Sodium iodide
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| Sodium iodide | |
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| Identifiers | |
| CAS number | [7681-82-5] |
| RTECS number | WB6475000 |
| Properties | |
| Molecular formula | NaI |
| Molar mass | 149.89 g/mol |
| Appearance | White solid. |
| Density | 3.67 g/cm³, solid |
| Melting point |
660°C |
| Boiling point |
1304°C |
| Solubility in water | 184 g/100 ml (25°C) |
| Structure | |
| Coordination geometry |
Octahedral |
| Hazards | |
| EU classification | Irritant (Xi). |
| NFPA 704 |
 0
2
1
|
| R-phrases | R36, R38, R42, R43, R61 |
| S-phrases | S26, S36, S37, S39 |
| Flash point | Non-flammable. |
| Related compounds | |
| Other anions | Sodium fluoride Sodium chloride Sodium bromide |
| Other cations | Lithium iodide Potassium iodide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Sodium iodide is a white, crystalline salt with chemical formula NaI used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.
| H2O | 184 |
| Liquid ammonia | 162 |
| Liquid sulfur dioxide | 15 |
| Methanol | 62.5 - 83.0 |
| Formic acid | 61.8 |
| Acetonitrile | 24.9 |
| Acetone | 28.0 |
| Formamide | 57 - 85 |
| Acetamide | 32.3 |
| Dimethylformamide | 3.7 - 6.4 |
| [1] | |
Contents |
[edit] Uses
Sodium iodide is commonly used to treat and prevent iodine deficiency.
Sodium iodide is used in polymerase chain reactions, and also (as an acetone solution) in the Finkelstein reaction, for conversion of an alkyl chloride into an alkyl iodide. This relies on the insolubility of sodium chloride in acetone to drive the reaction.
Sodium iodide crystals doped with thallium, NaI(Tl), when subjected to ionising radiation, emit photons (scintillate) and are used in scintillation detectors, traditionally in nuclear medicine, geophysics, nuclear physics, environmental measurements, etc. NaI(Tl) is the most widely used scintillation material and has the highest light output. The crystals are usually coupled with a photomultiplier tube, in a hermetically sealed assembly, as sodium iodide is hygroscopic. Fine tuning of some parameters (radiation hardness, afterglow, transparency) can be achieved by varying the conditions of the crystal growth. Crystals with 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.
[edit] Notes, references
- ^ Burgess, J. "Metal Ions in Solution" (Ellis Horwood, New York, 1978) ISBN 0-85312-027-7
