Potassium chromate

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Potassium chromate
Potassium-chromate-sample.jpg
Potassium chromate.svg
Identifiers
CAS number7789-00-6 YesY
PubChem24597
ChemSpider22999 N
EC number232-140-5
ChEBICHEBI:75249 N
RTECS numberGB2940000
Jmol-3D imagesImage 1
Properties
Molecular formulaCrK2O4
Molar mass194.19 g mol−1
AppearanceYellow powder
Odorodorless
Density2.7320 g/cm3
Melting point968 °C (1,774 °F; 1,241 K)
Boiling point1,000 °C (1,830 °F; 1,270 K)
Solubility in water62.9 g/100 mL (20 °C)

75.1 g/100 mL (80 °C)
79.2 g/100 mL (100 °C)
Solubilityinsoluble in alcohol
Refractive index (nD)1.74
Structure
Crystal structurerhombic
Hazards
MSDSChemical Safety Data
EU Index024-006-00-8
EU classificationCarc. Cat. 2
Muta. Cat. 2
Toxic (T)
Irritant (Xi)
Dangerous for the environment (N)
R-phrasesR49, R46, R36/37/38, R43, R50/53
S-phrasesS53, S45, S60, S61
NFPA 704
Related compounds
Other anionsPotassium dichromate
Potassium molybdate
Potassium tungstate
Other cationsSodium chromate
Calcium chromate
Barium chromate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references
 
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Not to be confused with Potassium dichromate.
Potassium chromate
Potassium-chromate-sample.jpg
Potassium chromate.svg
Identifiers
CAS number7789-00-6 YesY
PubChem24597
ChemSpider22999 N
EC number232-140-5
ChEBICHEBI:75249 N
RTECS numberGB2940000
Jmol-3D imagesImage 1
Properties
Molecular formulaCrK2O4
Molar mass194.19 g mol−1
AppearanceYellow powder
Odorodorless
Density2.7320 g/cm3
Melting point968 °C (1,774 °F; 1,241 K)
Boiling point1,000 °C (1,830 °F; 1,270 K)
Solubility in water62.9 g/100 mL (20 °C)

75.1 g/100 mL (80 °C)
79.2 g/100 mL (100 °C)
Solubilityinsoluble in alcohol
Refractive index (nD)1.74
Structure
Crystal structurerhombic
Hazards
MSDSChemical Safety Data
EU Index024-006-00-8
EU classificationCarc. Cat. 2
Muta. Cat. 2
Toxic (T)
Irritant (Xi)
Dangerous for the environment (N)
R-phrasesR49, R46, R36/37/38, R43, R50/53
S-phrasesS53, S45, S60, S61
NFPA 704
Related compounds
Other anionsPotassium dichromate
Potassium molybdate
Potassium tungstate
Other cationsSodium chromate
Calcium chromate
Barium chromate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Potassium chromate (K2CrO4) is a yellow chemical indicator used for identifying concentrations of chloride ions in a salt solution with silver nitrate (AgNO3). It is a class two carcinogen and can cause cancer on inhalation.[1]

General information[edit]

Physical properties[edit]

Potassium Chromate is a lemon-colored compound that is in the form of a crystalline solid, and it is very stable.[citation needed]

Production[edit]

It is prepared by roasting powdered chromite with potash and limestone, treating the cinder with a hot potassium sulfate solution and leaching.

Alternatively, it may be prepared by the reaction of potassium dichromate and potassium hydroxide.

Reactions[edit]

When reacted with lead(II) nitrate, it creates an orange-yellow precipitate, lead(II) chromate. All ions hydrolyze in solution[citation needed].

Applications[edit]

It is used as a mordant in dyeing fabrics, as a tanning agent in the leather industry, in bleach oils and waxes, and as an oxidizing agent in organic synthesis.

Occurrence[edit]

Tarapacaite is the natural, mineral form of potassium chromate. It occurs very rarely and until now is known from only few localities on Atacama desert.[citation needed]

Safety[edit]

Potassium chromate is very toxic and may be fatal if swallowed. It may also act as a carcinogen, and can create reproductive defects if inhaled or swallowed. It also is a strong oxidizing agent if in the presence of H+ to produce the dichromate ion. It may react rapidly, or violently. It is also possible that it may react explosively with other reducing agents and flammable objects.

References[edit]

  1. ^ Potassium chromate information URL last accessed 15 March 2007