Potassium chlorochromate
 Nice crystals of KCrO3Cl
| |
| Names | |
|---|---|
| IUPAC name
Potassium chlorochromate
| |
| Other names
Peligot's salt
Potassium chlorochromate(VI) Potassium monochlorochromate Potassium trioxochlorochromate Potassium trioxochromium chloride | |
| Properties | |
| KCrO3Cl | |
| Molar mass | 174.5472 g/mol |
| Appearance | Light orange crystalline solid |
| Odor | Odorless |
| Density | 2.5228 g/cm3 |
| Melting point | 290–292 °C (554–558 °F; 563–565 K) (decomposes) |
| Boiling point | Decomposes |
| Soluble | |
| Solubility | Very soluble in acetone |
| Vapor pressure | ~0 mmHg |
| Hazards | |
| Safety data sheet | Fisher Scientific |
| Flash point | Non-flammable |
| 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 | |
Potassium chlorochromate is an inorganic compound with the formula KCrO3Cl.
It is sometimes called Péligot's salt, in recognition of its discoverer Eugène-Melchior Péligot.
Contents
Properties
Chemical
Addition of conc. hydrochloric acid to this compound will yield chromyl chloride.
When treated with 18-crown-6, it forms the lipophilic salt [K(18-crown-6]CrO3Cl.
Physical
Potassium chlorochromate is an odorless orange-ish solid, soluble in water and acetone, though it will slowly hydrolyze in the former if kept too long.
Availability
Potassium chlorochromate is sold by chemical suppliers.
Since it's a Cr(VI) compound, its sale may be restricted in the EU.
Preparation
Potassium chlorochromate was originally prepared by treating potassium dichromate with conc. hydrochloric acid:[1]
- K2CrO4 + 2 HCl → 2 KCrO3Cl + H2O
Because of the equilibrium reaction, the yield of this reaction never can be 100%. High yield is favored by increasing the concentration of the hydrochloric acid and also by increasing the concentration of potassium dichromate in the solution, such that more chlorochromate(VI) can be crystallized from the solution. As the salt is susceptible to hydrolysis, the solution must not be boiled to dryness not should the wet crystals be dried at high temperatures.
A water-free route involves the reaction of chromyl chloride with potassium chromate:[2]
- K2CrO4 + CrO2Cl2 → 2 KCrO3Cl
Projects
- Oxidizer in organic chemistry
Handling
Safety
Potassium chlorochromate is very toxic upon ingestion (may cause acute poisoning and kidney damage amongst other complications) and it's also irritant to the human skin (may cause eye burns, irritation, allergy, or ulceration), or lungs if inhaled.
Storage
Potassium chlorochromate can be stored in glass bottles, away from reducing agents and humidity.
Disposal
A reducing agent, like sodium thiosulfate, sulfite or metabisulfite can be used to safely reduce hexavalent chromium compounds to Cr(III), which is far less harmful.
References
- ↑ https://woelen.homescience.net/science/chem/exps/KCrO3Cl/index.html
- ↑ https://onlinelibrary.wiley.com/doi/abs/10.1002/9780470132333.ch64
