Silver chromate
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Silver chromate is an inorganic compound with formula Ag2CrO4 which appears as distinctively coloured brown-red crystals. The compound is insoluble and its precipitation is indicative of the reaction between soluble chromate and silver precursor salts (commonly potassium/sodium chromate with silver nitrate).[5][7][8] This reaction is important for two uses in the laboratory: in analytical chemistry it constitutes the basis for the Mohr method of argentometry,[9] whereas in neuroscience it is used in the Golgi method of staining neurons for microscopy.[10]
Names | |
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IUPAC name
Silver chromate | |
Other names
Silver chromate(VI) Silver(I) chromate | |
Identifiers | |
3D model (JSmol) |
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ChemSpider |
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ECHA InfoCard | 100.029.130 |
EC Number |
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PubChem CID |
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UNII | |
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Properties | |
Ag2CrO4 | |
Molar mass | 331.73 g/mol |
Appearance | brick-red powder[1] |
Density | 5.625 g/cm3[1] |
Melting point | 665 °C (1,229 °F; 938 K) |
Boiling point | 1,550 °C (2,820 °F; 1,820 K) |
0.14 mg/L (0 °C)[1] | |
Solubility product (Ksp) |
1.12×10−12[2] |
Solubility | soluble in nitric acid, ammonia, alkali cyanides and chromates[3] |
UV-vis (λmax) | 450 nm (22200 cm−1) |
−40.0·10−6 cm3/mol[4] | |
Refractive index (nD) |
2.2 (630 nm) |
Structure[5] | |
orthorhombic (T<482 °C) hexagonal (T>482 °C) | |
Pnma, № 62 (low T form) | |
a = 10.063 Å, b = 7.029 Å, c = 5.540 Å | |
Formula units (Z) |
4 |
Thermochemistry[6] | |
Heat capacity (C) |
142.3 J·mol−1·K−1 |
Std molar entropy (S⦵298) |
217.6 J·mol−1·K−1 |
Std enthalpy of formation (ΔfH⦵298) |
−731.7 kJ·mol−1 |
Gibbs free energy (ΔfG⦵) |
−641.8 kJ·mol−1 |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards |
carcinogenic, oxidiser, environmental hazard |
GHS labelling: | |
Danger | |
H272, H317, H350, H410 | |
P201, P210, P273, P280, P302+P353, P308+P313 | |
Related compounds | |
Other anions |
Silver nitrate Silver chloride Silver thiocyanate |
Other cations |
Potassium chromate Ammonium chromate Lead(II) chromate |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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In addition to the above, the compound has been tested as a photocatalyst for wastewater treatment.[7] The most important practical and commercial application for silver chromate, however, is its use in Li-Ag2CrO4 batteries, a type of lithium battery mainly found in artificial pacemaker devices.[11]
As for all chromates, which are chromium(VI) species, the compound poses a hazard of toxicity, carcinogenicity and genotoxicity, as well as great environmental harm.