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Potassium Iodide (KI) – Structure, Properties, and Uses

Sep 5, 2022

Respiration, digestion, photosynthesis, food preparation, burning fuels like coal and petroleum, washing clothes and home goods, and plenty of other activities are samples of how chemistry is employed in everyday life. We feature each of those tasks daily, and they all involve chemical processes. Mucus within the airways is loosened and variable using iodide. If you have persistent lung issues, this aids in clearing your cough so you can breathe more comfortably, like asthma, bronchitis, and emphysema. This drug is noted as an expectorant.

What is Potassium Iodide (KI)?

A metal-halide salt called iodide has an ionic connection between the potassium cation (K+) and the iodide anion (I). It is a colour range of white to colourless and appears as cubical crystals, powder, or white granules. It tastes salty and very bitter. Iodine and potash are mixed to form this chemical. It is on the World Health Organisation’s list of essential medicines because it is one amongst one of the most efficient and secure medications needed in a healthcare system. Since 1820, iodide has been used for medical purposes. It is included in the WHO’s list of essential medications. Both over-the-counter and generic versions of iodide are readily available. Salt can also be iodized using iodide.  A non-radioactive type of iodine called iodide (KI) may be used to prevent radioactive iodine (I131), one variety of stuff, from being absorbed by the thyroid. The chemical name for iodide is KI. It is used as a supplement for people whose diets include little iodine. It is taken orally.


Structure of iodide (KI Structure)

One potassium cation and one iodide anion, which are joined by an ionic connection, form an iodide molecule. The structure is illustrated as:



Properties of Potassium iodide

Physical Properties

  • IUPAC Name – potassium iodide
  • Molecular mass – 166.0028 g/mol
  • Chemical formula – KI
  • Density – 3.12 g/cm3
  • Boiling Point – 1,330 °C
  • Melting Point – 681 °C

Chemical Properties

By adding a chemical agent to iodide compounds, an I2 molecule is often created. The following is one in all the samples of such a response:

2KI + Cl2 → 2 KCl + I2


4KI + 2 CO2 + O2 → 2 K2CO3 + 2 I2

It is possible to use this substance as an iodide source in an exceeding sort of organic synthesis process. The creation of aryl iodides using the arena’s diazonium salts is one example of this.


Uses of Potassium Iodide

A) Uses in Medicine

  • Thyroid Defense

The following iodide dosage with iobenguane has been approved by the U.S. Food and Drug Administration (per 24 hours): babies under one-month-old: 16 mg; children between one and three years old: 32 mg; teenagers between three and eighteen years old: 65 mg; adults: 130 mg. Alternative dosing protocols are, however, advised by certain authorities. 

Although there is disagreement among authors regarding the length of thyroid blockade required, blocking is required for both the therapeutic and scintigraphic uses of iobenguane. Iobenguane sold commercially is labelled with iodine-123, and product labelling advises iodide administration one hour before radiopharmaceutical administration for all age groups. However, the European Association of Medical Specialists advises that iodide administration should start some days before radiopharmaceutical administration and continue until the day after the injection (for iobenguane labelled with either isotope). 


Iodine-131 diagnostic product labelling by the substantially longer half-life of this isotope and its greater risk to the thyroid, iobenguane advises iodide administration beginning daily before injection and continuing for five to 7 days after administration.

  • Nuclear Mishaps 

The recommended dietary allowance for iodine is 150 micrograms (0.15 mg) of iodine (as iodide) per day for an adult, which is approximately 700 times larger than the emergency 130-milligramme potassium iodide doses, which provide 100 milligrammes of iodide (the other 30 milligrammes are the potassium in the compound). A typical tablet contains 30 mg of excipients, such as binding agents, and 130 mg of potassium iodide, making it 160 mg in weight.


Potassium iodide cannot offer any protection against other radiation poisoning mechanisms or against dirty bombs that emit radionuclides other than those of iodine. Iodized salt doesn’t contain enough potassium iodide for this purpose. To equal the potassium iodide in one tablet, more than a kilogramme of salt (a potentially deadly dose) would be required.

B) Industrial uses

To create iodide (AgI), a vital component in film photography, KI is combined with caustic. Some cleaning agents and chemicals utilised in hair care products contain KI. In biomedical research, KI is additionally employed as a fluorescence quenching agent. This application uses the iodide ion’s collisional quenching of fluorescent molecules. Iodide functions as a fluorescence enhancer; however, adding KI in M-mM concentrations increases fluorescence intensity for a few fluorophores.


 Along with iodine, iodide could be a component of the electrolyte of dye-sensitised solar cells (DSSC).

