potassium#Nutrition

The English name for the element potassium comes from the word potash,{{cite journal|first=Humphry|last=Davy|title=On some new phenomena of chemical changes produced by electricity, in particular the decomposition of the fixed alkalies, and the exhibition of the new substances that constitute their bases; and on the general nature of alkaline bodies|page=32|year=1808|volume=98|journal=Philosophical Transactions of the Royal Society|url=https://books.google.com/books?id=gpwEAAAAYAAJ&pg=PA32|doi=10.1098/rstl.1808.0001|doi-access=free}} which refers to an early method of extracting various potassium salts: placing in a pot the ash of burnt wood or tree leaves, adding water, heating, and evaporating the solution. When Humphry Davy first isolated the pure element using electrolysis in 1807, he named it potassium, which he derived from the word potash.

The symbol K stems from kali, itself from the root word alkali, which in turn comes from {{langx|ar|القَلْيَه}} al-qalyah 'plant ashes'. In 1797, the German chemist Martin Klaproth discovered "potash" in the minerals leucite and lepidolite, and realized that "potash" was not a product of plant growth but actually contained a new element, which he proposed calling kali.Klaproth, M. (1797) "Nouvelles données relatives à l'histoire naturelle de l'alcali végétal" (New data regarding the natural history of the vegetable alkali), Mémoires de l'Académie royale des sciences et belles-lettres (Berlin), pp. 9–13 ; [https://babel.hathitrust.org/cgi/pt?id=mdp.39015073704093;view=1up;seq=103 see p. 13.] {{Webarchive|url=https://web.archive.org/web/20200124010707/https://babel.hathitrust.org/cgi/pt?id=mdp.39015073704093;view=1up;seq=103 |date=2020-01-24 }} From p. 13: "Cet alcali ne pouvant donc plus être envisagé comme un produit de la végétation dans les plantes, occupe une place propre dans la série des substances primitivement simples du règne minéral, &I il devient nécessaire de lui assigner un nom, qui convienne mieux à sa nature.

La dénomination de Potasche (potasse) que la nouvelle nomenclature françoise a consacrée comme nom de tout le genre, ne sauroit faire fortune auprès des chimistes allemands, qui sentent à quel point la dérivation étymologique en est vicieuse. Elle est prise en effet de ce qu'anciennement on se servoit pour la calcination des lessives concentrées des cendres, de pots de fer (pott en dialecte de la Basse-Saxe) auxquels on a substitué depuis des fours à calciner.

Je propose donc ici, de substituer aux mots usités jusqu'ici d'alcali des plantes, alcali végétal, potasse, &c. celui de kali, & de revenir à l'ancienne dénomination de natron, au lieu de dire alcali minéral, soude &c."

(This alkali [i.e., potash] — [which] therefore can no longer be viewed as a product of growth in plants — occupies a proper place in the originally simple series of the mineral realm, and it becomes necessary to assign it a name that is better suited to its nature.

The name of "potash" (potasse), which the new French nomenclature has bestowed as the name of the entire species [i.e., substance], would not find acceptance among German chemists, who feel to some extent [that] the etymological derivation of it is faulty. Indeed, it is taken from [the vessels] that one formerly used for the roasting of washing powder concentrated from cinders: iron pots (pott in the dialect of Lower Saxony), for which roasting ovens have been substituted since then.

Thus I now propose to substitute for the until now common words of "plant alkali", "vegetable alkali", "potash", etc., that of kali ; and to return to the old name of natron instead of saying "mineral alkali", "soda", etc.) In 1807, Humphry Davy produced the element via electrolysis: in 1809, Ludwig Wilhelm Gilbert proposed the name Kalium for Davy's "potassium".{{cite journal|author=Davy, Humphry |year=1809|title=Ueber einige neue Erscheinungen chemischer Veränderungen, welche durch die Electricität bewirkt werden; insbesondere über die Zersetzung der feuerbeständigen Alkalien, die Darstellung der neuen Körper, welche ihre Basen ausmachen, und die Natur der Alkalien überhaupt|trans-title=On some new phenomena of chemical changes that are achieved by electricity; particularly the decomposition of flame-resistant alkalis [i.e., alkalies that cannot be reduced to their base metals by flames], the preparation of new substances that constitute their [metallic] bases, and the nature of alkalies generally|journal=Annalen der Physik|volume=31|issue=2|pages=113–175|url=https://books.google.com/books?id=vyswAAAAYAAJ&pg=PA157|quote=p. 157: In unserer deutschen Nomenclatur würde ich die Namen Kalium und Natronium vorschlagen, wenn man nicht lieber bei den von Herrn Erman gebrauchten und von mehreren angenommenen Benennungen Kali-Metalloid and Natron-Metalloid, bis zur völligen Aufklärung der chemischen Natur dieser räthzelhaften Körper bleiben will. Oder vielleicht findet man es noch zweckmässiger fürs Erste zwei Klassen zu machen, Metalle und Metalloide, und in die letztere Kalium und Natronium zu setzen. — Gilbert. (In our German nomenclature, I would suggest the names Kalium and Natronium, if one would not rather continue with the appellations Kali-metalloid and Natron-metalloid which are used by Mr. Erman [i.e., German physics professor Paul Erman (1764–1851)] and accepted by several [people], until the complete clarification of the chemical nature of these puzzling substances. Or perhaps one finds it yet more advisable for the present to create two classes, metals and metalloids, and to place Kalium and Natronium in the latter — Gilbert.)|bibcode=1809AnP....31..113D|doi=10.1002/andp.18090310202}} In 1814, the Swedish chemist Berzelius advocated the name kalium for potassium, with the chemical symbol K.Berzelius, J. Jacob (1814) Försök, att, genom användandet af den electrokemiska theorien och de kemiska proportionerna, grundlägga ett rent vettenskapligt system för mineralogien [Attempt, by the use of electrochemical theory and chemical proportions, to found a pure scientific system for mineralogy]. Stockholm, Sweden: A. Gadelius., [https://archive.org/stream/bub_gb_Uw0-AAAAcAAJ#page/n91/mode/2up p. 87.]

The English and French-speaking countries adopted the name Potassium, which was favored by Davy and French chemists Joseph Louis Gay-Lussac and Louis Jacques Thénard, whereas the other Germanic countries adopted Gilbert and Klaproth's name Kalium.[http://www.vanderkrogt.net/elements/element.php?sym=K 19. Kalium (Potassium) – Elementymology & Elements Multidict] {{Webarchive|url=https://web.archive.org/web/20190218230851/http://vanderkrogt.net/elements/element.php?sym=K |date=2019-02-18 }}. vanderkrogt.net The "Gold Book" of the International Union of Pure and Applied Chemistry has designated the official chemical symbol as K.McNaught, A. D. and Wilkinson,A. eds. (1997). Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). IUPAC. Blackwell Scientific Publications, Oxford.

File:FlammenfärbungK.png of potassium.]]

Potassium is the second least dense metal after lithium. It is a soft solid with a low melting point, and can be easily cut with a knife. Potassium is silvery in appearance, but it begins to tarnish toward gray immediately on exposure to air.Greenwood, p. 76 In a flame test, potassium and its compounds emit a lilac color with a peak emission wavelength of 766.5 nanometers.Greenwood, p. 75

Neutral potassium atoms have 19 electrons, one more than the configuration of the noble gas argon. Because of its low first ionization energy of 418.8{{nbsp}}kJ/mol, the potassium atom is much more likely to lose the last electron and acquire a positive charge, although negatively charged alkalide {{chem2|K−}} ions are not impossible.{{cite journal|journal = Angewandte Chemie International Edition|year = 1979|last = Dye|first=J. L. |title = Compounds of Alkali Metal Anions|volume = 18|issue = 8|pages = 587–598|doi = 10.1002/anie.197905871}} In contrast, the second ionization energy is very high (3052{{nbsp}}kJ/mol).

Potassium reacts with oxygen, water, and carbon dioxide components in air. With oxygen it forms potassium peroxide. With water potassium forms potassium hydroxide (KOH). The reaction of potassium with water can be violently exothermic, especially since the coproduced hydrogen gas can ignite. Because of this, potassium and the liquid sodium-potassium (NaK) alloy are potent desiccants, although they are no longer used as such.{{cite journal|doi=10.1021/jo101589h|pmid=20945830|title=Drying of Organic Solvents: Quantitative Evaluation of the Efficiency of Several Desiccants|journal=The Journal of Organic Chemistry|volume=75|issue=24|pages=8351–8354|year=2010|last1=Williams|first1=D. Bradley G.|last2=Lawton|first2=Michelle|s2cid=17801540}}

Image:potassium-superoxide-unit-cell-3D-ionic.png

Four oxides of potassium are well studied: potassium oxide ({{chem2|K2O}}), potassium peroxide ({{chem2|K2O2}}), potassium superoxide ({{chem2|KO2}}){{cite book|last = Lide|first = David R.|date = 1998|title = Handbook of Chemistry and Physics|edition = 87th|location = Boca Raton, Florida, United States|publisher = CRC Press|isbn = 978-0-8493-0594-8|pages = 477; 520}} and potassium ozonide ({{chem2|KO3}}). The binary potassium-oxygen compounds react with water forming KOH.

KOH is a strong base. Illustrating its hydrophilic character, as much as 1.21 kg of KOH can dissolve in a single liter of water.{{RubberBible86th|page=4–80}}Schultz, p. 94 Anhydrous KOH is rarely encountered. KOH reacts readily with carbon dioxide ({{chem2|CO2}}) to produce potassium carbonate ({{chem2|K2CO3}}), and in principle could be used to remove traces of the gas from air. Like the closely related sodium hydroxide, KOH reacts with fats to produce soaps.

In general, potassium compounds are ionic and, owing to the high hydration energy of the {{chem2|K+}} ion, have excellent water solubility. The main species in water solution are the aquo complexes {{chem2|[K(H2O)_{n}]+}} where n = 6 and 7.Lincoln, S. F.; Richens, D. T. and Sykes, A. G. "Metal Aqua Ions" in J. A. McCleverty and T. J. Meyer (eds.) [https://www.sciencedirect.com/referencework/9780080437484/comprehensive-coordination-chemistry-ii Comprehensive Coordination Chemistry II] {{Webarchive|url=https://web.archive.org/web/20190419212906/https://www.sciencedirect.com/referencework/9780080437484/comprehensive-coordination-chemistry-ii |date=2019-04-19 }}, Vol. 1, pp. 515–555, {{ISBN|978-0-08-043748-4}}.

