Potassium Chloride KCl Mol. Wt. 74.55 potassium chloride 〔7447-40-7〕 Content Potassium Chloride, when dried, contains not less than 99.0% of potassium chloride (KCl). Description Potassium Chloride occurs as colorless crystals or as a white powder. It is odorless and has a salty taste. Identification Potassium Chloride responds to all tests for Potassium Salt and for Chloride as described in the Qualitative Tests. Purity (1) Free acid and free alkali Weigh 5.0 g of Potassium Chloride, dissolve in 50 ml of freshly boiled and cooled water, and add 3 drops of phenolphthalein TS. The color of the solution does not change to pink. Add 0.30 ml of 0.02 mol/l sodium hydroxide. The color of the solution changes to pink. (2) Bromide Weigh 1.0 g of Potassium Chloride, and dissolve in water to make 100 ml. Measure 5 ml of this solution, add 3 drops of diluted hydrochloric acid (1 → 4) and 1 ml of chloroform, and add 3 drops of chloramine T TS while shaking. The color of the chloroform layer does not change to yellow to yellow-red. (3) Iodide Weigh 0.50 g of Potassium Chloride, dissolve in 10 ml of water, add 3 drops of ferric chloride solution (1 → 10) and 1 ml of chloroform, shake, allow to stand for 30 minutes, and shake again. The color of the chloroform layer does not change to red-purple to purple. (4) Heavy metals Not more than 10 µg/g as Pb (2.0 g, Method 1, Control solution Lead Standard Solution 2.0 ml). (5) Calcium or magnesium Weigh 0.20 g of Potassium Chloride, dissolve in 20 ml of water, add 2 ml of ammonia TS, 2 ml of ammonium oxalate solution (1 → 30), and 2 ml of disodium phosphate solution (1 → 8), and allow to stand for 5 minutes. The solution does not become turbid. (6) Sodium Weigh 0.20 g of Potassium Chloride, dissolve in 100 ml of water, and proceed as directed under the Flame Coloration Test. No yellow color persists. (7) Arsenic Not more than 4.0 µg/g as As2O3 (0.50 g, Method 1, Apparatus B). Loss on Drying Not more than 1.0% (105℃, 2 hours). Assay Weigh accurately about 0.25 g of Potassium Chloride, previously dried, transfer into a flask with a ground-glass stopper, dissolve in 50 ml of water, add 50 ml, exactly measured, of 0.1 mol/l silver nitrate while shaking. Then add 3 ml of nitric acid and 5 ml of nitrobenzene while shaking, and shake vigorously. Add 2 ml of ferric ammonium sulfate TS, and titrate the excess silver nitrate with 0.1 mol/l ammonium thiocyanate. 1 ml of 0.1 mol/l silver nitrate = 7.455 mg of KCl