Sodium iodide

Sodium iodide

Identifiers
CAS Number	7681-82-5 Y 13517-06-1 (dihydrate) N
ChEBI	CHEBI:33167 Y
ChEMBL	ChEMBL1644695 N
ChemSpider	5048 Y
Jmol 3D model	Interactive image
PubChem	5238
RTECS number	WB6475000
UNII	F5WR8N145C Y
InChI InChI=1S/HI.Na/h1H;/q;+1/p-1 Y Key: FVAUCKIRQBBSSJ-UHFFFAOYSA-M Y InChI=1/HI.Na/h1H;/q;+1/p-1 Key: FVAUCKIRQBBSSJ-REWHXWOFAL
SMILES [Na+].[I-]
Properties
Chemical formula	NaI
Molar mass	149.89 g/mol
Appearance	white solid deliquescent
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)
Acidity (pKa)	8–9.5
Refractive index (nD)	1.7745
Structure
Crystal structure	Halite
Coordination geometry	Octahedral
Thermochemistry
Std molar entropy (So298)	91 J·mol−1·K−1
Std enthalpy of formation (ΔfHo298)	−288 kJ·mol−1
Vapor pressure	{{{value}}}
Related compounds
Other anions	Sodium fluoride Sodium chloride Sodium bromide
Other cations	Lithium iodide Potassium iodide Rubidium iodide Caesium iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Sodium iodide (chemical formula NaI) is the salt of sodium and iodide. It is a white, crystalline solid that is used mainly as a nutritional supplement and in organic chemistry. It is produced industrially by acidic iodides and sodium hydroxide.

Uses

Food supplement

Sodium iodide, as well as potassium iodide, is commonly used to treat and prevent iodine deficiency. Iodized table salt contains one part sodium or potassium iodide to 100,000 parts of sodium chloride.

Organic synthesis

Monatomic NaI chains grown inside double-wall carbon nanotubes.

Sodium iodide is used for conversion of an alkyl chlorides into an alkyl iodides. This method, the Finkelstein reaction, relies on the insolubility of sodium chloride in acetone to drive the reaction:

R-Cl + NaI → R-I + NaCl

Nuclear medicine

Some radioactive iodide salts of sodium, including [¹²⁵I]NaI and [¹³¹I]NaI, have radiopharmaceutical uses, such as in the treatment of thyroid cancer and hyperthyroidism or as radiolabeling tracers in imaging (see Isotopes of iodine > Radioiodines I-123, I-124, I-125, and I-131 in medicine and biology).

Thallium-doped NaI(Tl) scintillators

Sodium iodide activated with thallium, NaI(Tl), when subjected to ionizing radiation, emits photons (i.e., scintillate) and is used in scintillation detectors, traditionally in nuclear medicine, geophysics, nuclear physics, and environmental measurements. NaI(Tl) is the most widely used scintillation material. The crystals are usually coupled with a photomultiplier tube, in a hermetically sealed assembly, as sodium iodide is hygroscopic. Fine-tuning of some parameters (i.e., radiation hardness, afterglow, transparency) can be achieved by varying the conditions of the crystal growth. Crystals with a higher level of doping are used in X-ray detectors with high spectrometric quality. Sodium iodide can be used both as single crystals and as polycrystals for this purpose. The wavelength of maximum emission is 415 nm.

Solubility data

Sodium iodide exhibits high solubility in some organic solvents, unlike sodium chloride or even bromide. Its solubility of NaI in various solvents (g NaI/100 g of solvent at 25 °C)

H2O	184.2
Liquid ammonia	162
Liquid sulfur dioxide	15
Methanol	62.5–83.0
Formic acid	61.8
Acetonitrile	24.9
Acetone	50.4425
Formamide	57–85
Acetamide	32.3 (41.5 °C)
Dimethylformamide	3.7–6.4
Dichloromethane	0.009

See also

• Gamma spectroscopy
• Scintillation counter
• Teratology

External links

• International Chemical Safety Card 1009 – Sodium Iodide (Anhydrous)
• Material Safety Data Sheet (MSDS) – Safety data for sodium iodide
• Sodium iodide as medication — Consumer Information