C) Other Uses of iodide

  • Both in human diets and animal feeds, it is a nutritious supplement.
  • The most prevalent addition that contains it is a common salt.
  • It is accustomed to preventing iodine loss through salt oxidation.
  • It is employed to treat hyperthyroidism.
  • It aids in fostering hormonal harmony.
  • Chlorides, bromides, fluorides, and mercury are filtered out of cells and tissues.
  • As an expectorant, it breaks up mucus to make breathing easier for the patient.
  • It can aid in reducing the thyroid gland’s size and the number of thyroid hormones produced.

Effects of Iodide

KI can negatively impact health and trigger sensitivity. When KI is not taken exactly as prescribed by a doctor or public grownup, the chance of injury increases.

Among the negative consequences on health are:

  • Gastrointestinal (stomach) disturbances, rashes, and gland inflammation.
  • An allergic response.
  • Babies younger than a month old who receive more than one dosage of KI develop hypothyroidism. When the thyroid doesn’t generate enough hormones, the condition is known as hypothyroidism.
  • People taking more KI than is recommended risk developing serious illnesses or dying.
  • Vomiting, diarrhoea, abdominal pain, rash, and enlargement of the salivary glands are typical adverse effects. 
  • Allergic reactions, headaches, goitres, and depression are other side effects. Although use during pregnancy could harm the unborn child, it is nevertheless advised in cases of radiation emergencies.

Capacity of KI Use

  • KI can be harmful to a person if they come into contact with it without any prescription. If still, it’s mandatory to intake KI, the best time to take KI is before or after internal radioactive iodine contamination. The amount of radioactive iodine that enters the body and how rapidly it is absorbed affect KI’s effectiveness.
  • Only those under 40 and pregnant or nursing should use KI. People with specific medical concerns, such as known iodine sensitivity external icons, shouldn’t take KI or consult a healthcare professional to determine whether they can do so safely.

KI only provides a little amount of protection for particular circumstances and populations:

  • Only radioactive iodine is protected from KI; other forms of radiation are not protected.
  • KI only safeguards the thyroid. KI does not cover other body components.
  • KI must be taken within 24 hours or four hours to be most effective after exposure.
  • KI is not a remedy and cannot repair thyroid damage that has already occurred.
  • A person may not be completely protected from radioactive iodine by KI.
  • The majority of radiation emergencies will involve not only radioactive iodine but also other forms of radiation. Iodine is most frequently present in nuclear power plant accidents. The best defence in a radiation emergency is always to enter, remain inside, and pay attention to further announcements from authorities.

A compound derived from Potassium Iodide:

Potassium Iodate /Iodic Potassium (KIO3)

When potassium iodate comes into contact with combustible substances or reducing agents, which could lead to fires, it acts as an oxidizer. 

KIO3 is the chemical name or formula for potassium iodate. It will be made by mixing acid with potassium bases like KOH. The primary chemical accustomed to common ionising salts for human consumption is potassium iodate. It offers a practical method for winding up iodometric work. Thorium is occasionally precipitated using iodic potassium, particularly when it must be removed from the grouping elements. 

In a 1:1 ratio, K+ ions and IO3 ions structure the chemical molecule potassium iodate (KIO3) As an oxidising substance, iodic potassium can start fires when it comes into contact with flammable substances or reducing substances. A potassium-containing base like potash and acid are often combined to form it, as in:

HIO3 + KOH → KIO3 + H2O

Another way to make it is to mix iodine into a heated, concentrated solution of hydroxide.

3 I2 + 6 KOH → KIO3 + 5 KI + 3 H2O

Alternatively, the melt is extracted with water after being fused with iodide, salt, potassium bromate, or potassium perchlorate, and potassium iodate is crystallised to separate it from the solution:

KI + KClO3 → KIO3 + KCl

Properties of Iodic Potassium

  • Chemical Formula – KIO3
  • Density – 3.89 g/cm3
  • Boiling Point – 100 °C
  • Melting Point – 560 °C
  • Molecular mass of KIO3 – 214.001 g/mol

Potassium Iodate Formula– KIO3

Potassium Iodate formula

Frequently Asked Questions 

1. Why is iodide beneficial to the body?

Answer: A stable (non-radioactive) iodine salt called iodide (KI) can help safeguard the thyroid from radiation damage by preventing the endocrine from absorbing radioactive iodine. The part of the body most prone to radioactive iodine is the endocrine. 

2. What occurs after you consume potassium iodide?

Answer: Unless your doctor has advised differently, take iodide after meals, with food, or with milk if it irritates your stomach. Consult your doctor if you experience nausea, vomiting, abdominal pain, or diarrhoea after eating.

Iodic Potassium


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