Calcium chromate
| Names | |
|---|---|
| IUPAC name
Calcium chromate
| |
| Other names
C. I. Pigment Yellow 33
Calcium chromate (VI) Calcium Chrome Yellow Calcium dioxido-dioxo-chromium Calcium monochromate Gelbin Yellow Ultramarine | |
| Properties | |
| CaCrO4 | |
| Molar mass | 156.072 g/mol |
| Appearance | Yellow solid |
| Odor | Odorless |
| Density | 3.12 g/cm3 |
| Melting point | 2,710 °C (4,910 °F; 2,980 K) |
| Boiling point | Decomposes |
| anhydrous 4.5 g/100 ml (0 °C) 2.25 g/100 ml (20 °C) dihydrate 16.3 g/100ml (20 °C) 18.2 g/100ml (40 °C) | |
| Solubility | Reacts with strong acids Practically insoluble in alcohol |
| Vapor pressure | ~0 mmHg |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Flash point | Non-flammable |
| Lethal dose or concentration (LD, LC): | |
| LD50 (Median dose)
|
327 mg/kg (rat, oral) |
| Related compounds | |
| Related compounds
|
Potassium chromate Sodium chromate |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Calcium chromate is a bright yellow chemical compound, with the formula CaCrO4, often encountered as dihydrate.
Contents
Properties
Chemical
Calcium chromate reacts with sulfuric acid to release chromic acid or chromium trioxide, precipitating calcium sulfate.
Physical
Calcium chromate is a yellow solid, odorless, somewhat soluble in water.
Availability
Calcium chromate is sold by chemical suppliers, though in some countries, like EU states, its sale is restricted, as it is a hexavalent compound, which are classified as toxic and carcinogenic.
It can be found in nature in anhydrous form as the rare mineral chromatite, first identified in the arid areas on Israel.
Preparation
Can be prepared by adding calcium chloride to sodium or potassium chromate.
Projects
- Make chromium trioxide
Handling
Safety
Calcium chromate, like all hexavalent chromium compounds, is highly toxic and carcinogenic on ingestion or inhalation. Handling it without gloves can cause dermatitis, and can also be absorbed through the skin in small amounts, usually if wet. Aqueous solutions are notorious for staining most materials.
Always wear gloves and goggles when handling it, and a dust mask or respirator when handling it as a powder to avoid inhalation of it, which could be fatal.
Storage
Calcium chromate should be kept in closed bottles, with a proper label and a hazard symbol.
Disposal
Calcium chromate can be safely reduced to the less harmful Cr(III) oxide with a reducing agent, such as ascorbic acid, or potassium/sodium sulfites/metabisulfites/tiosulfates.
