Potash Alum

Potassium Alum USP

AlK(SO4)2·12H2O 474.39
Sulfuric acid, aluminum potassium salt (2:1:1), dodecahydrate.
Aluminum potassium sulfate (1:1:2) dodecahydrate [7784-24-9].
Anhydrous 258.21 [10043-67-1].
Potassium Alum contains not less than 99.0 percent and not more than 100.5 percent of AlK(SO4)2, calculated on the dried basis.

Packaging and storage— Preserve in tight containers, and store at room temperature.
Identification—
A: Add 1 N sodium hydroxide drop wise to a solution of it (1 in 20): a precipitate is formed that dissolves in an excess of the reagent. Ammonia is not evolved (distinction from Ammonium Alum).
B: Hold it in a non-luminous flame: a violet color is imparted to the flame.
C: Add 10 mL of sodium bitartrate TS to 5 mL of a saturated solution of it: a white, crystalline precipitate is formed within 30 minutes.
D: A solution (1 in 20) responds to the tests for Aluminum and for Sulfate.
Loss on drying— Transfer 2.0 g, in a tarred porcelain crucible, to a muffle furnace at 200. Increase the temperature to 400 , and dry at 400 to constant weight. Cool in a desiccator, and weigh: it loses between 43.0% and 46.0% of its weight.
Heavy metals—the limit is 0.002%.
Iron— Add 5 drops of potassium ferrocyanide TS to 20 mL of a solution (1 in 150): no blue color is produced immediately.

Aluminum Potassium Sulfate; Potassium Alum FCC Food Grade, Potash Alum

AlK(SO4)2·12H2O Formula wt 474.38
INS: 522 CAS: [7784-24-9]

DESCRIPTION
Aluminum Potassium Sulfate occurs as large, transparent crystals or crystalline fragments, or as a white crystalline powder. One gram dissolves in 7.5 mL of water at 25° and in about 0.3 mL of boiling water. Its solutions are acid to litmus. It is insoluble in alcohol, but is freely soluble in glycerin.
Function: Buffer; neutralizing agent; firming agent.

REQUIREMENTS
Identification: A 1:20 aqueous solution gives positive tests for Aluminum, for Potassium, and for Sulfate.
Assay: Not less than 99.5% and not more than 100.5% of AlK(SO4)2·12H2O.
Ammonium Salts: Passes test.
Fluoride: Not more than 0.003%.
Lead: Not more than 3 mg/kg.
Selenium: Not more than 0.003%.

Alum BP, Potash Alum

Aluminium Potassium Sulphate
AlK(SO4)2,12H2O__474.4__7784-24-9

DEFINITION
Content
99.0 per cent to 100.5 per cent of AlK(SO4)2,12H2O.

CHARACTERS
Appearance
Granular powder or colourless, transparent, crystalline masses.
Solubility
Freely soluble in water, very soluble in boiling water, soluble in glycerol, practically insoluble in ethanol (96 per cent).

IDENTIFICATION
A. Solution S (see Tests) gives the reactions of sulphates.
B. Solution S gives the reaction of aluminium.
C. Shake 10 ml of solution S with 0.5 g of sodium bicarbonate R and filter. The filtrate gives reaction (a) of potassium.

TESTS
Solution S
Dissolve 2.5 g in water R and dilute to 50 ml with the same solvent.
Appearance of solution
Solution S is clear and colourless.
pH: 3.0 to 3.5.
Ammonium: Maximum 0.2 per cent.
Iron: Maximum 100 ppm.
Heavy metals: Maximum 20 ppm.

Aluminum Potassium Sulfate Dodecahydrate ACS Analytical Reagent

AlK(SO₄)₂ ^. 12H₂O

Formula Wt 474.39
CAS Number 7784-24-9

REQUIREMENTS
Assay   98.0-102.0% AlK(SO₄)₂ ^. 12H₂O

MAXIMUM ALLOWABLE
Insoluble matter ……… 0.005%
Chloride (Cl) …………. 5 ppm
Ammonium (NH₄) ….. 0.005%
Heavy metals (as Pb) . 0.001%
Iron (Fe) ………………. 0.001%
Sodium (Na) …………. 0.02%