Potassium heptafluorotantalate ({{chem2|K2[TaF7]}}) is an intermediate in the purification of tantalum from the otherwise persistent contaminant of niobium.{{cite book|author=Anthony Agulyanski|editor=Anatoly Agulyanski|chapter=Fluorine chemistry in the processing of tantalum and niobium|title=Chemistry of Tantalum and Niobium Fluoride Compounds |year=2004 |publisher=Elsevier |location=Burlington |isbn=978-0-08-052902-8|edition=1st}}

Organopotassium compounds illustrate nonionic compounds of potassium. They feature highly polar covalent K–C bonds. Examples include benzyl potassium {{chem2|KCH2C6H5}}. Potassium intercalates into graphite to give a variety of graphite intercalation compounds, including {{chem2|KC8}}.

{{main|Isotopes of potassium}}

There are 25 known isotopes of potassium, three of which occur naturally: {{chem|39|K}} (93.3%), {{chem|40|K}} (0.0117%), and {{chem|41|K}} (6.7%) (by mole fraction). Naturally occurring potassium-40 has a half-life of {{val|1.250e9}} years. It decays to stable Argon by electron capture or positron emission (11.2%) or to stable Calcium by beta decay (88.8%).{{NUBASE 2003}} The decay of {{chem|40|K}} to {{chem|40|Ar}} is the basis of a common method for dating rocks. The conventional K-Ar dating method depends on the assumption that the rocks contained no argon at the time of formation and that all the subsequent radiogenic argon ({{chem|40|Ar}}) was quantitatively retained. Minerals are dated by measurement of the concentration of potassium and the amount of radiogenic {{chem|40|Ar}} that has accumulated. The minerals best suited for dating include biotite, muscovite, metamorphic hornblende, and volcanic feldspar; whole rock samples from volcanic flows and shallow instrusives can also be dated if they are unaltered.{{cite book|chapter-url = https://books.google.com/books?id=k90iAnFereYC&pg=PA207|pages =203–8|chapter= Theory and Assumptions in Potassium–Argon Dating|title = Isotopes in the Earth Sciences|isbn = 978-0-412-53710-3|last1 = Bowen|first1 = Robert|last2 = Attendorn|first2 = H. G.|date = 1988|publisher=Springer}} Apart from dating, potassium isotopes have been used as tracers in studies of weathering and for nutrient cycling studies because potassium is a macronutrient required for life{{cite book|author=Anaç, D.|author2=Martin-Prével, P.|title=Improved crop quality by nutrient management|url=https://books.google.com/books?id=9Hr4w6QhPGsC&pg=PA290|date=1999|publisher=Springer|isbn=978-0-7923-5850-3|pages=290–}} on Earth.

{{chem|40|K}} occurs in natural potassium (and thus in some commercial salt substitutes) in sufficient quantity that large bags of those substitutes can be used as a radioactive source for classroom demonstrations. {{chem|40|K}} is the radioisotope with the largest abundance in the human body. In healthy animals and people, {{chem|40|K}} represents the largest source of radioactivity, greater even than Carbon-14. In a human body of 70 kg, about 4,400 nuclei of {{chem|40|K}} decay per second.{{cite web|url=http://sciencedemonstrations.fas.harvard.edu/presentations/radioactive-human-body|title=Radiation and Radioactive Decay. Radioactive Human Body|access-date=July 2, 2016|publisher=Harvard Natural Sciences Lecture Demonstrations|archive-date=May 28, 2023|archive-url=https://web.archive.org/web/20230528120501/https://sciencedemonstrations.fas.harvard.edu/presentations/radioactive-human-body|url-status=live}} The activity of natural potassium is 31 Bq/g.{{cite book|url = https://books.google.com/books?id=KRVXMiQWi0cC&pg=PA32|page =32|title = Radioactive fallout in soils, crops and food: a background review|isbn = 978-92-5-102877-3|author1 = Winteringham, F. P. W|author2 = Effects, F.A.O. Standing Committee on Radiation, Land And Water Development Division, Food and Agriculture Organization of the United Nations|date = 1989|publisher=Food & Agriculture Org.}}

{{main|Potash}}

Potash is primarily a mixture of potassium salts because plants have little or no sodium content, and the rest of a plant's major mineral content consists of calcium salts of relatively low solubility in water. While potash has been used since ancient times, its composition was not understood. Georg Ernst Stahl obtained experimental evidence that led him to suggest the fundamental difference of sodium and potassium salts in 1702,{{cite book|url = https://books.google.com/books?id=b-ATAAAAQAAJ&pg=PA167|page = 167|title = Chymische Schriften|last1 = Marggraf|first1 = Andreas Siegmund|date = 1761}} and Henri Louis Duhamel du Monceau was able to prove this difference in 1736.{{cite journal|url = http://gallica.bnf.fr/ark:/12148/bpt6k3533j/f73.image.r=Memoires%20de%20l%27Academie%20royale%20des%20Sciences.langEN|journal = Mémoires de l'Académie Royale des Sciences|title = Sur la Base de Sel Marin|last = du Monceau|first = H. L. D.|pages = 65–68|language = fr|date = 1702–1797|access-date = 2011-05-09|archive-date = 2019-08-21|archive-url = https://web.archive.org/web/20190821202241/https://gallica.bnf.fr/ark%3A/12148/bpt6k3533j/f73.image.r%3DMemoires%20de%20l%27Academie%20royale%20des%20Sciences.langEN|url-status = live}} The exact chemical composition of potassium and sodium compounds, and the status as chemical element of potassium and sodium, was not known then, and thus Antoine Lavoisier did not include the alkali in his list of chemical elements in 1789.{{cite journal|doi = 10.1021/ed009p1035|title = The discovery of the elements. IX. Three alkali metals: Potassium, sodium, and lithium|year = 1932|last1 = Weeks|first1 = Mary Elvira|author-link1=Mary Elvira Weeks|journal = Journal of Chemical Education|volume = 9|issue = 6|pages = 1035|bibcode = 1932JChEd...9.1035W}}{{cite journal|jstor = 228541|pages = 247–258|last1 = Siegfried|first1 = R.|title = The Discovery of Potassium and Sodium, and the Problem of the Chemical Elements|volume = 54|issue = 2|journal = Isis|year = 1963|doi = 10.1086/349704|pmid = 14147904|s2cid = 38152048}} For a long time the only significant applications for potash were the production of glass, bleach, soap and gunpowder as potassium nitrate.{{cite journal|doi = 10.1021/ed003p749|title = Historical notes upon the domestic potash industry in early colonial and later times|year = 1926|last1 = Browne|first1 = C. A.|journal = Journal of Chemical Education|volume = 3|issue = 7|pages = 749–756|bibcode = 1926JChEd...3..749B}} Potassium soaps from animal fats and vegetable oils were especially prized because they tend to be more water-soluble and of softer texture, and are therefore known as soft soaps. The discovery by Justus Liebig in 1840 that potassium is a necessary element for plants and that most types of soil lack potassium{{cite book|url = https://archive.org/details/dieorganischech01liebgoog|title = Die organische Chemie in ihrer Anwendung auf Agricultur und Physiologie|publisher = F. Vieweg und Sohn|author = Liebig, Justus von|date = 1840| language = de}} caused a steep rise in demand for potassium salts. Wood-ash from fir trees was initially used as a potassium salt source for fertilizer, but, with the discovery in 1868 of mineral deposits containing potassium chloride near Staßfurt, Germany, the production of potassium-containing fertilizers began at an industrial scale.{{cite book|author=Cordel, Oskar |title=Die Stassfurter Kalisalze in der Landwirthschalt: Eine Besprechung ...|url=https://books.google.com/books?id=EYpIAAAAYAAJ|date=1868|publisher=L. Schnock| language = de}}{{cite book|url = https://books.google.com/books?id=J8Q6AAAAcAAJ|title = Die Kalidüngung in ihren Vortheilen und Gefahren|last1 = Birnbaum| first1= Karl|date = 1869| language = de}}{{cite book|url = https://books.google.com/books?id=qPkoOU4BvEsC&pg=PA417|title = Fertilizer Manual|isbn = 978-0-7923-5032-3|author = United Nations Industrial Development Organization and Int'l Fertilizer Development Center|date = 1998|pages=46, 417| publisher=Springer }} Other potash deposits were discovered, and by the 1960s Canada became the dominant producer.{{cite journal|jstor = 3103338|pages = 187–208|last1 = Miller|first1 = H.|title = Potash from Wood Ashes: Frontier Technology in Canada and the United States|volume = 21|issue = 2|journal = Technology and Culture|year = 1980|doi=10.2307/3103338| s2cid=112819807 }}{{cite journal|doi = 10.2113/gsecongeo.74.2.353|title = Potash and politics|year = 1979|last1 = Rittenhouse|first1 = P. A.|journal = Economic Geology|volume = 74|issue = 2|pages = 353–7| bibcode=1979EcGeo..74..353R }}

File:Sir Humphry Davy, Bt by Thomas Phillips.jpg ]]

File:Potassium.JPG

Potassium metal was first isolated in 1807 by Humphry Davy, who derived it by electrolysis of molten caustic potash (KOH) with the newly discovered voltaic pile. Potassium was the first metal that was isolated by electrolysis.{{cite book|last=Enghag|first= P.|date=2004|url=https://archive.org/details/encyclopediaofel0000engh| title=Encyclopedia of the elements| publisher=Wiley-VCH Weinheim| isbn=978-3-527-30666-4| chapter=11. Sodium and Potassium}} Later in the same year, Davy reported extraction of the metal sodium from a mineral derivative (caustic soda, NaOH, or lye) rather than a plant salt, by a similar technique, demonstrating that the elements, and thus the salts, are different.{{cite journal|first=Humphry|last=Davy|title=On some new phenomena of chemical changes produced by electricity, in particular the decomposition of the fixed alkalies, and the exhibition of the new substances that constitute their bases; and on the general nature of alkaline bodies|pages=1–44|year=1808|volume=98|journal=Philosophical Transactions of the Royal Society|url=https://books.google.com/books?id=gpwEAAAAYAAJ&pg=PA57|doi=10.1098/rstl.1808.0001|doi-access=free}}{{cite journal|doi = 10.1134/S1061934807110160|title = History of the discovery of potassium and sodium (on the 200th anniversary of the discovery of potassium and sodium)|year = 2007|last1 = Shaposhnik|first1 = V. A.|journal = Journal of Analytical Chemistry|volume = 62|issue = 11|pages = 1100–2|s2cid = 96141217}} Although the production of potassium and sodium metal should have shown that both are elements, it took some time before this view was universally accepted.

