Sodium Iodide - NaI

What is Sodium Iodide?

Sodium iodide is an ionic compound produced by the addition of sodium hydroxide or sodium carbonate to hydriodic acid. The chemical formula for sodium iodide is NaI. It is a colourless cubic crystals that are soluble in polar solvents. It is one of the oldest members of the optical engineering family and is considered by many scientists as a standard optical device in the field of detection technology.

Other names – Sodium monoiodide


Sodium Iodide


3.67 g/cm³

Molecular Weight/ Molar Mass

149.89 g/mol

Charge of Na


Boiling Point

1,304 °C

Melting Point

661 °C

Chemical Formula


Sodium Iodide Structure – NaI

Sodium Iodide

Physical Properties of Sodium Iodide – NaI




White solid, deliquescent

Covalently-Bonded Unit


Heat capacity





Soluble in water, acetone and ethanol.

Chemical Properties of Sodium Iodide – NaI

  • Sodium iodide reacts with sulphuric acid results in the formation of hydrogen iodide and sodium bisulfite. The chemical equation is given below.
  • NaI + H2SO4 → HI + NaHSO4

  • Sodium iodide reacts with chlorine, where chlorine replaces iodine forming sodium chloride and iodine.The chemical equation is given below.
  • Cl2 + 2NaI → 2 NaCl + I2

Uses of Sodium Iodide – NaI

  • Sodium iodide is used in medicine as a supplement for iodine to treat thyroid disorders.
  • Used in the treatment of actinobacillosis and actinomycosis in cattle.
  • A Small amount of Sodium iodide is added to the Sodium chloride to make “iodised salt’. This makes sure you get the iodide you need in your diet.

Practise This Question

The overall charge on the sodium chloride compound formed by the combination of an anion (Cl-) and a cation (Na+) is