Silver sulfide
| Names | |
|---|---|
| IUPAC name
Silver(I) sulfide | |
| Other names
Silver sulfide Argentous sulfide | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.040.384 |
| EC Number |
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PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| Ag2S | |
| Molar mass | 247.80 g·mol−1 |
| Appearance | Grayish-blackish crystal |
| Odor | Odorless |
| Density | 7.234 g/cm3 (25 °C) 7.12 g/cm3 (117 °C) |
| Melting point | 836 °C (1,537 °F; 1,109 K) |
| 6.21·10−15 g/L (25 °C) | |
Solubility product (Ksp) |
6.31·10−50 |
| Solubility | Soluble in aq. HCN, aq. citric acid with KNO3 Insoluble in acids, alkalies, aqueous ammoniums |
| Structure | |
| Monoclinic, mP12 (α-form) Cubic, cI8 (β-form) Cubic, cF12 (γ-form) | |
| Im3m, No. 229 (α-form) P21/n, No. 14 (β-form) Fm3m, No. 225 (γ-form) | |
| 2/m (α-form) 4/m 3 2/m (β-form, γ-form) | |
a = 4.23 Å, b = 6.91 Å, c = 7.87 Å (α-form) α = 90°, β = 99.583°, γ = 90° | |
| Thermochemistry | |
Heat capacity (C) |
76.57 J/mol·K |
Std molar entropy (S⦵298) |
143.93 J/mol·K |
Std enthalpy of formation (ΔfH⦵298) |
−32.59 kJ/mol |
Gibbs free energy (ΔfG⦵) |
−40.71 kJ/mol |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards |
May cause irritation |
| GHS labelling: | |
| Warning | |
| H315, H319, H335 | |
| P261, P305+P351+P338 | |
| NFPA 704 (fire diamond) | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |
Silver sulfide is an inorganic compound with the formula Ag
2S. A dense black solid, it is the only sulfide of silver. It is useful as a photosensitizer in photography. It constitutes the tarnish that forms over time on silverware and other silver objects. Silver sulfide is insoluble in most solvents, but is degraded by strong acids. Silver sulfide is a network solid made up of silver (electronegativity of 1.98) and sulfur (electronegativity of 2.58) where the bonds have low ionic character (approximately 10%).