Because of the sensitivity of potassium to water and air, air-free techniques are normally employed for handling the element. It is unreactive toward nitrogen and saturated hydrocarbons such as mineral oil or kerosene.{{cite book|publisher = Walter de Gruyter|date = 1985|edition = 91–100|isbn = 978-3-11-007511-3|title = Lehrbuch der Anorganischen Chemie|first1 = Arnold F.|last1 = Holleman|last2 = Wiberg|first2 = Egon|last3 = Wiberg|first3 = Nils|chapter = Potassium| language = de}} It readily dissolves in liquid ammonia, up to 480 g per 1000 g of ammonia at 0{{nbsp}}°C. Depending on the concentration, the ammonia solutions are blue to yellow, and their electrical conductivity is similar to that of liquid metals. Potassium slowly reacts with ammonia to form Potassium amide, but this reaction is accelerated by minute amounts of transition metal salts.Burkhardt, p. 32 Because it can reduce the salts to the metal, potassium is often used as the reductant in the preparation of finely divided metals from their salts by the Rieke method.{{cite journal| author=Rieke, R. D.|title=Preparation of Organometallic Compounds from Highly Reactive Metal Powders|journal= Science|year= 1989|volume= 246| pages= 1260–4|doi=10.1126/science.246.4935.1260| pmid=17832221| issue=4935|bibcode = 1989Sci...246.1260R |s2cid=92794}} Illustrative is the preparation of magnesium:

:{{chem2|MgCl2 + 2 K → Mg + 2 KCl}}

File:PotassiumFeldsparUSGOV.jpg]]

Potassium is formed in supernovae by nucleosynthesis from lighter atoms. Potassium is principally created in Type II supernovae via an explosive oxygen-burning process.{{cite journal|first1= V.|last1= Shimansky|title=Observational constraints on potassium synthesis during the formation of stars of the Galactic disk| journal=Astronomy Reports|date=September 2003|bibcode = 2003ARep...47..750S|last2= Bikmaev|first2=I. F.|last3= Galeev|first3=A. I.|last4= Shimanskaya|first4=N. N.|last5= Ivanova|first5=D. V.|last6= Sakhibullin|first6=N. A.|last7= Musaev|first7=F. A.|last8= Galazutdinov|first8=G. A.|volume= 47|pages= 750–762|doi= 10.1134/1.1611216|issue= 9|s2cid= 120396773}} These are nuclear fusion reactions, not to be confused with chemical burning of potassium in oxygen. {{chem|40|K}} is also formed in {{Nowrap|s-process}} nucleosynthesis and the neon burning process.{{cite journal|last1=The|first1=L.-S.|last2=Eid|first2=M. F. El|last3=Meyer|first3=B. S.|date=2000|title=A New Study of s-Process Nucleosynthesis in Massive Stars|journal=The Astrophysical Journal|volume=533|issue=2|pages=998|doi=10.1086/308677|issn=0004-637X|arxiv=astro-ph/9812238|bibcode=2000ApJ...533..998T|s2cid=7698683}}

Potassium is the 20th most abundant element in the Solar System and the 17th most abundant element by weight in the Earth. It makes up about 2.6% of the weight of the Earth's crust and is the seventh most abundant element in the crust.Greenwood, p. 69 The potassium concentration in seawater is 0.39{{nbsp}}g/L (0.039 wt/v%), about one twenty-seventh the concentration of sodium.{{cite book|url = https://books.google.com/books?id=NXEmcGHScV8C&pg=PA3| publisher = Springer| date = 2009|title = Seawater Desalination: Conventional and Renewable Energy Processes|first1= Giorgio |last1=Micale| first2=Andrea |last2=Cipollina| first3=Lucio |last3=Rizzuti|page = 3| isbn = 978-3-642-01149-8}}{{cite book|chapter-url = https://books.google.com/books?id=zNicdkuulE4C&pg=PA723| title =Industrial minerals & rocks: commodities, markets, and uses|publisher = Society for Mining, Metallurgy, and Exploration|date= 2006| first1= Michel|last1=Prud'homme|first2= Stanley T.| last2 = Krukowski|chapter = Potash|pages = 723–740|isbn = 978-0-87335-233-8}}

Elemental potassium does not occur in nature because of its high reactivity. It reacts violently with water and also reacts with oxygen. Orthoclase (potassium feldspar) is a common rock-forming mineral. Granite for example contains 5% potassium, which is well above the average in the Earth's crust. Sylvite (KCl), carnallite ({{chem2|KCl*MgCl2*6H2O}}), kainite ({{chem2|MgSO4*KCl*3H2O}}) and langbeinite ({{chem2|MgSO4*K2SO4}}) are the minerals found in large evaporite deposits worldwide. The deposits often show layers starting with the least soluble at the bottom and the most soluble on top. Deposits of niter (potassium nitrate) are formed by decomposition of organic material in contact with atmosphere, mostly in caves; because of the good water solubility of niter the formation of larger deposits requires special environmental conditions.{{cite book|chapter-url = https://books.google.com/books?id=NyUDAAAAMBAJ&pg=PA134|pages = 134–145| chapter = The Origin of Nitrate Deposits| first = William H.| last = Ross|title = Popular Science|date = 1914|publisher=Bonnier Corporation}}

File:Museo de La Plata - Silvita.jpg from New Mexico]]

File:Wintershall Monte Kali 12.jpg, a potash mining and beneficiation waste heap in Hesse, Germany, consisting mostly of sodium chloride.]]

Potassium salts such as carnallite, langbeinite, polyhalite, and sylvite form extensive evaporite deposits in ancient lake bottoms and seabeds, making extraction of potassium salts in these environments commercially viable. The principal source of potassium – potash – is mined in Canada, Russia, Belarus, Kazakhstan, Germany, Israel, the U.S., Jordan, and other places around the world.{{cite book|url = https://books.google.com/books?id=EHx51n3T858C|publisher=Springer|title = Potash: deposits, processing, properties and uses|isbn = 978-0-412-99071-7|last1 = Garrett|first1= Donald E.|date = 1995-12-31}}{{cite web|url=http://minerals.usgs.gov/minerals/pubs/commodity/potash/mcs-2008-potas.pdf|first=Joyce A.|last=Ober|publisher=United States Geological Survey|title=Mineral Commodity Summaries 2008:Potash|access-date=2008-11-20|archive-date=2019-01-11|archive-url=https://web.archive.org/web/20190111170532/https://minerals.usgs.gov/minerals/pubs/commodity/potash/mcs-2008-potas.pdf|url-status=live}}{{cite web|url=https://minerals.usgs.gov/minerals/pubs/commodity/potash/myb1-2006-potas.pdf|first=Joyce A.|last=Ober|publisher=United States Geological Survey|title=Mineral Yearbook 2006:Potash|access-date=2008-11-20|archive-date=2008-12-17|archive-url=https://web.archive.org/web/20081217043522/http://minerals.usgs.gov/minerals/pubs/commodity/potash/myb1-2006-potas.pdf|url-status=live}} The first mined deposits were located near Staßfurt, Germany, but the deposits span from Great Britain over Germany into Poland. They are located in the Zechstein and were deposited in the Middle to Late Permian. The largest deposits ever found lie {{convert|1000|m|ft|abbr=off|sp=us}} below the surface of the Canadian province of Saskatchewan. The deposits are located in the Elk Point Group produced in the Middle Devonian. Saskatchewan, where several large mines have operated since the 1960s pioneered the technique of freezing of wet sands (the Blairmore formation) to drive mine shafts through them. The main potash mining company in Saskatchewan until its merge was the Potash Corporation of Saskatchewan, now Nutrien.{{cite book|url = https://books.google.com/books?id=rtRFyFO4hpEC&pg=PA433|publisher=U of Nebraska Press|page = 433|title = Encyclopedia of the Great Plains|isbn = 978-0-8032-4787-1|author1-link=David J. Wishart|last = Wishart| first=David J.|date = 2004}} The water of the Dead Sea is used by Israel and Jordan as a source of potash, while the concentration in normal oceans is too low for commercial production at current prices.

Several methods are used to separate potassium salts from sodium and magnesium compounds. The most-used method is fractional precipitation using the solubility differences of the salts. Electrostatic separation of the ground salt mixture is also used in some mines. The resulting sodium and magnesium waste is either stored underground or piled up in slag heaps. Most of the mined potassium mineral ends up as potassium chloride after processing. The mineral industry refers to potassium chloride either as potash, muriate of potash, or simply MOP.

Pure potassium metal can be isolated by electrolysis of its hydroxide in a process that has changed little since it was first used by Humphry Davy in 1807. Although the electrolysis process was developed and used in industrial scale in the 1920s, the thermal method by reacting sodium with potassium chloride in a chemical equilibrium reaction became the dominant method in the 1950s.

