Potash Alum

Potassium Alum USP Grade Specifications

AlK(SO4)2-12H2O -- 474.39Sulfuric acid, aluminum potassium salt (2:1:1), dodecahydrate.Aluminum potassium sulfate (1:1:2) dodecahydrate [CAS 7784-24-9].Anhydrous 258.21 [CAS 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, crystalipitate 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.