Nomenclature
CAS number: 10043-67-1
Sulfuric acid aluminum potassium salt (2:1:1).
AlKO
8S
2; mol wt 258.21.
Al 10.45%, K 15.14%, O 49.57%, S 24.84%.
KAl(SO
4)
2.
Description and references
Prepn: Gmelins, Aluminum (8th ed.) 35B, 453-477 (1934). Crystal structure: Manoli et al., Bull. Soc. Chim. Fr. 1970, 98; of dodecahydrate: Larson, Cromer, Acta Crystallogr. 22, 793 (1967).
Derivative
Anhydrous.
Nomenclature
Burnt alum; exsiccated alum. Properties
Usually about 97-98% pure. White powder; styptic
taste; attracts moisture from the air. One gram dissolves in about
20 ml cold or 1 ml boiling water, usually incompletely; practically
insol in alcohol. Keep well closed.Derivative
Dodecahydrate.
Nomenclature
7784-24-9; Alum; potassium alum; kalinite. AlKO
8S
2.12H
2O; mol wt 474.39.
Al 5.69%, K 8.24%, O 67.45%, S 13.52%, H 5.10%.
Properties
The technical product is also known as alum flour, alum meal, cube alum. It is about 99.5% pure. Colorless, odorless, hard, large,
transparent crystals or cryst fragments or white, cryst powder; sweetish,
astringent taste. Stable at ordinary temp; when kept for a long time
at 60-65° (or over H2SO4) loses 9 H2O which is reabsorbed on exposure to air. Becomes anhydr at about
200°; at higher temp loses SO3 and becomes basic and incompletely
sol in water. d 1.725. mp 92.5°. One
gram dissolves in 7.2 ml water, in 0.3 ml boiling water; freely sol
in glycerol. Insol in alcohol. The aq soln is acid; pH of 0.2 molar
aq soln 3.3.Use
In dyeing, printing fabrics; manuf dyes, lakes,
paper, vegetable glue, marble cement, porcelain cement, explosives;
in tanning, hardening gelatin, baking powders, purifying water, clarifying
sugar, hardening plaster casts; electrolytic copperplating; as catalyst
in synthesis of ammonia; in buffers; as flocculating reagent; as mordant
in staining with carmine, eosine, hematoxylin; clarifier (as alumina
cream); identifying coloring matters; hardening agent in microscopy.
Therapeutic Category
Astringent.
Therapeutic Category (Veterinary)
Astringent.
Keywords
Astringent