Overview

Potassium iodide (poe-TAS-ee-yum EYE-oh-dide) is a white crystalline, granular, or powdered solid with a strong, bitter, salty taste. It is used as a feed additive, a dietary supplement, in photographic films, and in chemical research.

Key Facts

Formula:

KI

Elements:

Potassium, iodine

Compound Type:

Binary salt (inorganic)

State:

Solid

Molecular Weight:

166.00 g/mol

Melting Point:

681°C (1260°F)

Boiling Point:

1323°C (2413°F)

Solubility:

Soluble in water, ethyl alcohol, acetone, and glycerol

How It Is Made

A number of methods are available for the preparation of potassium iodide. In one procedure, elemental iodine (I₂) is added to a solution of potassium hydroxide (KOH): I₂ + 6KOH → 5KI + KIO₃ + 3H₂O. The potassium iodide formed is separated from the potassium iodate (KIO₃) by fractional crystallization. That is, the solution is warmed and then cooled. As the temperature falls, the two compounds, potassium iodide and potassium iodate, crystalize out at...