March 12, 2024 | UR Gate
Sodium Iodide (NaI): Definition, Preparation, and Uses
Sodium Iodide
Sodium iodide is a crystalline solid with the chemical formula NaI and a molecular weight of 149.89. It has a density of 3.67 grams/cm³ and a melting point of 651 degrees Celsius. When exposed to air, sodium iodide turns brown due to the liberation of iodine. This substance is highly soluble in water, soluble in ethanol, and acetic acid. It is known in two forms: anhydrous and hydrated, with the latter being dihydrated.
Preparation:
Sodium iodide can be prepared by the reaction of hydrogen iodide with sodium carbonate or sodium hydroxide:
HI + NaOH → NaI + H2O
Similar to potassium iodide, sodium iodide is known for its ability to dissolve iodine, forming a brown solution containing I3- ions.
Sodium iodide finds applications in photography, pharmaceuticals, and other industries.
Uses:
Sodium iodide, along with potassium iodide, is commonly used to treat and prevent iodine deficiency. Iodized table salt contains 10 parts per million of sodium iodide. Sodium iodide is also employed to convert alkyl chlorides into alkyl iodides. This reaction, known as the Finkelstein reaction, relies on the insolubility of sodium chloride in acetone to drive the reaction:
R−Cl + NaI → R−I + NaCl
Safety:
Sodium iodide has corrosive and irritating effects on the skin and mucous membranes.