Nomenclature
CAS number: 7784-25-0
Sulfuric acid aluminum ammonium salt (2:1:1); ammonium aluminum sulfate; burnt ammonium alum; exsiccated ammonium alum.
AlH
4NO
8S
2; mol wt 237.15.
Al 11.38%, H 1.70%, N 5.91%, O 53.97%, S 27.04%.
AlNH
4(SO
4)
2.
Description and references
Prepn: Gmelins, Aluminum (8th ed) 35B, pp 508-515 (1934). Dodecahydrate crystal
structure: Larson, Cromer, Acta Crystallogr. 22, 793 (1967); enthalpy of soln and crystn: J. Fisher et al., J. Solution Chem. 24, 659 (1995); properties of mixed aqueous solns: J.
W. Mullin, M. Sipek, J. Chem. Eng. Data 27, 181 (1982); V. Hostomska, J. Hostomsky, ibid. 51, 243 (2006).
Properties
About 97-98% pure, the balance is chiefly excess
Al2O3. White powder. One gram dissolves in
about 20 ml cold, 1.5 ml boiling water, usually incompletely. Practically
insol in alcohol. Keep well closed.Derivative
Dodecahydrate.
Nomenclature
CAS number: 7784-26-1
Ammonium alum.
AlH
4NO
8S
2.12H
2O; mol wt 453.33.
Al 5.95%, H 6.23%, N 3.09%, O 70.59%, S 14.15%.
Properties
Colorless crystals, white granules or powder;
styptic taste. d 1.65. mp 94.5°. At
about 250° becomes anhydr; decomposes above 280°. One gram dissolves
in 7 ml water, 0.5 ml boiling water. Freely sol in glycerol. Practically
insol in alcohol. The aq soln is acid to litmus; pH of 0.05 molar
soln 4.6.Use
Purifying drinking water; in baking powders; dyeing
and printing fabrics; manuf pigments, lakes, artificial gems, paper,
vegetable glue, marble and porcelain cements; fireproofing; tanning;
electrolytic copperplating; in prepn of high-purity aluminum compounds;
buffer in analytical chemistry.
See also Aluminum Potassium Sulfate.
Therapeutic Category
Astringent; hemostatic.
Therapeutic Category (Veterinary)
Astringent; hemostatic.
Keywords
Ammonium Alum: Astringent; Hemostatic