How Sodium Iodide Is Used in Medicine, Industry & Experiments
Sodium iodide is a salt that is formed by the ionic reaction of sodium metal and iodine. The sodium iodide formula is NaI. Under standard conditions, it is a white, soluble solid which includes a 1:1 blend of sodium cations (Na+) and iodide anions (I−) in a lattice grid. Its main uses are in the field of medicine as a nutritional supplement and as additives. It is created when the salt is produced when acidic iodides respond with sodium hydroxide. It is a chaotropic salt. Sodium iodide is a metal iodide salt with a Na(+) counterion. It is an inorganic sodium salt and an iodide salt.
Sodium iodide has many interesting chemical and physical properties. It is created by the combination of an acid and a base yielding no by‐products.
The physical properties of sodium iodide are mentioned below.
The melting point of sodium iodide is 661 degrees C.
The boiling point of sodium iodide is 1304 degrees Celsius.
It is a strong deliquescent, which absorbs moisture and transforms into a solution.
It is a white and odourless crystal or powder
Properties of Sodium Lodide
Chemical Properties Of Sodium Iodide
Sodium iodide is extremely soluble in water and has an ionic crystal lattice structure.
Sodium iodide structure is given below:-
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Sodium iodide is not only dissolvable in water but also some other natural solvents. It is affected by air, moisture, and light, and strong NaI solid turns brownish colored on introduction to air or light, because of the development of iodine gas. It additionally responds explosively with various oxidants, solid acids, and bromine trihalides, creating iodine.
Iodides (counting sodium iodide) are oxidized by oxygen strongly (O2) to iodine gas(I2).
The resultant I2 and I-complex which is formed as a byproduct end up shaping the triiodide complex, which is rather yellow in color, in contrast to the white shade of sodium iodide.
Water quickens the oxidation procedure, and iodide can likewise create I2 gas by simple photooxidation. This is one of the biggest reasons sodium iodide ought to be put away under dim lights, low temperature, and low moisture conditions. It is better to maintain precautions and keep the solid away from external elements.
NaI + Cl2 -----> NaCl + I2
NaI + 4H2O ------> [Na(H2O)4]+ + I-
Hot sodium will likewise react along with halogen elements such as bromine or iodine gas fumes to create sodium bromide or sodium iodide. Every one of the usual reactions which result in the formation of sodium iodide gives out an orange fire and a white solid ionic lattice structure.
Iodide has a negative charge which implies it holds additional electrons which act as its valency. When it can obtain other iodine atoms it can lose the electrons to form stable I2 gas. The lost electrons will be picked up by another dependent atom or molecule which will be reduced into making iodide a good reducing agent.
Uses of Sodium Lodide
Sodium iodide is regularly utilized as a dietary iodine supplement and used to prepare pure NaCl as for table salt (NaCl). It is used to treat and prevent iodine deficiency. This disease can adversely affect the endocrine system. But NaI can help alleviate the symptoms by providing a source of iodine.
Another regular usage of (Sodium iodide formula) NaI is in atomic medication, as radioactive sodium iodide, (for example, NaI125 and NaI131) . Its similar subordinates are significant radiopharmaceuticals that are utilized for stopping and preventing thyroid malignant growth and hyperthyroidism, and furthermore as imaging tracers.
Sodium iodide is additionally utilized as a reagent in chemical combinations to get the resultant different alkyl iodides for other uses.
This halide salt is utilized in medication as a tracer and detector for such medical gadgets as computer‐assisted tomography outputs and PET scans.
FAQs on Sodium Iodide: Essential Guide for Chemistry Students
1. What is Sodium Iodide and what is its chemical formula?
Sodium Iodide is an inorganic compound and an ionic salt formed from the chemical reaction between sodium metal and iodine. It is a white, crystalline solid. The chemical formula for Sodium Iodide is NaI, which represents one atom of sodium (Na) ionically bonded to one atom of iodine (I).
2. What are the main physical and chemical properties of Sodium Iodide?
Sodium Iodide exhibits several distinct properties. As per the CBSE syllabus, key properties include:
- Appearance: It is a white, crystalline, and odourless solid.
