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Sodium Iodide Formula – Structure, Properties, Uses, Sample Questions

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Being one of the two elements of our table salt is our biggest claim to fame.  Sodium combines with chlorine (Cl) to form sodium chloride (NaCl). Sodium is a reactive, soft metal with a low melting point and is commercially the most important of all alkali metals.   Sodium reacts with hydrogen at temperatures above 200 ºC to form sodium hydride. It also reacts with various metal halides to form sodium chloride and metals. With atomic number  11, it is represented by the symbol Na on the periodic table.

Iodide is a salt or ester of the mineral iodine. Iodine salts are weak reducing agents, many react with oxygen to form iodine. NCI Thesaurus (NCIt) Iodide is a halide anion and monoatomic iodine. It acts as a human metabolite.

What is Sodium Iodide?

Sodium iodide is an ionic compound formed by the chemical reaction of metal sodium and iodine. In standard conditions, it is a white and solid containing a 1:1 mixture (Na+) of a sodium cation (Na+) and a 1:1 mixture of iodide anion (I). 

It is mainly used in food additives and organic chemistry. The acid iodide is industrially manufactured as a  salt formed when reacting with sodium hydroxide. This is Chaotropic Salt.

Sodium Iodide Formula

Sodium iodide is an inorganic salt of the formula NaI. It is an important source of iodine. In industry, sodium iodide is produced by the reaction of hydroiodic acid or iodine with sodium hydroxide.

NaOH + HI → NaI + H2O

Structure of Sodium Iodide 

Sodium iodide has a chemical formula of NaI and a molar mass of 149.89 g/mol. It is a simple ionic compound composed of a sodium cation (Na+) and an iodide anion (I). Solid NaI has the same octahedral crystal geometry as sodium chloride (NaCl). Its chemical structure is:


Preparation of Sodium Iodide

Sodium iodide is produced commercially by the reaction of sodium hydroxide with iodine or hydroiodic acid. It can also be obtained by treating sodium carbonate with a solution of hydroiodic acid.

NaOH + HI → NaI + H2O

Physical Properties of Sodium Iodide

The Physical Properties of Sodium Iodide are,

  • The melting point of sodium iodide is 661 degrees Celsius.
  • Sodium iodide has a boiling point of 1304 degrees Celsius.
  • A highly deliquescent substance that absorbs moisture and turns into a solution.
  • White crystals or odorless powder.

Chemical Properties of Sodium Iodide

Sodium iodide is very dissolved in water to have an ion structure of a lattice of an ionic crystal grid. Iodide is not only rusted in water, but also in the other natural solvents, but it depends on air, moisture, and lung, and the strong northern solid is brown into the introduction of air. This creates iodine by responding to various oxidizers, solid acids, and bromine trifle explosions. 

The iodide is oxidized by oxygen (O2) to the long gas (I2). The generated I2 and I-complex form a yellow triiodide composite that is ultimately a yellowish color, in contrast to the white shade of iodine sodium. Water accelerates the oxidation process and iodide can also form I2 gas by simple photooxidation. This is one of the main reasons why sodium iodide should be stored in low light, low temperature, and low humidity conditions. It is recommended to take precautions and keep solids away from external elements.

NaI + Cl2  → NaCl + I2 

NaI + 4H2O → [Na(H2O)4]+ + I  

Hot sodium also reacts with halogen elements such as bromine or iodine vapor to form sodium bromide or sodium iodide. Each typical reaction leading to the formation of sodium iodide produces an orange flame and a white solid ion lattice. Iodide is negatively charged, meaning it contains an extra electron that acts as a valence. When another iodine atom can be gained, it can lose electrons to form the stable gas I2. The lost electrons are recovered by other dependent atoms or molecules, making iodine a good reducing agent.

Uses of Sodium Iodide

  • Sodium iodide is regularly used as a dietary iodine supplement and, like table salt (NaCl), is used to produce pure NaCl. This disease can negatively affect the endocrine system. However, NaI is a source of iodine and may help relieve symptoms.
  • Sodium Iodide is also used as a reagent in chemical combinations to produce various alkyl iodides for various purposes.
  • This halide salt is used medically as an indicator and detector in medical devices such as CT scans and PET scans.
  • Sodium Iodide is used in medicine as an iodine supplement for the treatment of thyroid disorders.
  • Used to treat actinomycosis and actinomycosis in cattle.

Sample Questions

Question 1: What is the chemical formula of salt?


To most people, salt refers to table salt, which is sodium chloride. Sodium chloride forms from the ionic bonding of sodium ions and chloride ions. There is one sodium cation (Na+) for every chloride anion (Cl–), so the chemical formula is NaCl.

Question 2: What is iodine made of?


Now the main sources of iodine are iodate minerals, natural brine deposits left by the evaporation of ancient seas, and brackish (briny) waters from oil and salt wells. Iodine is obtained commercially by releasing iodine from the iodate obtained from nitrate ores or extracting iodine vapor from the processed brine.

Question 3: Why is sodium iodide soluble in water?


NaI is an ionic compound that can dissolve in water due to the polar nature of water molecules. Iodine is made up of molecules of I2, which individually have no dipole moment (the I-I bond has no dipole as both iodine atoms have the same electronegativity).

Question 4: How does sodium iodide dissolve?


A compound dissolves in water whenever solvation energy (hydration energy in this case) is greater than lattice energy. Lattice energy is the energy required to break the lattice. Solvation energy is the energy released when a compound is solvated.

Question 5: Does pink Himalayan salt have iodine?


Himalayan salt has no added iodine, which may cause hypoactive thyroid in iodine-deficient individuals. There are no proven health benefits to using Himalayan salt, just like there is no benefit of using Himalayan salt lamps.

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Last Updated : 05 Dec, 2022
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