:Na + KCl → NaCl + K

The production of sodium potassium alloys is accomplished by changing the reaction time and the amount of sodium used in the reaction. The Griesheimer process employing the reaction of potassium fluoride with calcium carbide was also used to produce potassium.{{cite book|doi=10.1002/0471238961.1615200103080921.a01.pub2|isbn= 978-0-471-23896-6

|last1=Chiu|first1=Kuen-Wai

|publisher=John Wiley & Sons, Inc.

|title=Kirk-Othmer Encyclopedia of Chemical Technology

|date=2000

|chapter= Potassium

}}

:{{chem2|2 KF + CaC2 → 2 K + CaF2 + 2 C}}

Reagent-grade potassium metal costs about $10.00/pound ($22/kg) in 2010 when purchased by the tonne. Lower purity metal is considerably cheaper. The market is volatile because long-term storage of the metal is difficult. It must be stored in a dry inert gas atmosphere or anhydrous mineral oil to prevent the formation of a surface layer of potassium superoxide, a pressure-sensitive explosive that detonates when scratched. The resulting explosion often starts a fire difficult to extinguish.Burkhardt, p. 34{{cite journal|doi =10.1016/j.jchas.2006.09.010|title =Review of the safety of potassium and potassium oxides, including deactivation by introduction into water|year =2007|last1 =Delahunt|first1 = J.|last2 =Lindeman|first2 = T.|journal =Journal of Chemical Health and Safety|volume =14|issue =2|pages =21–32}}

Potassium is now quantified by ionization techniques, but at one time it was quantitated by gravimetric analysis.

Reagents used to precipitate potassium salts include sodium tetraphenylborate, hexachloroplatinic acid, and sodium cobaltinitrite into respectively potassium tetraphenylborate, potassium hexachloroplatinate, and potassium cobaltinitrite.

The reaction with sodium cobaltinitrite is illustrative:

:{{chem2|3 K+ + Na3[Co(NO2)6] → K3[Co(NO2)6] + 3 Na+}}

The potassium cobaltinitrite is obtained as a yellow solid.

File:Patentkali (Potassium sulfate with magnesium).jpg

Potassium ions are an essential component of plant nutrition and are found in most soil types. They are used as a fertilizer in agriculture, horticulture, and hydroponic culture in the form of chloride (KCl), sulfate ({{chem2|K2SO4}}), or nitrate ({{chem2|KNO3}}), representing the 'K' in 'NPK'. Agricultural fertilizers consume 95% of global potassium chemical production, and about 90% of this potassium is supplied as KCl. The potassium content of most plants ranges from 0.5% to 2% of the harvested weight of crops, conventionally expressed as amount of {{chem2|K2O}}. Modern high-yield agriculture depends upon fertilizers to replace the potassium lost at harvest. Most agricultural fertilizers contain potassium chloride, while potassium sulfate is used for chloride-sensitive crops or crops needing higher sulfur content. The sulfate is produced mostly by decomposition of the complex minerals kainite ({{chem2|MgSO4*KCl*3H2O}}) and langbeinite ({{chem2|MgSO4*K2SO4}}). Only a very few fertilizers contain potassium nitrate.{{cite book|pages = 1135–57|first = Amit H. |last = Roy| url = https://books.google.com/books?id=AYjFoLCNHYUC&pg=PA1135|isbn = 978-0-387-27843-8|publisher=Springer|title = Kent and Riegel's handbook of industrial chemistry and biotechnology|date = 2007|bibcode = 2007karh.book...... }} In 2005, about 93% of world potassium production was consumed by the fertilizer industry. Furthermore, potassium can play a key role in nutrient cycling by controlling litter composition.{{cite journal |last1=Ochoa-Hueso |first1=R |last2=Delgado-Baquerizo |first2=M |last3=King |first3=PTA |last4=Benham |first4=M |last5=Arca |first5=V |last6=Power |first6=SA |title=Ecosystem type and resource quality are more important than global change drivers in regulating early stages of litter decomposition |journal=Soil Biology and Biochemistry |date=2019 |volume=129 |pages=144–152 |doi=10.1016/j.soilbio.2018.11.009 |bibcode=2019SBiBi.129..144O |s2cid=92606851 |hdl=10261/336676 |hdl-access=free }}

Potassium citrate is used to treat a kidney stone condition called renal tubular acidosis.{{cite web |title=Potassium Uses, Side Effects & Interactions |url=https://www.drugs.com/potassium.html |website=Drugs.com |language=en |access-date=2022-04-30 |archive-date=2022-04-30 |archive-url=https://web.archive.org/web/20220430065805/https://www.drugs.com/potassium.html |url-status=live }}

{{see also|Potassium chloride (medical use)}}

Potassium, in the form of potassium chloride is used as a medication to treat and prevent low blood potassium.{{cite book | title = WHO Model Formulary 2008 | year = 2009 | isbn = 978-92-4-154765-9 | vauthors = ((World Health Organization)) | veditors = Stuart MC, Kouimtzi M, Hill SR | hdl = 10665/44053 | author-link = World Health Organization | publisher = World Health Organization |page=491 }} Low blood potassium may occur due to vomiting, diarrhea, or certain medications.{{cite web|title=Potassium chloride medical facts from Drugs.com|url=https://www.drugs.com/mtm/potassium-chloride.html|website=www.drugs.com|access-date=14 January 2017|url-status=live|archive-url=https://web.archive.org/web/20170118040410/https://www.drugs.com/mtm/potassium-chloride.html|archive-date=18 January 2017}} It is given by slow injection into a vein or by mouth.{{cite book|title=British national formulary : BNF 69|date=2015|publisher=British Medical Association|isbn=978-0-85711-156-2|pages=680, 684|edition=69}}

Potassium sodium tartrate ({{chem2|KNaC4H4O6}}, Rochelle salt) is a main constituent of some varieties of baking powder; it is also used in the silvering of mirrors. Potassium bromate ({{chem2|KBrO3}}) is a strong oxidizer (E924), used to improve dough strength and rise height. Potassium bisulfite ({{chem2|KHSO3}}) is used as a food preservative, for example in wine and beer-making (but not in meats). It is also used to bleach textiles and straw, and in the tanning of leathers.{{cite book|chapter-url = https://books.google.com/books?id=XqKF7PqV02cC&pg=PA86|page = 86|chapter = Bleaching and Maturing Agents|title = How Baking Works: Exploring the Fundamentals of Baking Science|isbn = 978-0-470-39267-6|author = Figoni, Paula I|date= 2010|publisher=John Wiley and Sons}}{{cite book|chapter-url = https://books.google.com/books?id=eblAtwEXffcC&pg=PA4|publisher=Academic Press|pages = 4–6| chapter = Uses and Exposure to Sulfites in Food|title = Advances in food research|isbn = 978-0-12-016430-1|author = Chichester, C. O.|date = July 1986}}

Major potassium chemicals are potassium hydroxide, potassium carbonate, potassium sulfate, and potassium chloride. Megatons of these compounds are produced annually.Schultz

KOH is a strong base, which is used in industry to neutralize strong and weak acids, to control pH and to manufacture potassium salts. It is also used to saponify fats and oils, in industrial cleaners, and in hydrolysis reactions, for example of esters.{{cite book|publisher = Greenwood Publishing Group|chapter-url = https://books.google.com/books?id=UnjD4aBm9ZcC&pg=PA4|chapter = Personal Cleansing Products: Bar Soap|title = Chemical composition of everyday products|isbn = 978-0-313-32579-3|author = Toedt, John|author2 = Koza, Darrell|author3 = Cleef-Toedt, Kathleen Van|date = 2005|url-access = registration|url = https://archive.org/details/chemicalcomposit0000toed}}Schultz, p. 95

Potassium nitrate ({{chem2|KNO3}}) or saltpeter is obtained from natural sources such as guano and evaporites or manufactured via the Haber process; it is the oxidant in gunpowder (black powder) and an important agricultural fertilizer. Potassium cyanide (KCN) is used industrially to dissolve copper and precious metals, in particular silver and gold, by forming complexes. Its applications include gold mining, electroplating, and electroforming of these metals; it is also used in organic synthesis to make nitriles. Potassium carbonate ({{chem2|K2CO3}} or potash) is used in the manufacture of glass, soap, color TV tubes, fluorescent lamps, textile dyes and pigments.Schultz, p. 99 Potassium permanganate ({{chem2|KMnO4}}) is an oxidizing, bleaching and purification substance and is used for production of saccharin. Potassium chlorate ({{chem2|KClO3}}) is added to matches and explosives. Potassium bromide (KBr) was formerly used as a sedative and in photography.

While potassium chromate ({{chem2|K2CrO4}}) is used in the manufacture of a host of different commercial products such as inks, dyes, wood stains (by reacting with the tannic acid in wood), explosives, fireworks, fly paper, and safety matches,{{cite journal|doi = 10.1021/ed017p515|title = Ignition of the safety match|year = 1940|last1 = Siegel|first1 = Richard S.|journal = Journal of Chemical Education|volume = 17|issue = 11|pages = 515|bibcode = 1940JChEd..17..515S}} as well as in the tanning of leather, all of these uses are due to the chemistry of the chromate ion rather than to that of the potassium ion.{{Ullmann|contribution=Chromium Compounds|doi=10.1002/14356007.a07_067|volume=9|page=178|first1=Gerd|last1=Anger|first2=Jost|last2=Halstenberg|first3=Klaus|last3=Hochgeschwender|first4=Christoph|last4=Scherhag|first5=Ulrich|last5=Korallus|first6=Herbert|last6=Knopf|first7=Peter|last7=Schmidt|first8=Manfred|last8=Ohlinger}}

There are thousands of uses of various potassium compounds. One example is potassium superoxide, {{chem2|KO2}}, an orange solid that acts as a portable source of oxygen and a carbon dioxide absorber. It is widely used in respiration systems in mines, submarines and spacecraft as it takes less volume than the gaseous oxygen.Greenwood, p. 74{{cite book|url = https://archive.org/details/historyofunderwa00marx|url-access = registration|title = The history of underwater exploration|first = Robert F. |last = Marx|publisher =Courier Dover Publications| date = 1990|isbn = 978-0-486-26487-5|page=[https://archive.org/details/historyofunderwa00marx/page/93 93]}}

:{{chem2|4 KO2 + 2 CO2 → 2 K2CO3 + 3 O2}}

Another example is potassium cobaltinitrite, {{chem2|K3[Co(NO2)6]}}, which is used as artist's pigment under the name of Aureolin or Cobalt Yellow.{{cite book|publisher = Courier Dover Publications|url = https://books.google.com/books?id=bdQVgKWl3f4C&pg=PA109|title = Painting materials: A short encyclopaedia|isbn = 978-0-486-21597-6|author = Gettens, Rutherford John|author2 = Stout, George Leslie|date = 1966|pages = 109–110|access-date = 2016-01-08|archive-date = 2023-01-19|archive-url = https://web.archive.org/web/20230119031503/https://books.google.com/books?id=bdQVgKWl3f4C&pg=PA109|url-status = live}}

