Sodium iodide

Sodium iodide

Names
IUPAC name Sodium iodide
Other names Sodium monoiodide
Properties
Chemical formula	NaI
Molar mass	149.89 g/mol
Appearance	White solid
Odor	Odorless
Density	3.67 g/cm3
Melting point	661 °C (1,222 °F; 934 K)
Boiling point	1,304 °C (2,379 °F; 1,577 K)
Solubility in water	158.7 g/100 ml (0 °C) 184.2 g/100 ml (25 °C) 227.8 g/100 ml (50 °C) 294 g/100 ml (70 °C) 302 g/100 ml (100 °C)
Solubility	Reacts with sulfuric acid Soluble in acetone, acetonitrile, ethanol, formamide, formic acid, isopropanol, methanol Slightly soluble in dimethylformamide, liq. sulfur dioxide Insoluble in halocarbons, hydrocarbons
Solubility in acetamide	32.3 g/100 g (41.5 °C)
Solubility in acetone	50.4425 g/100 g (25 °C)
Solubility in acetonitrile	24.9 g/100 g (25 °C)
Solubility in ammonia	162 g/100 g (25 °C)
Solubility in dichloromethane	0.009 g/100 g (25 °C)
Vapor pressure	~0 mmHg
Thermochemistry
Std molar entropy (So298)	91 J·mol−1·K−1
Std enthalpy of formation (ΔfHo298)	−288 kJ·mol−1
Hazards
Safety data sheet	Sigma-Aldrich
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (Median dose)	4.340 mg/kg (rat, oral)
Related compounds
Related compounds	Potassium iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Sodium iodide (NaI) is a chemical compound, a salt formed from sodium and iodine.

Properties

Chemical

Addition of a strong acid, like sulfuric acid will form hydroiodic acid, which decomposes to liberate elemental iodine.

2 NaI + H₂SO₄ → Na₂SO₄ + 2 HI

2 HI → H₂ + I₂

Physical

Sodium iodide is a colorless odorless solid, soluble in water.

Availability

Sodium iodide is sold by chemical suppliers.

Preparation

Can be made by neutralizing hydroiodic acid with sodium hydroxide/carbonate/bicarbonate:

NaOH + HI → NaI + H₂O

Na₂CO₃ + 2 HI → 2 NaI + H₂O + CO₂

NaHCO₃ + HI → NaI + H₂O + CO₂

Another route is addition of iodine to sodium thiosulfate.

2 Na₂S₂O₃ + I₂ → 2 NaI + Na₂S₄O₆

Projects

• Make hydrogen iodide and hydroiodic acid
• Make elemental iodine
• Finkelstein reaction

Handling

Safety

Sodium iodide has low toxicity.

Storage

Sodium iodide should be kept in closed bottles, plastic or glass.

Disposal

Can be recycled or dumped in trash.

References

Relevant Sciencemadness threads

• Making sodium iodide from iodine