Potassium chromate

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To be distinguished from Potassium dichromate.
Potassium chromate
Potassium-chromate-sample.jpg
Potassium chromate.svg
Identifiers
CAS number 7789-00-6 YesY
PubChem 24597
ChemSpider 22999 N
EC number 232-140-5
ChEBI CHEBI:75249 N
RTECS number GB2940000
Jmol-3D images Image 1
Properties
Molecular formula CrK2O4
Molar mass 194.19 g mol−1
Appearance Yellow powder
Odor odorless
Density 2.7320 g/cm3
Melting point 968 °C (1,774 °F; 1,241 K)
Boiling point 1,000 °C (1,830 °F; 1,270 K)
Solubility in water 62.9 g/100 mL (20 °C)

75.1 g/100 mL (80 °C)
79.2 g/100 mL (100 °C)
Solubility insoluble in alcohol
Refractive index (nD) 1.74
Structure
Crystal structure rhombic
Hazards
MSDS Chemical Safety Data
EU Index 024-006-00-8
EU classification Carc. Cat. 2
Muta. Cat. 2
Toxic (T)
Irritant (Xi)
Dangerous for the environment (N)
R-phrases R49, R46, R36/37/38, R43, R50/53
S-phrases S53, S45, S60, S61
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazard OX: Oxidizer. E.g., potassium perchlorateNFPA 704 four-colored diamond
Related compounds
Other anions Potassium dichromate
Potassium molybdate
Potassium tungstate
Other cations Sodium 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