The stable isotopes of potassium can be laser cooled and used to probe fundamental and technological problems in quantum physics. The two bosonic isotopes possess convenient Feshbach resonances to enable studies requiring tunable interactions, while {{chem|40|K}} is one of only two stable fermions amongst the alkali metals.{{cite journal|last1=Modugno|first1=G.|last2=Benkő|first2=C.|last3=Hannaford|first3=P.|last4=Roati|first4=G.|last5=Inguscio|first5=M.|date=1999-11-01|title=Sub-Doppler laser cooling of fermionic ${}^{40}\mathrm{K}$ atoms|journal=Physical Review A|volume=60|issue=5|pages=R3373–R3376|doi=10.1103/PhysRevA.60.R3373|arxiv=cond-mat/9908102|bibcode=1999PhRvA..60.3373M|s2cid=119001675}}

An alloy of sodium and potassium, NaK is a liquid used as a heat-transfer medium and a desiccant for producing dry and air-free solvents. It can also be used in reactive distillation.{{cite book |doi=10.1021/ba-1957-0019.ch018|volume=19 |isbn=978-0-8412-0020-3 |chapter=Ch. 18: The Manufacture of Potassium and NaK |pages=169–173 |last2=Werner |first2=R. C. |last1=Jackson |first1=C. B. |year=1957 |title=Handling and uses of the alkali metals |series=Advances in Chemistry}} The ternary alloy of 12% Na, 47% K and 41% Cs has the lowest melting point of −78{{nbsp}}°C of any metallic compound.

Metallic potassium is used in several types of magnetometers.{{cite book|publisher=Wiley-Blackwell|chapter-url =https://books.google.com/books?id=R_Y925b97ncC&pg=PA164|chapter = Optical Pumped Magnetometer|pages = 164|title =An introduction to geophysical exploration|isbn =978-0-632-04929-5|author =Kearey, Philip|author2 =Brooks, M|author3 =Hill, Ian|date =2002}}

{{Main|Potassium in biology}}

Potassium is the eighth or ninth most common element by mass (0.2%) in the human body, so that a 60{{nbsp}}kg adult contains a total of about 120{{nbsp}}g of potassium.{{cite journal|doi = 10.1016/0883-2889(92)90208-V|title = A simple calibration of a whole-body counter for the measurement of total body potassium in humans|year = 1992|last1 = Abdel-Wahab|first1 = M.|last2 = Youssef|first2 = S.|last3 = Aly|first3 = A.|last4 = el-Fiki|first4 = S.|last5 = el-Enany|first5 = N.|last6 = Abbas|first6 = M.|journal = International Journal of Radiation Applications and Instrumentation A|volume = 43|issue = 10|pages = 1285–9|pmid=1330980}} The body has about as much potassium as sulfur and chlorine, and only calcium and phosphorus are more abundant (with the exception of the ubiquitous CHON elements).{{cite book|author=Chang, Raymond |title=Chemistry|url=https://books.google.com/books?id=huSDQAAACAAJ|date= 2007|publisher=McGraw-Hill Higher Education|isbn=978-0-07-110595-8|page=52}} Potassium ions are present in a wide variety of proteins and enzymes.{{cite book|first1= Milan |last1= Vašák|first2= Joachim |last2= Schnabl|publisher= Springer|date= 2016|series= Metal Ions in Life Sciences|volume=16|title= The Alkali Metal Ions: Their Role in Life|editor1-last=Astrid|editor1-first= Sigel|editor2-last=Helmut|editor2-first=Sigel|editor3-last=Roland K.O.|editor3-first= Sigel|chapter= Chapter 8. Sodium and Potassium Ions in Proteins and Enzyme Catalysis |pages= 259–290

|doi=10.1007/978-3-319-21756-7_8|pmid= 26860304|isbn= 978-3-319-21755-0}} Potassium is largely intracellular.{{Cite journal |last=Zacchia |first=Miriam |last2=Abategiovanni |first2=Maria Luisa |last3=Stratigis |first3=Spiros |last4=Capasso |first4=Giovambattista |date=2016 |title=Potassium: From Physiology to Clinical Implications |url=https://karger.com/KDD/article/doi/10.1159/000446268 |journal=Kidney Diseases |language=en |volume=2 |issue=2 |pages=72–79 |doi=10.1159/000446268 |issn=2296-9381|pmc=4947686 }}

Potassium levels influence multiple physiological processes, including{{cite book|vauthors=Weiner ID, Linus S, Wingo CS|chapter= Disorders of potassium metabolism|veditors= Freehally J, Johnson RJ, Floege J|title= Comprehensive clinical nephrology|edition= 5th |place=St. Louis|publisher= Saunders|year= 2014|pages=118|isbn= 978-0-323-24287-5 }}{{cite book|vauthors=Malnic G, Giebisch G, Muto S, Wang W, Bailey MA, Satlin LM|chapter= Regulation of K+ excretion|veditors= Alpern RJ, Caplan MJ, Moe OW|title=Seldin and Giebisch's the kidney: physiology and pathophysiology|edition= 5th |place= London|publisher= Academic Press|year= 2013|pages=1659–1716|isbn=978-0-12-381463-0 }}{{cite book |vauthors=Mount DB, Zandi-Nejad K |chapter=Disorders of potassium balance |veditors= Taal MW, Chertow GM, Marsden PA, Skorecki KL, Yu AS, Brenner BM |title=The kidney |edition= 9th |place= Philadelphia |publisher= Elsevier |year= 2011 |pages=640–688 |isbn=978-1-4557-2304-1 }}

• resting cellular-membrane potential and the propagation of action potentials in neuronal, muscular, and cardiac tissue. Due to the electrostatic and chemical properties, {{chem2|K+}} ions are larger than {{chem2|Na+}} ions, and ion channels and pumps in cell membranes can differentiate between the two ions, actively pumping or passively passing one of the two ions while blocking the other.{{cite journal|pmid=17472437|title=Structural and thermodynamic properties of selective ion binding in a K+ channel|last1=Lockless |first1 = S. W.| last2= Zhou|first2 =M.|last3= MacKinnon|first3 =R.|journal=PLOS Biol|year= 2007 |volume=5|issue=5|page=e121|doi=10.1371/journal.pbio.0050121|pmc=1858713 |doi-access=free }}
• hormone secretion and action
• vascular tone
• systemic blood pressure control
• gastrointestinal motility
• acid–base homeostasis
• glucose and insulin metabolism
• mineralocorticoid action
• renal concentrating ability
• fluid and electrolyte balance
• local cortical monoaminergic norepinephrine, serotonin, and dopamine levels, and through them, sleep/wake balance, and spontaneous activity.{{cite journal |last1=Dietz |first1=Andrea Grostøl |last2=Weikop |first2=Pia |last3=Hauglund |first3=Natalie |last4=Andersen |first4=Mie |last5=Petersen |first5=Nicolas Caesar |last6=Rose |first6=Laura |last7=Hirase |first7=Hajime |last8=Nedergaard |first8=Maiken |date=2023 |title=Local extracellular K ⁺ in cortex regulates norepinephrine levels, network state, and behavioral output |journal=Proceedings of the National Academy of Sciences |volume=120 |issue=40 |page=e2305071120 |doi=10.1073/pnas.2305071120 |issn=0027-8424|doi-access=free |pmid=37774097 |pmc=10556678 |bibcode=2023PNAS..12005071D }}

Potassium homeostasis denotes the maintenance of the total body potassium content, plasma potassium level, and the ratio of the intracellular to extracellular potassium concentrations within narrow limits, in the face of pulsatile intake (meals), obligatory renal excretion, and shifts between intracellular and extracellular compartments.

Plasma potassium is normally kept at 3.5 to 5.5 millimoles (mmol) [or milliequivalents (mEq)] per liter by multiple mechanisms.{{cite journal | last1=Wei | first1=Kuang-Yu | last2=Gritter | first2=Martin | last3=Vogt | first3=Liffert | last4=de Borst | first4=Martin H | last5=Rotmans | first5=Joris I | last6=Hoorn | first6=Ewout J | title=Dietary potassium and the kidney: lifesaving physiology | journal=Clinical Kidney Journal | publisher=Oxford University Press (OUP) | volume=13 | issue=6 | date=2020-09-02 | issn=2048-8513 | pmid=33391739 | pmc=7769543 | doi=10.1093/ckj/sfaa157 | pages=952–968}} Levels outside this range are associated with an increasing rate of death from multiple causes,{{cite journal | last1 = Goyal | first1 = Abhinav | last2 = Spertus | first2 = John A. | last3 = Gosch | first3 = Kensey | last4 = Venkitachalam | first4 = Lakshmi | last5 = Jones | first5 = Philip G. | last6 = Van den Berghe | first6 = Greet | last7 = Kosiborod | first7 = Mikhail | year = 2012 | title = Serum Potassium Levels and Mortality in Acute Myocardial Infarction | journal = JAMA | volume = 307 | issue = 2| pages = 157–164 | doi = 10.1001/jama.2011.1967 | pmid = 22235086 | doi-access = free }} and some cardiac, kidney,{{cite journal | last1 = Smyth | first1 = A. | last2 = Dunkler | first2 = D. | last3 = Gao | first3 = P. | display-authors = etal | year = 2014 | title = The relationship between estimated sodium and potassium excretion and subsequent renal outcomes | journal = Kidney Int | volume = 86 | issue = 6| pages = 1205–1212 | doi=10.1038/ki.2014.214| pmid = 24918156 | doi-access = free }} and lung diseases progress more rapidly if serum potassium levels are not maintained within the normal range.

