Question

What is the colour of potassium iodide?

Answer 1

Hint :Potassium iodide is an ionic compound made up of potassium ions and iodide ions. This compound crystallizes in the sodium chloride structure. It is produced industrially by treating the compound potassium hydroxide with iodine.

Complete Step By Step Answer:
The compound potassium iodide is a white crystalline salt having the chemical formula ${\text{KI}}$ . It is an oral antithyroid agent used in the prevention of radioactive iodine uptake. This compound absorbs water less readily than sodium iodide. Aged and impure samples of potassium iodide are yellow because of the slow oxidation of the salt to potassium carbonate and iodine. Potassium iodide is used with silver nitrate to prepare silver iodide which is an important chemical in film photography. It is also a component in disinfectants and hair treatment chemicals. This compound serves as a source of iodine in organic synthesis and also acts as a nucleophilic catalyst for the alkylation of alkyl chlorides and bromides. It is used to treat hyperthyroidism and to protect the thyroid gland when some types of radiopharmaceuticals are used. It is used as a nutritional supplement in the human diet and also in animal feeds. For humans, it is the most common additive used to iodise table salt.
Therefore, the colour of potassium iodide is white.

Note :
The oxidation of iodide causes slow loss of iodine content from iodized salts which are exposed to excess air. Potassium iodide slowly oxidizes to metal carbonate and elemental iodine on exposure to excess oxygen and carbon dioxide.