Potassium Iodide: KI; mol. wt. 166.02. K 23.55%, I 76.45%.

Potassium iodide of commerce contains about 99.5% KI.

Colorless or white, cubical crystals, white granules, or powder. Slightly deliquescent in moist air; on long exposure to air becomes yellow due to liberation of iodine, and small quantities of iodate may be formed; light and moisture accelerate the decomposition. Aq. solns. also become yellow in time due to oxidation, but a small amount of alkali prevents it. d. 3.12. m. 773°; volatilizes at higher temp. One gram dissolves in 0.7 ml. water, 0.5 ml. boil. water, 22 ml. alcohol, 8 ml. boil. alcohol, 51 ml. absolute alcohol, 8 ml. methanol, 75 ml. acetone, 2 ml. glycerol, about 2.5 ml. glycol. Potassium iodide solns. readily dissolve elemental iodine. The aq. soln. is neutral or, usually, slightly alkaline. pH: 7-9.

Thirty g. KI with 21 ml. water gives 30 ml. of a saturated soln. at 25°C.

Incompat. Alkaloidal salts, chloral hydrate, tartaric and other acids, calomel, potassium chlorate, metallic salts.

Use: Manuf. photographic emulsions; in animal and poultry feeds to the extent of 10-30 parts per million; in table salt and in some drinking water; also in anal. chemistry.

Grades available: Reagent, U.S.P., technical.

Med. Use: See Iodine.

Caution: Iodism occurs in sensitive individuals.

Dose: 0.3 to 1.3 g.

Vet. Use: As for sodium iodide.

Potassium Iodide-Theocalcin. Usually marketed in tablets each containing 0.5 g. theocalcin and 0.1 g. potassium iodide.