An average meal of 40–50{{nbsp}}mmol presents the body with more potassium than is present in all plasma (20–25{{nbsp}}mmol). This surge causes the plasma potassium to rise up to 10% before clearance by renal and extrarenal mechanisms.{{cite journal | last1 = Moore-Ede | first1 = M. C. | year = 1986 | title = Physiology of the circadian timing system: predictive versus reactive homeostasis | journal = Am J Physiol | volume = 250 | issue = 5 Pt 2| pages = R737–R752 | doi = 10.1152/ajpregu.1986.250.5.R737 | pmid = 3706563 }}

Hypokalemia, a deficiency of potassium in the plasma, can be fatal if severe. Common causes are increased gastrointestinal loss (vomiting, diarrhea), and increased renal loss (diuresis).{{cite book|publisher=Lippincott Williams & Wilkins|chapter-url = https://books.google.com/books?id=_XavFllbnS0C&pg=PA812|page = 812| chapter = Potassium|title = Pediatric critical care medicine|isbn = 978-0-7817-9469-5|last1 = Slonim|first1= Anthony D.|last2 = Pollack|first2= Murray M.|date = 2006}} Deficiency symptoms include muscle weakness, paralytic ileus, ECG abnormalities, decreased reflex response; and in severe cases, respiratory paralysis, alkalosis, and cardiac arrhythmia.{{cite book |chapter-url = https://books.google.com/books?id=c4xAdJhIi6oC&pg=PT257 |page =257|chapter = hypokalemia |title = Essentials of Nephrology|edition=2nd|publisher=BI Publications |isbn = 978-81-7225-323-3 |last1 = Visveswaran |first1= Kasi |date = 2009}}

Potassium content in the plasma is tightly controlled by four basic mechanisms, which have various names and classifications. These are:

1. a reactive negative-feedback system,
2. a reactive feed-forward system,
3. a predictive or circadian system, and
4. an internal or cell membrane transport system.

Collectively, the first three are sometimes termed the "external potassium homeostasis system";{{cite journal |last1=Gumz |first1=Michelle L. |last2=Rabinowitz |first2=Lawrence |last3=Wingo |first3=Charles S. |date=2015-07-02 |title=An Integrated View of Potassium Homeostasis |journal=The New England Journal of Medicine |volume=373 |issue=1 |pages=60–72 |doi=10.1056/NEJMra1313341 |issn=0028-4793 |pmc=5675534 |pmid=26132942}} and the first two, the "reactive potassium homeostasis system".

• The reactive negative-feedback system refers to the system that induces renal secretion of potassium in response to a rise in the plasma potassium (potassium ingestion, shift out of cells, or intravenous infusion.)
• The reactive feed-forward system refers to an incompletely understood system that induces renal potassium secretion in response to potassium ingestion prior to any rise in the plasma potassium. This is probably initiated by gut cell potassium receptors that detect ingested potassium and trigger vagal afferent signals to the pituitary gland.
• The predictive or circadian system increases renal secretion of potassium during mealtime hours (e.g. daytime for humans, nighttime for rodents) independent of the presence, amount, or absence of potassium ingestion. It is mediated by a circadian oscillator in the suprachiasmatic nucleus of the brain (central clock), which causes the kidney (peripheral clock) to secrete potassium in this rhythmic circadian fashion.File:Scheme sodium-potassium pump-en.svg is an example of primary active transport. The two carrier proteins embedded in the cell membrane on the left are using ATP to move sodium out of the cell against the concentration gradient; The two proteins on the right are using secondary active transport to move potassium into the cell. This process results in reconstitution of ATP.]]
• The ion transport system moves potassium across the cell membrane using two mechanisms. One is active and pumps sodium out of, and potassium into, the cell. The other is passive and allows potassium to leak out of the cell. Potassium and sodium cations influence fluid distribution between intracellular and extracellular compartments by osmotic forces. The movement of potassium and sodium through the cell membrane is mediated by the Na⁺/K⁺-ATPase pump.{{cite book|last=Campbell|first=Neil|title=Biology|date=1987|isbn=978-0-8053-1840-1|page=795|publisher=Benjamin/Cummings Pub. Co.|location=Menlo Park, California}} This ion pump uses ATP to pump three sodium ions out of the cell and two potassium ions into the cell, creating an electrochemical gradient and electromotive force across the cell membrane. The highly selective potassium ion channels (which are tetramers) are crucial for hyperpolarization inside neurons after an action potential is triggered, to cite one example. The most recently discovered potassium ion channel is KirBac3.1, which makes a total of five potassium ion channels (KcsA, KirBac1.1, KirBac3.1, KvAP, and MthK) with a determined structure. All five are from prokaryotic species.{{cite journal|first1=Mikko |last1 = Hellgren| first2= Lars |last2= Sandberg|first3= Olle |last3= Edholm|title=A comparison between two prokaryotic potassium channels (K_irBac1.1 and KcsA) in a molecular dynamics (MD) simulation study|journal=Biophysical Chemistry| volume=120|issue=1|pages=1–9|year=2006|pmid=16253415|doi=10.1016/j.bpc.2005.10.002}}

Renal handling of potassium is closely connected to sodium handling. Potassium is the major cation (positive ion) inside animal cells (150{{nbsp}}mmol/L, 4.8{{nbsp}}g/L), while sodium is the major cation of extracellular fluid (150{{nbsp}}mmol/L, 3.345{{nbsp}}g/L). In the kidneys, about 180{{nbsp}}liters of plasma is filtered through the glomeruli and into the renal tubules per day.{{cite book |author=Potts, W. T. W. |author2=Parry, G. |date=1964 |title=Osmotic and ionic regulation in animals |publisher=Pergamon Press}} This filtering involves about 600{{nbsp}}mg of sodium and 33{{nbsp}}mg of potassium. Since only 1–10{{nbsp}}mg of sodium and 1–4{{nbsp}}mg of potassium are likely to be replaced by diet, renal filtering must efficiently reabsorb the remainder from the plasma.

Sodium is reabsorbed to maintain extracellular volume, osmotic pressure, and serum sodium concentration within narrow limits. Potassium is reabsorbed to maintain serum potassium concentration within narrow limits.{{cite journal |last1=Lans |first1=H. 's. |last2= Stein |first2=I. F. |last3= Meyer |first3=K. A. |title=The relation of serum potassium to erythrocyte potassium in normal subjects and patients with potassium deficiency |journal=American Journal of the Medical Sciences |volume=223 |issue=1 |pages=65–74 |year=1952| pmid=14902792 |doi=10.1097/00000441-195201000-00011}} Sodium pumps in the renal tubules operate to reabsorb sodium. Potassium must be conserved, but because the amount of potassium in the blood plasma is very small and the pool of potassium in the cells is about 30 times as large, the situation is not so critical for potassium. Since potassium is moved passively{{cite journal |last1=Bennett |first1=C. M. |last2= Brenner |first2=B. M. |last3= Berliner |first3=R. W. |title=Micropuncture study of nephron function in the rhesus monkey |journal=Journal of Clinical Investigation |volume=47 |issue=1 |pages=203–216 |year=1968 |pmid=16695942 |doi=10.1172/JCI105710 |pmc=297160}}{{cite journal |last1=Solomon |first1=A. K. |title=Pumps in the living cell |journal=Scientific American| volume=207 |pages=100–8 |year=1962 |pmid=13914986 |doi=10.1038/scientificamerican0862-100 |issue=2 |bibcode=1962SciAm.207b.100S}} in counter flow to sodium in response to an apparent (but not actual) Donnan equilibrium,{{cite book |last=Kernan |first= Roderick P. |title=Cell potassium (Transport in the life sciences) |publisher=Wiley |location=New York |date=1980 |pages=40, 48 |isbn= 978-0-471-04806-0}} the urine can never sink below the concentration of potassium in serum except sometimes by actively excreting water at the end of the processing. Potassium is excreted twice and reabsorbed three times before the urine reaches the collecting tubules.{{cite journal |last1=Wright |first1=F. 's. |title=Sites and mechanisms of potassium transport along the renal tubule |journal=Kidney International |volume=11 |issue=6 |pages=415–432 |year=1977 |pmid=875263 |doi=10.1038/ki.1977.60 |doi-access=free}} At that point, urine usually has about the same potassium concentration as plasma. At the end of the processing, potassium is secreted one more time if the serum levels are too high.{{citation needed|date=August 2017}}

With no potassium intake, it is excreted at about 200{{nbsp}}mg per day until, in about a week, potassium in the serum declines to a mildly deficient level of 3.0–3.5{{nbsp}}mmol/L.{{cite journal |last1=Squires |first1=R. D. |last2= Huth |first2 = E. J. |title=Experimental potassium depletion in normal human subjects. I. Relation of ionic intakes to the renal conservation of potassium |journal=Journal of Clinical Investigation |volume=38 |issue=7 |pages=1134–48 |year=1959 |pmid=13664789 |doi=10.1172/JCI103890 |pmc=293261}} If potassium is still withheld, the concentration continues to fall until a severe deficiency causes eventual death.{{cite book |author=Fiebach, Nicholas H. |author2=Barker, Lee Randolph |author3=Burton, John Russell |author4=Zieve, Philip D.|title=Principles of ambulatory medicine |url=https://books.google.com/books?id=UGVylX6g4i8C&pg=PA748 |date=2007 |publisher=Lippincott Williams & Wilkins |isbn=978-0-7817-6227-4 |pages=748–750}}

