Sodium iodide

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Sodium iodide
Sodium iodideSodium iodide
Identifiers
CAS number7681-82-5 YesY
13517-06-1 (dihydrate)
PubChem5238
ChemSpider5048 YesY
UNIIF5WR8N145C YesY
ChEBICHEBI:33167 YesY
ChEMBLCHEMBL1644695 N
RTECS numberWB6475000
Jmol-3D imagesImage 1
Properties
Molecular formulaNaI
Molar mass149.89 g/mol
Appearancewhite solid
deliquescent
Odorodorless
Density3.67 g/cm3
Melting point661 °C (1,222 °F; 934 K)
Boiling point1,304 °C (2,379 °F; 1,577 K)
Solubility in water178.8 g/100 mL (20 °C)
184 g/100 mL (25 °C)
294 g/100 mL (70 °C)
302 g/100 mL (100 °C)
Solubilitysoluble in ethanol and acetone (39.9 g/100 mL)
Acidity (pKa)8-9.5
Refractive index (nD)1.7745
Structure
Coordination
geometry
Octahedral
Thermochemistry
Std molar
entropy
So298
91 J·mol−1·K−1[1]
Std enthalpy of
formation
ΔfHo298
−288 kJ·mol−1[1]
Hazards
MSDS[1]
EU IndexNot listed
Main hazardsIrritant, can harm the unborn child
Flash pointNon-flammable
Related compounds
Other anionsSodium fluoride
Sodium chloride
Sodium bromide
Other cationsLithium iodide
Potassium iodide
Rubidium iodide
Caesium iodide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references
 
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Sodium iodide
Sodium iodideSodium iodide
Identifiers
CAS number7681-82-5 YesY
13517-06-1 (dihydrate)
PubChem5238
ChemSpider5048 YesY
UNIIF5WR8N145C YesY
ChEBICHEBI:33167 YesY
ChEMBLCHEMBL1644695 N
RTECS numberWB6475000
Jmol-3D imagesImage 1
Properties
Molecular formulaNaI
Molar mass149.89 g/mol
Appearancewhite solid
deliquescent
Odorodorless
Density3.67 g/cm3
Melting point661 °C (1,222 °F; 934 K)
Boiling point1,304 °C (2,379 °F; 1,577 K)
Solubility in water178.8 g/100 mL (20 °C)
184 g/100 mL (25 °C)
294 g/100 mL (70 °C)
302 g/100 mL (100 °C)
Solubilitysoluble in ethanol and acetone (39.9 g/100 mL)
Acidity (pKa)8-9.5
Refractive index (nD)1.7745
Structure
Coordination
geometry
Octahedral
Thermochemistry
Std molar
entropy
So298
91 J·mol−1·K−1[1]
Std enthalpy of
formation
ΔfHo298
−288 kJ·mol−1[1]
Hazards
MSDS[1]
EU IndexNot listed
Main hazardsIrritant, can harm the unborn child
Flash pointNon-flammable
Related compounds
Other anionsSodium fluoride
Sodium chloride
Sodium bromide
Other cationsLithium iodide
Potassium iodide
Rubidium iodide
Caesium iodide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Sodium iodide is a white, crystalline salt with the chemical formula NaI, and is used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.

Production[edit]

Sodium iodide is manufactured from the reaction between iodine and sodium hydroxide.

Uses[edit]

Food supplement[edit]

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.[2]

Organic synthesis[edit]

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

R-Cl + NaI → R-I + NaCl

Radiation physics and medicine[edit]

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.

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[3] or as radiolabeling tracers in imaging (see Isotopes of iodine > Radioiodines I-123, I-124, I-125, and I-131 in medicine and biology).

Solubility data[edit]

Solubility of NaI in various solvents
(g NaI / 100g of solvent at 25°C)
H2O184
Liquid ammonia162
Liquid sulfur dioxide15
Methanol62.5 - 83.0
Formic acid61.8
Acetonitrile24.9
Acetone28.0
Formamide57 - 85
Acetamide32.3
Dimethylformamide3.7 - 6.4
[4]
Dichloromethane0.009 [5]

See also[edit]

References[edit]

  1. ^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X. 
  2. ^ Lyday, Phyllis A. "Iodine and Iodine Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim, ISBN 978-3-527-30673-2 doi:10.1002/14356007.a14_381 Vol. A14 pp. 382–390.
  3. ^ The Free Dictionary: sodium iodide 131I
  4. ^ Burgess, J. "Metal Ions in Solution" (Ellis Horwood, New York, 1978) ISBN 0-85312-027-7
  5. ^ Danil de Namor, A.F.; J. Chem. Soc., Faraday Trans. 1, 1989,85, 2705-2712 DOI: 10.1039/F19898502705

External links[edit]