown cubic crystals |
| Density | 7.14 g/cm3 |
| Melting point |
280°C (decomposition) |
| Solubility in water | 0.0025 g/100 ml[1] |
| Solubility product, Ksp of AgOH | 1.52 × 10-8 (20°C) |
| Solubility | soluble in acid, alkali insoluble in alcohol, ethanol [2] |
| Structure | |
| Crystal structure | cubic |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
-31.1 kJ·mol-1 |
| Standard molar entropy S |
121.3 J·mol-1·K-1 |
| Specific heat capacity, C | 65.9 J·mol-1·K-1[3] |
| Hazards | |
| MSDS | Material Safety Data Sheet |
| Related compounds | |
| Related compounds | silver(I,III) oxide, AgO |
| (what is this?) (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
| 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.
Contents |
Preparation
Silver oxide is commercially available. It can be easily prepared by combining aqueous solutions of silver nitrate and an alkali hydroxide.[4] Noteworthy is the fact that this reaction does not afford appreciable amounts of silver hydroxide due to the favorable energetics for the following reaction:[5]
Properties
Like most binary oxides, Ag2O is a three-dimensional polymer with covalent metal-oxygen bonding. It is therefore expected that Ag2O is insoluble in all solvents,[7] 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.[8] It hydrolyzes only slightly in water (1 part in 40,000) and dissolves in ammonium hydroxide 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.[9][8]
Like many silver compounds, silver oxide is photosensitive. It also decomposes at temperatures above 280 °C.[7]
Applications
Silver oxide is used in a silver-oxide battery. Silver oxide reacts easily with ligand precursors such as 1,3-disubstituted imidazolium or benzimidazolium salts to generate the corresponding N-heterocyclic carbene complexes. These silver complexes are useful as carbene-transfer agents, easily displacing labile ligands such as cyclooctadiene or acetonitrile. This is a common way of synthesizing transition metal carbene complexes.[10]
References
- ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 4-83, ISBN 0849305942
- ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
- ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 5-5, ISBN 0849305942
- ^ Janssen, D. E.; Wilson, C. V. (1963), "4-Iodoveratrole", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV4P0547; Coll. Vol. 4: 547
- ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ 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:.
- ^ a b Merck Index of Chemicals and Drugs, 14th ed. monograph 8521
- ^ a b Cotton, F. Albert; Wilkinson, Geoffrey (1966). Advanced Inorganic Chemistry (2nd Ed.). New York:Interscience. Advanced Inorganic Chemistry by Cotton and Wilkinson, 2nd ed. p1042
- ^ General Chemistry by Linus Pauling, 1970 Dover ed. p703-704
- ^ Wang, H. M. J.; Lin, I. J. B. (1998). "Facile Synthesis of Silver(I)-Carbene Complexes. Useful Carbene Transfer Agents". Organometallics 17: 972-975. doi:.
External links
- Annealing of Silver Oxide Demonstration experiment: Instruction and video
- Silver Oxide, Ag2O
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