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Potassium chromate

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Title: Potassium chromate  
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Subject: Chromium, Potassium, Tarapacaite, Chromate and dichromate, Potassium tetraperoxochromate(V)
Collection: Chromates, Oxidizing Agents, Potassium Compounds
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Potassium chromate

Potassium chromate
Names
IUPAC name
Potassium chromate
Other names
Chromic acid, (K2CrO4), dipotassium salt
Identifiers
 Y
ChEBI  N
ChemSpider  N
EC number 232-140-5
Jmol-3D images Image
PubChem
RTECS number GB2940000
Properties
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)
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
1.74
Structure
rhombic
Hazards
Safety data sheet Chemical Safety Data
Carc. Cat. 2
Muta. Cat. 2
Toxic (T)
Irritant (Xi)
Dangerous for the environment (N)
R-phrases R50/53
S-phrases S53, S45, S60, S61
NFPA 704
0
3
1
OX
Related compounds
Other anions
Potassium dichromate
Potassium molybdate
Potassium tungstate
Other cations
Sodium chromate
Calcium chromate
Barium chromate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 N  (: Y/N?)

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]

Contents

  • General information 1
    • Physical properties 1.1
  • Production 2
  • Reactions 3
  • Applications 4
  • Occurrence 5
  • Safety 6
  • References 7

General information

Physical properties

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

Production

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

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

Applications

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

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.

Safety

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

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