The potassium moves passively through pores in the cell membrane. When ions move through ion transporters (pumps) there is a gate in the pumps on both sides of the cell membrane and only one gate can be open at once. As a result, approximately 100 ions are forced through per second. Ion channels have only one gate, and there only one kind of ion can stream through, at 10 million to 100 million ions per second.{{cite journal |last=Gadsby |first=D. C. |title=Ion transport: spot the difference |journal=Nature |volume=427 |issue=6977 |pages=795–7 |year=2004 |pmid=14985745 |doi=10.1038/427795a |bibcode = 2004Natur.427..795G |s2cid=5923529}}; for a diagram of the potassium pores are viewed, see {{cite journal |author=Miller, C |title=See potassium run |journal=Nature |volume=414 |issue=6859 |pages=23–24 |year=2001 |pmid=11689922 |doi=10.1038/35102126 |bibcode = 2001Natur.414...23M |s2cid=4423041 }} Calcium is required to open the pores,{{cite journal |last1=Jiang |first1=Y. |last2=Lee |first2=A. |last3=Chen |first3=J. |last4=Cadene |first4=M. |last5=Chait |first5=B. 't. |last6=Mackinnon |first6=R. |url=http://einstein.ciencias.uchile.cl/CursoTroncal2007/Biblio/Jiang__MacKinnonNature417_515_2002.pdf |title=Crystal structure and mechanism of a calcium-gated potassium channel |journal=Nature |volume=417 |issue=6888 |pages=515–22 |year=2002 |pmid=12037559 |doi=10.1038/417515a |bibcode=2002Natur.417..515J |s2cid=205029269 |url-status=dead |archive-url=https://web.archive.org/web/20090424074015/http://einstein.ciencias.uchile.cl/CursoTroncal2007/Biblio/Jiang__MacKinnonNature417_515_2002.pdf |archive-date=2009-04-24 |s2cid-access=free }} although calcium may work in reverse by blocking at least one of the pores.{{cite journal |last1=Shi |first1=N. |last2= Ye |first2=S. |last3= Alam |first3=A. |last4= Chen |first4=L. |last5= Jiang |first5=Y. |title=Atomic structure of a Na⁺- and K⁺-conducting channel |journal=Nature |volume=440 |issue=7083 |pages=570–4 |year=2006 |pmid=16467789 |doi=10.1038/nature04508 |bibcode =2006Natur.440..570S |s2cid=4355500 |postscript=;}} includes a detailed picture of atoms in the pump. Carbonyl groups inside the pore on the amino acids mimic the water hydration that takes place in water solution{{cite journal |last1=Zhou |first1=Y. |last2= Morais-Cabral |first2=J. H. |last3= Kaufman |first3=A. |last4= MacKinnon |first4=R. |title=Chemistry of ion coordination and hydration revealed by a K⁺ channel-Fab complex at 2.0 A resolution |journal=Nature |volume=414 |issue=6859 |pages=43–48 |year=2001 |pmid=11689936 |doi=10.1038/35102009 |bibcode = 2001Natur.414...43Z |s2cid=205022645 |url=http://www.acsu.buffalo.edu/~moralesm/Zhou.pdf |url-status=dead |archive-url=https://web.archive.org/web/20211017203255/http://www.acsu.buffalo.edu/~moralesm/Zhou.pdf |archive-date= Oct 17, 2021 }} by the nature of the electrostatic charges on four carbonyl groups inside the pore.{{cite journal|last1=Noskov |first1=S. Y. |last2= Bernèche |first2=S. |last3= Roux |first3=B. |title=Control of ion selectivity in potassium channels by electrostatic and dynamic properties of carbonyl ligands |journal=Nature |volume=431 |issue=7010 |pages=830–4 |year=2004 |pmid=15483608 |doi=10.1038/nature02943 |bibcode =2004Natur.431..830N |s2cid=4414885 |s2cid-access=free |url=https://www.physics.uci.edu/~tritz/BP/ionchannel.pdf |url-status=live |archive-url=https://web.archive.org/web/20230326185426/https://www.physics.uci.edu/~tritz/BP/ionchannel.pdf |archive-date= Mar 26, 2023 }}

The U.S. National Academy of Medicine (NAM), on behalf of both the U.S. and Canada, sets Dietary Reference Intakes, including Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs), or Adequate Intakes (AIs) for when there is not sufficient information to set EARs and RDAs.

For both males and females under 9 years of age, the AIs for potassium are: 400{{nbsp}}mg of potassium for 0 to 6-month-old infants, 860{{nbsp}}mg of potassium for 7 to 12-month-old infants, 2,000{{nbsp}}mg of potassium for 1 to 3-year-old children, and 2,300{{nbsp}}mg of potassium for 4 to 8-year-old children.

For males 9 years of age and older, the AIs for potassium are: 2,500{{nbsp}}mg of potassium for 9 to 13-year-old males, 3,000{{nbsp}}mg of potassium for 14 to 18-year-old males, and 3,400{{nbsp}}mg for males that are 19 years of age and older.

For females 9 years of age and older, the AIs for potassium are: 2,300{{nbsp}}mg of potassium for 9 to 18-year-old females, and 2,600{{nbsp}}mg of potassium for females that are 19 years of age and older.

For pregnant and lactating females, the AIs for potassium are: 2,600{{nbsp}}mg of potassium for 14 to 18-year-old pregnant females, 2,900{{nbsp}}mg for pregnant females that are 19 years of age and older; furthermore, 2,500{{nbsp}}mg of potassium for 14 to 18-year-old lactating females, and 2,800{{nbsp}}mg for lactating females that are 19 years of age and older. As for safety, the NAM also sets tolerable upper intake levels (ULs) for vitamins and minerals, but for potassium the evidence was insufficient, so no UL was established.{{cite book |author=National Academies of Sciences, Engineering and Medicine |editor3-first=Maria |editor3-last=Oria |editor2-first=Meghan |editor2-last=Harrison |editor1-first=Virginia A |editor1-last=Stallings |date=2019 |title=Dietary Reference Intakes for Sodium and Potassium |location=Washington, DC |publisher=The National Academies Press |chapter=Potassium: Dietary Reference Intakes for Adequacy |chapter-url=https://www.nap.edu/read/25353/chapter/8 |isbn=978-0-309-48834-1 |doi=10.17226/25353 |doi-access=free |pmid=30844154 |access-date=2019-05-13 |archive-date=2019-05-13 |archive-url=https://web.archive.org/web/20190513200758/https://www.nap.edu/read/25353/chapter/8 |url-status=live }}{{cite book |url=http://www.nationalacademies.org/hmd/Reports/2019/dietary-reference-intakes-sodium-potassium.aspx |title=Dietary Reference Intakes for Sodium and Potassium – Publication |date=March 5, 2019 |website=Health and Medicine Division |publisher=National Academies of Sciences, Engineering and Medicine |doi=10.17226/25353 |pmid=30844154 |isbn=978-0-309-48834-1 |s2cid=104464967 |access-date=May 13, 2019 |editor1-last=Stallings |editor1-first=Virginia A |editor2-first=Meghan |editor2-last=Harrison |editor3-first=Maria |editor3-last=Oria |archive-date=May 9, 2019 |archive-url=https://web.archive.org/web/20190509031658/http://www.nationalacademies.org/hmd/Reports/2019/dietary-reference-intakes-sodium-potassium.aspx |url-status=live }}

As of 2004, most Americans adults consume less than 3,000{{nbsp}}mg.{{cite book|author=Panel on Dietary Reference Intakes for Electrolytes and Water, Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition|title=DRI, dietary reference intakes for water, potassium, sodium, chloride, and sulfate|date=2004|publisher=National Academies Press|location=Washington, D.C.|isbn=978-0-309-53049-1|url=http://www.iom.edu/Reports/2004/Dietary-Reference-Intakes-Water-Potassium-Sodium-Chloride-and-Sulfate.aspx|url-status=dead|archive-url=https://web.archive.org/web/20111006174858/http://www.iom.edu/Reports/2004/Dietary-Reference-Intakes-Water-Potassium-Sodium-Chloride-and-Sulfate.aspx|archive-date=2011-10-06}}

Likewise, in the European Union, in particular in Germany, and Italy, insufficient potassium intake is somewhat common.{{cite journal|last=Karger|first=S.|journal=Annals of Nutrition and Metabolism|year=2004|volume=48|issue=2 (suppl) |pages=1–16 |title=Energy and nutrient intake in the European Union|doi=10.1159/000083041|doi-access=free}}

The National Health Service in the United Kingdom recommends a similar intake, saying that "adults (19 to 64 years) need {{val|3500|u=mg}} per day" and that excess amounts may cause health problems such as stomach pain and diarrhea.{{cite web | title=Vitamins and minerals | website=National Health Service (NHS) | date=18 November 2021 | url=https://www.nhs.uk/conditions/vitamins-and-minerals/others/ | access-date=13 November 2022 | archive-date=3 April 2019 | archive-url=https://web.archive.org/web/20190403142101/https://www.nhs.uk/conditions/vitamins-and-minerals/others/ | url-status=live }}

Potassium is present in all fruits, vegetables, meat and fish. Foods with high potassium concentrations include yam, parsley, dried apricots, milk, chocolate, all nuts (especially almonds and pistachios), potatoes, bamboo shoots, bananas, avocados, coconut water, soybeans, and bran.{{cite web| url = http://apjcn.nhri.org.tw/server/info/books-phds/books/foodfacts/html/data/data5b.html|title = Potassium Food Charts|publisher =Asia Pacific Journal of Clinical Nutrition|access-date = 2011-05-18|archive-url=https://web.archive.org/web/20210429215547/http://apjcn.nhri.org.tw/server/info/books-phds/books/foodfacts/html/data/data5b.html|archive-date=2021-04-29}}

The United States Department of Agriculture also lists tomato paste, orange juice, beet greens, white beans, plantains, and many other dietary sources of potassium, ranked in descending order according to potassium content. A day's worth of potassium is in 5 plantains or 11 bananas.{{cite news|title=Potassium Content of Selected Foods per Common Measure, sorted by nutrient content |publisher=USDA National Nutrient Database for Standard Reference, Release 20 |url=http://www.nal.usda.gov/fnic/foodcomp/Data/SR20/nutrlist/sr20w306.pdf |url-status=dead |archive-url=https://web.archive.org/web/20081217043521/http://www.nal.usda.gov/fnic/foodcomp/Data/SR20/nutrlist/sr20w306.pdf |archive-date=December 17, 2008 }}

{{main|Hypokalemia}}

Mild hypokalemia does not cause distinct symptoms acting instead as a risk factor for hypertension{{cite journal |vauthors=Whelton PK, He J, Cutler JA, Brancati FL, Appel LJ, Follmann D, Klag MJ |title=Effects of oral potassium on blood pressure. Meta-analysis of randomized controlled clinical trials |journal=JAMA |volume=277 |issue=20 |pages=1624–32 |year=1997 |pmid=9168293 |doi=10.1001/jama.1997.03540440058033 |s2cid=25937399 }}{{cite journal | last1 = Krishna | first1 = GG | last2 = Miller | first2 = E | last3 = Kapoor | first3 = S | title = Increased blood pressure during potassium depletion in normotensive men | journal = The New England Journal of Medicine | volume = 320 | issue = 18 | pages = 1177–82 | year = 1989 | pmid = 2624617| doi = 10.1056/NEJM198905043201804 }} and cardiac arrhythmia.{{cite journal|last1=Soar| first1=J|last2=Perkins|first2=GD| last3=Abbas|first3=G|last4=Alfonzo|first4=A|last5=Barelli| first5=A|last6=Bierens|first6=JJ| last7=Brugger|first7=H|last8=Deakin|first8=CD|last9=Dunning|first9=J|last10=Georgiou|first10=M| last11=Handley|first11=AJ|last12=Lockey| first12=DJ|last13=Paal|first13=P|last14=Sandroni|first14=C| last15=Thies|first15=KC|last16=Zideman|first16=DA|last17=Nolan|first17=JP|title=European Resuscitation Council Guidelines for Resuscitation 2010 Section 8. Cardiac arrest in special circumstances: Electrolyte abnormalities, poisoning, drowning, accidental hypothermia, hyperthermia, asthma, anaphylaxis, cardiac surgery, trauma, pregnancy, electrocution.|journal=Resuscitation|date=October 2010| volume=81|issue=10|pages=1400–33|pmid=20956045| doi=10.1016/j.resuscitation.2010.08.015}}

Severe hypokalemia usually presents with hypertension, arrhythmia, muscle cramps, fatigue, weakness and constipation.

