Silver carbonate
Chemical compound
From Wikipedia, the free encyclopedia
Silver carbonate is the chemical compound with the formula Ag2CO3. This salt is yellow but typical samples are grayish due to the presence of elemental silver. It is poorly soluble in water, like most transition metal carbonates.
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| Names | |
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| IUPAC name
Silver(I) carbonate | |
| Other names
Argentous carbonate | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.007.811 |
| EC Number |
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| MeSH | silver+carbonate |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| Ag2CO3 | |
| Molar mass | 275.75 g/mol |
| Appearance | Pale yellow crystals |
| Odor | Odorless |
| Density | 6.077 g/cm3[1] |
| Melting point | 218 °C (424 °F; 491 K) decomposes from 120 °C[1][2] |
| 0.031 g/L (15 °C) 0.032 g/L (25 °C) 0.5 g/L (100 °C)[3] | |
Solubility product (Ksp) |
8.46·10−12[1] |
| Solubility | Insoluble in ethanol, liquid ammonia, acetates, acetone[4] |
| −80.9·10−6 cm3/mol[1] | |
| Structure | |
| Monoclinic, mP12 (295 K) Trigonal, hP36 (β-form, 453 K) Hexagonal, hP18 (α-form, 476 K)[5] | |
| P21/m, No. 11 (295 K) P31c, No. 159 (β-form, 453 K) P62m, No. 189 (α-form, 476 K)[5] | |
| 2/m (295 K) 3m (β-form, 453 K) 6m2 (α-form, 476 K)[5] | |
α = 90°, β = 91.9713(3)°, γ = 90° | |
| Thermochemistry | |
Heat capacity (C) |
112.3 J/mol·K[1] |
Std molar entropy (S⦵298) |
167.4 J/mol·K[1] |
Std enthalpy of formation (ΔfH⦵298) |
−505.8 kJ/mol[1] |
Gibbs free energy (ΔfG⦵) |
−436.8 kJ/mol[1][2] |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Inhalation hazards |
Irritant |
| GHS labelling:[6] | |
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| Danger | |
| H315, H319, H335 | |
| P261, P305+P351+P338 | |
| NFPA 704 (fire diamond) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
3.73 g/kg (mice, oral)[7] |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation and reactions
Silver carbonate can be prepared by combining aqueous solutions of sodium carbonate with a deficiency of silver nitrate.[8]
- 2 AgNO3(aq) + Na2CO3(aq) → Ag2CO3(s) + 2 NaNO3(aq)
Freshly prepared silver carbonate is colourless, but the solid quickly turns yellow.[9]
Silver carbonate reacts with ammonia to give the diamminesilver(I) ([Ag(NH3)2]+) complex ion. Like other diamminesilver(I) solutions, including Tollens' reagent, there is a possibility that explosive Silver nitride may precipitate out of the solution. Silver nitride was previously known as fulminating silver but due to confusions with silver fulminate it has been discontinued by the IUPAC.[10]
With hydrofluoric acid, it gives silver fluoride.
The thermal conversion of silver carbonate to silver metal proceeds via formation of silver oxide:[11]
- Ag2CO3 → Ag2O + CO2
- 2 Ag2O → 4 Ag + O2
Uses
The principal use of silver carbonate is for the production of silver powder for use in microelectronics. It is reduced with formaldehyde, producing silver free of alkali metals:[9]
- Ag2CO3 + CH2O → 2 Ag + 2 CO2 + H2
Organic synthesis
Silver carbonate is used as a reagent in organic synthesis.[12] In the Fétizon oxidation, silver carbonate on Celite[13] serves as an oxidising agent to form:
- aldehydes from primary alcohols,
- ketones from secondary alcohols,
- keto-alcohols from diols,
- and ketones from hydroxymethyl compounds.
In the Koenigs-Knorr reaction it is used to convert alkyl bromides to the methyl ethers. It is also employed to convert alkyl bromides into alcohols.[8] As a base, it has been used in the Wittig reaction.[14] and in C-H bond activation.[15]
