Chrome alum

• Alum
• Chromium potassium sulfate
• Potassium chromium ( III ) sulfate dodecahydrate

• 7788-99-0 ( dodecahydrate )
• 10141-00-1 (anhydrous)

Odorless, violet to black crystalline powder

Fixed

1.83 g · cm -3 ( 20 ° C)

89 ° C

Well in water ( 244 g · l-1 at 25 ° C)

Attention

> 3500 mg · kg -1 ( LD50, rat, oral)

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Chromium ( III) potassium sulfate dodecahydrate (also alum, chromium potassium sulfate or potassium chromium ( III ) sulfate dodecahydrate ) is a crystalline compound consisting of the elements chromium, potassium, sulfur and oxygen, the hydrogen hydrate additionally. The compound belongs to the group of alums.

The same crystal with a view of the triangular surfaces ...

And ... from above.

Production and representation

Chromium potassium sulfate is produced by the reaction of potassium dichromate and sulfuric acid. Ethanol as a reducing agent which is oxidized to acetaldehyde is used.

Use

Chromium ( III) potassium sulfate dodecahydrate is used for tanning leather.