Potassium dichromate

Potassium dichromate. It has the chemical formula K ₂ Cr ₂ O ₇ is a salt of the hypothetical dichromic acid (this acid is not stable in substance) H ₂ Cr ₂ O ₇ . It is a substance with an intense orange color. It is a strong oxidant.

Table of Contents

Summary

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1 Features
2 Synonyms used for naming
3 Physical properties
4 Chemical properties
5 How to obtain
6 Application
7 Management
- 1 Risks
8 Sources

characteristics

Chemical Formula: K ₂Cr ₂ O ₇
Composition: Cr: 35.36%; K: 26.58% and O: 38.07%.
Molecular Weight: 294.21 g / mol

Synonyms used for naming

Potassium Bichromate
Dipotassium salt of chromic acid

Physical properties

Aggregation Status :: Solid
Appearance :: Deep orange
Molar mass: 294.18 g / mol
Melting point: 671.15 K (398 ° C)
Boiling point: 773.15 K (500 ° C)
Density (at 25 0C with respect to water at 4 0C): 2,676
Heat of fusion: 29.8 cal / g
Dissolution heat: -62.5 cal / g
Solubility: soluble in water: a solution saturated at 0 0C contains 4.3%; at 20 0C, 11.7%; at 40 0C, 20.9%; at 60 oC, 31.3%; at 80 oC, 42% and at 100 oC, 50.2%.
A 1% aqueous solution has a pH of 4.04 and a 10% pH of 3.57.

Chemical properties

Dichromate potassium reacts violently with sulfuric acid and acetone or hydrazide.
With hydroxylamine, it reacts explosively and with ethylene glycol at 100 ° C, exothermic reaction .
Mixtures of this compound with metallic iron, metallic tungsten, and boron are pyrotechnic.
In general, it is incompatible with reducing agents, organic materials and with combustible materials that are found as small particles, since there can be ignition.

How to obtain

It is obtained by means of potassium chloride and sodium dichromate and by roasting of chromite and potassium carbonate at a temperature between 900 and 1000 0C.

It can also be obtained by exchanging the cation from sodium dichromate and potassium chloride.

Application

Potassium dichromate has a wide variety of uses, among which you can find:

It is used in the production of pyrotechnic and explosive products.
Potassium dichromate is used in electroplating to chrome other metals
As colorants.
In products for Printing.
For leather tanning.
In the manufacture of water repellent fabrics.
In the manufacture of electric bacteria.
Manufacture of other organic chemicals.
In the development of safety matches.
As a corrosion inhibitor.
In laboratories as an analytical reagent.
In the ceramic industry.
In obtaining pigments

Driving

Personal Protective Equipment: A gown, safety glasses and gloves should be used to handle this product in a well ventilated area.
Caution: Do not wear contact lenses when working with this product.
When transferring solutions of this compound, use a pipette, NEVER ASPIRE WITH THE MOUTH.

Risks

Fire and Explosion Hazards: This product is not flammable, but may cause fire upon contact with combustible materials. Decomposes generating oxygen
Health risks: The main problem of this product is its ability to corrode and irritate skin, eyes, mucous membranes and respiratory tract, as well as liver and kidneys , making it dangerous inhaled, ingested or in contact with skin.
Toxic effects of this product have been reported on the circulatory and central nervous systems, lungs, heart, kidneys, and gastrointestinal tract of rabbits exposed to chronic concentrations.
In general, the symptoms of poisoning from exposure to this compound are: burning sensation, cough, short breaths, headache, nausea, vomiting. In addition, erosion and discoloration of the teeth, nephritis and inflammation and ulceration of the gastrointestinal tract may occur.
Inhalation: Initially, it causes ulceration of the nose, then spasms, inflammation and edema of the larynx and bronchi, generating chemical pneumonitis and pulmonary edema, which ultimately causes death.
Eye contact: Causes serious burns.
Skin contact: Constant use of this product without proper protection causes irritation, inflammation, ulcerations and, finally, dermatitis. Skin contact with large concentrations of chromates has been reported to cause kidney disorders, with no cases of cancer being found.
Ingestion: The effects of acute poisoning are: dental discoloration, nausea, vomiting, diarrhea and cardiovascular shock due to blood loss from the gastrointestinal tract.
On the other hand, in the case of very high doses (1.5-10 g), acute gastroenteritis, hematopoiesis, edema of the brain and lungs and damage to the liver and kidneys occur, ultimately causing death.
There have also been cases of poisoning by ingesting small doses (25 ppm) of chromates from contaminated water.
Carcinogenicity: This product has been linked to lung cancer and is considered a carcinogen in various documents. However, studies on laboratory animals have not demonstrated the carcinogenicity of calcium chromate and other related insoluble compounds.
Mutagenicity: Causes chromosomal aberrations and increases the frequency of sister chromatid exchange in mammalian cell cultures. Positive results were also obtained in tests with Bacillus Subtilis.
Reproductive Hazards: A high incidence of complications has been reported in pregnant women involved with the management of potassium dichromate and this product has been found within the placenta and breast milk.