Alum chrome extra pure

Alum chrome extra pure, commonly known as Chrome Alum or Chromium(III) Potassium Sulfate, is represented chemically as

KCr(SO

4

)

2

⋅

12

H

2

O

KCr(SO

4

)

2

⋅12H

2

O.​

Chemical Description

Chemical Formula:

KCr(SO

4

)

2

⋅

12

H

2

O

KCr(SO

4

)

2

⋅12H

2

O​

Molar Mass: 499.4 g/mol (dodecahydrate)​

Appearance: Dark purple to nearly black crystalline powder​

Density: 1.826 g/cm³ (dodecahydrate)​

Melting Point: 75–90°C (decomposes with loss of water)​

Solubility: Highly soluble in water; insoluble in alcohol​

Properties and Uses

Leather Tanning: Primary use is in the leather tanning industry to stabilize collagen fibers​

Dyeing and Mordant: Acts as a mordant in fabric dyeing due to its ability to fix dyes​

Historical Photography: Used as a hardening agent for gelatin emulsions in photographic processing​

Laboratory Reagent: Used for analytical and research purposes, especially in the preparation of chrome salts and other chromium compounds​

Physical Properties: Solutions are dark violet, turning green upon heating above 50°C due to the formation of different chromium(III) complexes​

Safety

Non-flammable: Chrome alum is not flammable​

Handling: Avoid inhalation or ingestion, and use protective equipment when handling the pure material, especially in laboratory or industrial settings​

“Extra pure” chrome alum refers to a highly purified form, suitable for sensitive analytical and laboratory uses where contaminant levels must be extremely low.

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