Sodium iodide (NaI) is a compound made up of sodium and iodine. It is commonly used in medicine as a source of iodine, which is essential for thyroid function.
| IUPAC Name | Sodium iodide |
| Molecular Formula | NaI |
| CAS Number | 7681-82-5 |
| Synonyms | Natrii iodidum, NaI, Halide salt of sodium, Sodium monoiodide, Sodium iodatum, Sodiumiodide, UNII-4L5IUN6BTH, EINECS 231-679-3, HSDB 595 |
| InChI | InChI=1S/Na.IH3/h;1H3/q+1;/p-1 |
Sodium Iodide Properties
Sodium Iodide Formula
The chemical formula of sodium iodide is NaI. It is a binary ionic compound consisting of Na+ and I- ions. The formula is important in determining the chemical properties and behavior of sodium iodide, such as its solubility and reactivity with other compounds.
Sodium Iodide Molar Mass
The molar mass of NaI is 149.89 g/mol. This value is obtained by adding the atomic masses of sodium and iodine in the compound. It is important to know the molar mass of a compound as it helps in determining the number of moles of the substance in a given sample.
Sodium Iodide Boiling Point
The boiling point of NaI is 1,304 degrees Celsius. This high boiling point is due to the strong ionic bond between Na and I atoms. NaI is a stable compound that can withstand high temperatures without decomposing.
Sodium Iodide Melting Point
The melting point of NaI is 661 degrees Celsius. It is a relatively low melting point for an ionic compound. The low melting point of NaI is due to the relatively weak ionic bond between the Na and I atoms.
Sodium Iodide Density g/ml
The density of NaI is 3.67 g/ml. The high density of NaI is due to the relatively large size of the iodine atom. The high density of NaI makes it useful as a shielding material in radiation therapy.
Sodium Iodide Molecular Weight
The molecular weight of NaI is 149.89 g/mol. This value is obtained by adding the atomic masses of Na and I in the compound. The molecular weight of NaI is important in determining the number of molecules in a given sample.
Sodium Iodide Structure
NaI has a crystal structure similar to that of sodium chloride. It consists of an array of positively charged Na+ ions and negatively charged I- ions, held together by strong ionic bonds. This structure results in a high melting and boiling point, as well as a high density.
| Appearance | White crystalline solid |
| Specific Gravity | 3.67 |
| Color | Colorless |
| Odor | Odorless |
| Molar Mass | 149.89 g/mol |
| Density | 3.67 g/cm³ |
| Melting Point | 661 °C |
| Boiling Point | 1,304 °C |
| Flash Point | Not applicable |
| Water Solubility | 184 g/L at 25 °C |
| Solubility | Soluble in ethanol, acetone, ammonia; insoluble in ether |
| Vapour Pressure | 1.33 Pa at 573 K |
| Vapour Density | Not applicable |
| pKa | 10.7 |
| pH | Neutral (7) |
Sodium Iodide Safety and Hazards
NaI is relatively safe to handle when used in its pure form. However, it can be dangerous if ingested or inhaled in large quantities. Ingestion can cause gastrointestinal irritation, while inhalation can cause respiratory irritation. NaI can also be a skin irritant and may cause burns upon contact with the skin. It is important to handle NaI with care, wearing appropriate protective equipment, such as gloves and goggles, and following proper safety protocols. NaI should be stored in a cool, dry place away from sources of heat and incompatible materials.
| Hazard Symbols | Xi (Irritant) |
| Safety Description | Avoid ingestion, inhalation, and skin contact. Wear protective equipment. |
| UN IDs | UN3077 |
| HS Code | 28276000 |
| Hazard Class | 9 – Miscellaneous hazardous materials |
| Packing Group | III |
| Toxicity | Low toxicity when used properly. Can cause irritation and burns upon contact with skin or eyes. Ingestion or inhalation of large amounts can cause respiratory and gastrointestinal irritation. |
Sodium Iodide Synthesis Methods
A variety of methods can synthesize NaI.
One common method involves the reaction of sodium hydroxide (NaOH) with hydroiodic acid (HI) to produce NaI and water. Another method involves the reaction of sodium carbonate (Na2CO3) with hydroiodic acid to produce NaI, carbon dioxide, and water.
Sodium metal reacts with iodine gas to produce NaI. This method involves combining sodium and iodine in a 1:1 molar ratio in an inert atmosphere, such as argon, to prevent oxidation of the sodium.
To synthesize NaI, one can react iodine with a solution of sodium sulfite and sodium hydroxide, resulting in a product that requires filtration and purification.
Another method to produce NaI is by reacting iodine with a solution of sodium thiosulfate and sodium hydroxide. The resulting product undergoes filtration, purification, and drying to yield pure NaI.
Sodium Iodide Uses
NaI is a versatile compound with a wide range of applications in various fields. Here are some common uses of NaI:
- Medical imaging: Used as a contrast agent in medical imaging, particularly in X-ray imaging and computed tomography (CT) scans.
- Nuclear medicine: Used in nuclear medicine as a radioactive tracer for diagnosing and treating thyroid conditions.
- Chemical synthesis: Used as a reagent in chemical synthesis, particularly in organic chemistry, for example, in the synthesis of certain pharmaceuticals.
- Radiation detection: Used as a scintillation detector in the detection of radiation, particularly in gamma spectrometry.
- Animal feed: Added to animal feed to prevent iodine deficiency in livestock and poultry.
- Photographic processing: In photographic processing, NaI forms silver iodide, which photographic film uses as a photosensitive material.
- Industrial applications: Also used in various industrial applications, such as in the production of dyes, pigments, and catalysts.
Questions:
Q: How many grams of NaI, must be used to produce 14.0 g of iodine, I2?
A: The molar mass of iodine is 254 g/mol and the molar mass of NaI is 149.9 g/mol. Therefore, to produce 14.0 g of iodine, 10.47 g of NaI must be used.
Q: Is sodium iodide soluble in water?
A: Yes, NaI is highly soluble in water, with a solubility of 184 g/L at 25°C.
Q: Is sodium iodide soluble?
A: NaI is soluble in a variety of solvents, including water, ethanol, and acetone.
Q: How many grams of NaI must be used to produce NaCl and 25.0 g of I2?
A: The balanced chemical equation for this reaction is 2 NaI + Cl2 → 2 NaCl + I2. Based on the stoichiometry of the equation, 73.47 g of sodium iodide (NaI) must be used to produce 25.0 g of iodine (I2) and an equivalent amount of sodium chloride (NaCl).