- Solubility: It is highly soluble in water and also soluble in alcohols like ethanol and methanol.
- Melting and Boiling Points: It has a high melting point of 661 °C and a boiling point of 1304 °C, characteristic of ionic compounds.
- Hygroscopic Nature: Anhydrous NaI is hygroscopic, meaning it readily absorbs moisture from the air.
- Reactivity: It acts as a source of iodide ions and is used in various chemical reactions, such as the Finkelstein reaction in organic chemistry.
3. What are some important real-world applications and uses of Sodium Iodide?
Sodium Iodide has several significant applications in different fields. Its primary uses include:
- Nutritional Supplement: It is used to iodize table salt (iodised salt) to prevent iodine deficiency disorders like goitre.
- Medical Field: In medicine, radioactive iodine in the form of sodium iodide (I-131) is used in radiotherapy for treating thyroid cancer and in medical imaging.
- Organic Chemistry: It is a key reagent in the Finkelstein reaction, which is used to convert alkyl chlorides or bromides into alkyl iodides.
- Scintillation Detectors: Thallium-doped Sodium Iodide crystals, NaI(Tl), are used as scintillation detectors for detecting gamma rays in fields like nuclear physics and medical diagnostics.
4. How can a student chemically distinguish between Sodium Iodide (NaI) and Sodium Chloride (NaCl) in a lab?
To distinguish between Sodium Iodide and Sodium Chloride, the silver nitrate (AgNO₃) test is used. First, aqueous solutions of both salts are prepared. When a few drops of silver nitrate solution are added:
- In the Sodium Chloride (NaCl) solution, a curdy white precipitate of Silver Chloride (AgCl) is formed. This precipitate is soluble in ammonium hydroxide solution.
Reaction: NaCl(aq) + AgNO₃(aq) → AgCl(s) + NaNO₃(aq) - In the Sodium Iodide (NaI) solution, a pale yellow precipitate of Silver Iodide (AgI) is formed. This precipitate is insoluble in ammonium hydroxide solution.
Reaction: NaI(aq) + AgNO₃(aq) → AgI(s) + NaNO₃(aq)
The distinct colour and solubility of the precipitates allow for clear identification.
5. Why does Sodium Iodide react with concentrated sulphuric acid to produce iodine, while Sodium Chloride does not?
The difference in reactivity is due to the varying reducing power of the halide ions. The iodide ion (I⁻) is a significantly stronger reducing agent than the chloride ion (Cl⁻). When NaI reacts with concentrated sulphuric acid (H₂SO₄), the iodide ion is strong enough to reduce the sulphuric acid, getting oxidized itself to form purple iodine (I₂) vapour. In contrast, the chloride ion (Cl⁻) is a weak reducing agent and is not powerful enough to reduce concentrated H₂SO₄. Therefore, the reaction between NaCl and concentrated H₂SO₄ is a simple acid-base displacement reaction that produces hydrogen chloride gas (HCl), not chlorine gas.
6. Is Sodium Iodide an ionic or a covalent compound? Explain the nature of its bonding.
Sodium Iodide (NaI) is an ionic compound. The bonding occurs due to the large difference in electronegativity between the sodium (Na) atom and the iodine (I) atom. Sodium, being a Group 1 metal, readily loses one electron to form a positively charged cation (Na⁺). Iodine, a halogen, readily accepts one electron to form a negatively charged anion (I⁻). The strong electrostatic force of attraction between these oppositely charged ions (Na⁺ and I⁻) forms the ionic bond, resulting in a stable crystal lattice structure.
7. What happens to Sodium Iodide when it is exposed to air for a long time?
When Sodium Iodide is exposed to air and moisture for an extended period, it undergoes a slow oxidation process. The iodide ions (I⁻) are oxidized by atmospheric oxygen to form elemental iodine (I₂). This is why old samples of Sodium Iodide often appear yellowish or brownish in colour, which is the characteristic colour of iodine. This reaction is a key reason why NaI should be stored in a well-sealed, airtight container away from light and moisture to maintain its purity.
