Ammonium chromate
| Names | |
|---|---|
| IUPAC name
Ammonium chromate
| |
| Other names
Ammonium chromate(IV)
Diammonium chromate Diazanium dioxido(dioxo)chromium | |
| Properties | |
| (NH4)2CrO4 | |
| Molar mass | 152.07 g/mol |
| Appearance | Yellow crystalline solid |
| Odor | Ammonia |
| Density | 1.90 g/cm3 |
| Melting point | 185 °C (365 °F; 458 K) (decomposes) |
| Boiling point | Decomposes |
| 24.8 g/100ml (0 °C) 37.36 g/100ml (25 °C) 45.3 g/100ml (40 °C) 70.06 g/100ml (75 °C) | |
| Solubility | Sparingly soluble in acetone, liq. ammonia, methanol Practically insoluble in ethanol, isopropanol |
| Thermochemistry | |
| Std molar
entropy (S |
657 J·K-1·mol-1 |
| Std enthalpy of
formation (ΔfH |
-1,163 kJ/mol |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Related compounds | |
| Related compounds
|
Potassium chromate |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Ammonium chromate is a salt with the formula (NH4)2CrO4.
Contents
Properties
Chemical
Ammonium chromate, like ammonium dichromate burns when ignited, creating a volcano-like effect.
Physical
Ammonium chromate is a yellow solid, soluble in water, sparingly soluble in organic solvents.
Availability
Can be purchased from chemical suppliers.
Preparation
Ammonium chromate can be made by mixing an equimolar quantities of ammonia and ammonium dichromate.
Adding chromium trioxide to an aq. solution of ammonia will yield ammonium chromate.[1]
Another route involves mixing ammonium perchlorate with sodium chromate. Ammonium chromate is less soluble than NaClO4 and will precipitate out of the solution.
Projects
- Make chromium(III) oxide
Handling
Safety
Ammonium chromate is flammable and extremely toxic. It is a known carcinogen. Wear proper protection, such as gloves and a mask.
Storage
Ammonium chromate should be stored in closed bottles, in well ventilated places, with a proper label and a hazard symbol. As it gives off ammonia over time, the bottle should be open periodically.
Disposal
Ammonium chromate can be neutralized with a reducing agent, such as ascorbic acid, glucose or sodium/potassium sulfite/metabisulfite/thiosulfate.
