Potassium iodide
You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.
| Potassium iodide | |
|---|---|
| |
| |
| IUPAC name | Potassium iodide |
| Other names | Kalium iodide, knollide, potide |
| Identifiers | |
| CAS number | |
| RTECS number | TT2975000 |
| Properties | |
| Molecular formula | KI |
| Molar mass | 166.00 g/mol |
| Appearance | white crystalline solid |
| Density | 3.13 g/cm3, solid |
| Melting point |
681 °C (954 K) |
| Boiling point |
1330 °C (1603 K) |
| Solubility in water | 128 g/100 ml (6 °C) |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | Slightly hazardous |
| NFPA 704 |
|
| R-phrases | R36, R38, R42-R43, R61 |
| S-phrases | S26, S36-S37, S39, S45 |
| Related Compounds | |
| Other anions | potassium bromide potassium chloride |
| Other cations | lithium iodide sodium iodide rubidium iodide caesium iodide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references | |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-525-6884
Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [2] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.
Potassium iodide is a white crystalline salt with chemical formula, used in photography and radiation treatment. It finds widespread application as an iodide source because it is less hygroscopic than sodium iodide, making it easier to work with. KI can turn yellow upon heating in air or upon standing in moist air for long periods, because of oxidation of the iodide to iodine.
Chemical properties
Potassium iodide behaves as a simple ionic salt, K+I−. Since the iodide ion is a mild reducing agent, I− is easily oxidised to I2 by powerful oxidising agents such as chlorine:
Even air will oxidize iodide as evidenced by the observation of a purple extract when KI is rinsed with dichloromethane. Under acidic conditions, KI is oxidised even more easily, due to the formation of hydroiodic acid (HI), which is a powerful reducing agent.[1][1][1][1]
KI forms I3− when combined with elemental iodine.
Unlike I2, I3− salts can be highly water-soluble. I2 and I3− have virtually identical redox potentials (0.535 and 0.536 V vs NHE, respectively), i.e. they are both mild oxidants relative to H2. Therefore, this reaction allows the iodine to be used in aqueous solutions for redox titrations.
Potassium iodide also serves in some organic reactions as a source of iodide ion (see "uses" below).
Physical Properties
It occurs as odourless, colourless, transparent or somewhat opaque crystals or white granular powder. It is slightly hygroscopic, the taste is saline and slightly bitter. On long exposure to air, it becomes yellow due to the liberation of iodine and small quantities of iodate may be formed.
Uses
Potassium iodide is used in photography, in the preparation of silver(I) iodide for high speed photographic film:
Potassium iodide is also added to table salt in small quantities to make it "iodized". In a saturated solution, it is also used as an expectorant to treat lung congestion.
KI is often used as a source of iodide ion in organic synthesis. A useful application is in the preparation of aryl iodides from arenediazonium salts.[1][1] For example:
Saturated solution of potassium iodide is also used as treatment for sporotrichosis, a fungal infection.
In medical use, it can also serve as an antiseptic for people suffering from sore throat. The dose is 0.5 g-1.0 g in 100 mL, with the accompany of iodine (0.5 g-1.0 g in 100 mL).
KI is also used as a fluorescence quenching agent in biomedical research because of collisional quenching by its iodide ion.
In aqueous solution with elemental iodine, it acts as a gold etchant and will attack and dissolve gold surfaces.
Radiation protection
Potassium iodide was also FDA approved in 1982 to protect the thyroid from radioactive iodine. In the event of an accident or attack at a nuclear power plant, or fallout from a nuclear bomb, several volatile fission product radionuclides may be released. 131I is a common fission by-product and is particularly dangerous as the body concentrates it only in the thyroid gland which may lead to thyroid cancer. By saturating the body with a source of stable iodine prior to exposure, any radioactive 131I inhaled or ingested becomes the excess in the blood system and is excreted through the kidneys. Potassium iodide cannot protect against any other causes of radiation poisoning, however, nor can it provide any degree of protection against a dirty bomb unless the bomb happens to contain a significant amount of radioactive iodine. In case of a nuclear emergency, iodine used for the cleaning of wounds should not be ingested, as it is poisonous. Only 3 brands of potassium iodide have been tested and approved for use by the FDA as a thyroid blocking agent during exposure to radioactive iodine (Iosat, ThyroShield and Thyro-safe) and hence potassium iodate is not approved in the U.S. for this purpose.
| Age | KI in mg | |
|---|---|---|
| Over 12 years old | 130 | |
| 3 - 12 years old | 65 | |
| 1 - 36 months old | 32 | |
| < 1 month old | 16 |
See fission products and the external links for more details.
Precautions
Mild irritant, wear gloves. Chronic overexposure can have adverse effects on the thyroid.
References
External links
Antidotes (V03AB) | |
|---|---|
| Methanol / Ethylene glycol | Ethanol - Fomepizole |
| Paracetamol (Acetaminophen) | Acetylcysteine - Glutathione - Methionine |
| Arsenic | Dimercaprol - Succimer |
| Cyanide | 4-Dimethylaminophenol - Amyl nitrite - Hydroxocobalamin - Sodium nitrite - Sodium thiosulfate |
| Heparin | Protamine |
| Nerve agent / Organophosphate pesticide | Atropine - Biperiden - Diazepam - Oximes (Pralidoxime, Obidoxime) - see also Cholinesterase |
| Opioid | Diprenorphine - Nalorphine - Naloxone - Naltrexone - Nalmefene |
| Benzodiazepine | Flumazenil |
| Toxic metals (Cadmium, Mercury, Lead etc) | Edetates - Dimercaprol |
| Other | Ipecacuanha - Prednisolone/promethazine - Methylthioninium chloride - Potassium permanganate - Physostigmine - Copper sulfate - Potassium iodide - Digoxin Immune Fab - Prussian blue |
de:Kaliumiodidit:Ioduro di potassio lv:Kālija jodīds hu:Kálium-jodid nl:Kaliumjodide ja:ヨウ化カリウム nn:Kaliumjodidsr:Калијум јодид sv:Kaliumjodid
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