Causes of hypokalemia include vomiting, diarrhea, medications like furosemide and steroids, dialysis, diabetes insipidus, hyperaldosteronism, hypomagnesemia.

Supplements of potassium are most widely used in conjunction with diuretics that block reabsorption of sodium and water upstream from the distal tubule (thiazides and loop diuretics), because this promotes increased distal tubular potassium secretion, with resultant increased potassium excretion.{{Cite journal |last1=Horisberger |first1=Jean-Daniel |last2=Giebisch |first2=Gerhard |date=1987 |title=Potassium-Sparing Diuretics |url=https://karger.com/KBR/article/doi/10.1159/000173130 |journal=Kidney and Blood Pressure Research |language=en |volume=10 |issue=3–4 |pages=198–220 |doi=10.1159/000173130 |pmid=2455308 |issn=1420-4096 |archive-date=2024-07-12 |access-date=2024-07-19 |archive-url=https://web.archive.org/web/20240712015613/https://karger.com/KBR/article/doi/10.1159/000173130 |url-status=dead }} A variety of prescription and over-the counter supplements are available.{{Cite web |last1=Ng |first1=Kimberly |last2=Lee |first2=Chung-Shie |date=February 16, 2017 |title=Updated Treatment Options in the Management of Hyperkalemia |url=https://www.uspharmacist.com/article/updated-treatment-options-in-the-management-of-hyperkalemia |access-date=2024-07-19 |website=US Pharmacist |language=en}} Potassium chloride may be dissolved in water, but the salty/bitter taste makes liquid supplements unpalatable.{{Cite journal |last1=Benge |first1=Cassandra D. |last2=Burka |first2=Abigail T. |date=2020 |title=Oral Liquid Potassium Chloride Dosing Pathway in a Tertiary Care Veteran Affairs Academic Medical Center |url=https://journals.lww.com/10.1097/HPC.0000000000000197 |journal=Critical Pathways in Cardiology: A Journal of Evidence-Based Medicine |language=en |volume=19 |issue=1 |pages=18–21 |doi=10.1097/HPC.0000000000000197 |pmid=31478945 |issn=1535-282X}} Potassium is also available in tablets or capsules, which are formulated to allow potassium to leach slowly out of a matrix, since very high concentrations of potassium ion that occur adjacent to a solid tablet can injure the gastric or intestinal mucosa.{{Cite journal |last1=Gueta |first1=Itai |last2=Markovits |first2=Noa |last3=Halkin |first3=Hillel |last4=Loebstein |first4=Ronen |date=2021 |title=Concomitant oral potassium chloride and anticholinergic therapy is associated with upper gastrointestinal bleeding: A cohort study |url=https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/bcp.14616 |journal=British Journal of Clinical Pharmacology |language=en |volume=87 |issue=4 |pages=2064–2069 |doi=10.1111/bcp.14616 |pmid=33068044 |issn=0306-5251}} For this reason, non-prescription potassium pills are limited by law in the US to a maximum of 99{{nbsp}}mg of potassium.{{Cite web |date=June 2, 2022 |title=Potassium - Fact Sheet for Health Professionals |url=https://ods.od.nih.gov/factsheets/Potassium-HealthProfessional/ |access-date=2024-07-19 |website=National Institutes of Health (NIH) Office of Dietary Supplements (ODS) |language=en}}

Potassium supplementation can also be combined with other metabolites, such as citrate or chloride, to achieve specific clinical effects.{{cite journal |vauthors=Keller CL, Jones NT, Abadie RB, Barham W, Behara R, Patil S, Paladini A, Ahmadzadeh S, Shekoohi S, Varrassi G, Kaye AD |title=Non-steroidal Anti-inflammatory Drug (NSAID)-, Potassium Supplement-, Bisphosphonate-, and Doxycycline-Mediated Peptic Ulcer Effects: A Narrative Review |journal=Cureus |volume=16 |issue=1 |pages=e51894 |date=January 2024 |pmid=38333496 |pmc=10849936 |doi=10.7759/cureus.51894 |doi-access=free |url=}}

Potassium supplements may be employed to mitigate the impact of hypertension, thereby reducing cardiovascular risk.{{cite journal |last1=D'Elia |first1=L. |last2=Barba |first2=G. |last3=Cappuccio |first3=F. |last4=Strazzullo |year=2011 |title=Potassium Intake, Stroke, and Cardiovascular Disease: A Meta-Analysis of Prospective Studies |journal=J Am Coll Cardiol |volume=57 |issue=10 |pages=1210–9 |doi=10.1016/j.jacc.2010.09.070 |pmid=21371638|doi-access=free }} Potassium chloride and potassium bicarbonate may be useful to control mild hypertension.{{cite journal |vauthors=He FJ, Marciniak M, Carney C, Markandu ND, Anand V, Fraser WD, Dalton RN, Kaski JC, MacGregor GA |title=Effects of potassium chloride and potassium bicarbonate on endothelial function, cardiovascular risk factors, and bone turnover in mild hypertensives |journal=Hypertension |volume=55 |issue=3 |pages=681–8 |year=2010 |pmid=20083724 |doi=10.1161/HYPERTENSIONAHA.109.147488 |doi-access=free }} In 2020, potassium was the 33rd most commonly prescribed medication in the U.S., with more than 17{{nbsp}}million prescriptions.{{cite web |title=The Top 300 of 2020 |url=https://clincalc.com/DrugStats/Top300Drugs.aspx |website=ClinCalc |access-date=7 October 2022 |archive-date=12 February 2021 |archive-url=https://web.archive.org/web/20210212142534/https://clincalc.com/DrugStats/Top300Drugs.aspx |url-status=live }}{{cite web | title=Potassium Chloride - Drug Usage Statistics | website=ClinCalc | url=https://clincalc.com/DrugStats/Drugs/PotassiumChloride | access-date=7 October 2022 | archive-date=8 October 2022 | archive-url=https://web.archive.org/web/20221008035439/https://clincalc.com/DrugStats/Drugs/PotassiumChloride | url-status=live }} Potassium supplementation has been shown to reduce both systolic and diastolic blood pressure in individuals with essential hypertension.

Additionally, potassium supplements may be employed with the aim of preventing the formation of kidney stones, a condition that can lead to renal complications if left untreated. Low potassium levels can lead to decreased calcium reabsorption in the kidneys, increasing the risk of elevated urine calcium and the formation of kidney stones. By maintaining adequate potassium levels, this risk can be reduced.

The mechanism of action of potassium involves various types of transporters and channels that facilitate its movement across cell membranes. This process can lead to an increase in the pumping of hydrogen ions. This, in turn, can escalate the production of gastric acid, potentially contributing to the development of gastric ulcers.

Potassium has a role in bone health. It contributes to the acid-base equilibrium in the body and helps protect bone tissue. Potassium salts produce an alkaline component that can aid in maintaining bone health.

For individuals with diabetes, potassium supplementation may be necessary, particularly for those with type 2 diabetes. Potassium is essential for the secretion of insulin by pancreatic beta cells, which helps regulate glucose levels. Without sufficient potassium, insulin secretion is compromised, leading to hyperglycemia and worsening diabetes.

Excessive potassium intake can have adverse effects, such as gastrointestinal discomfort and disturbances in heart rhythm.

Potassium supplementation can have side effects on ulceration, particularly in relation to peptic ulcer disease. Potassium channels have the potential to increase gastric acid secretion, which can lead to an increased risk of ulcerations. Medications used for peptic ulcer disease, known as "proton pump inhibitors", work by inhibiting potassium pumps that activate the H/K ATPase. This inhibition helps to reduce the secretion of hydrochloric acid into the parietal cell, thereby decreasing acidic synthesis and lowering the risk of ulcers. Nicorandil, a drug used for the treatment of ischemic heart disease, can stimulate nitrate and potassium ATP channels, and as a result, it has been associated with side effects such as GI, oral, and anal ulcers. Potassium chloride tablets are specifically associated with pill esophagitis.{{Cite journal |last=Abdi |first=Saeed |last2=Masbough |first2=Farnoosh |last3=Nazari |first3=Maryam |last4=Abbasinazari |first4=Mohammad |date=2022-06-20 |title=Drug-induced esophagitis and helpful management for healthcare providers |url=https://doi.org/10.22037/ghfbb.v15i3.2591 |journal=Gastroenterology and Hepatology from Bed to Bench |volume=15 |issue=3 |doi=10.22037/ghfbb.v15i3.2591 |issn=2008-4234 |pmc=9589134 |pmid=36311965}} Prolonged and chronic use of potassium supplements has been linked to more severe side effects, including ulcers outside of the gastrointestinal (GI) tract. Close monitoring is necessary for patients who are also taking angiotensinogen-converting enzyme inhibitors, angiotensin receptor blockers, or potassium-sparing diuretics.

Potassium can be detected by taste because it triggers three of the five types of taste sensations, according to concentration. Dilute solutions of potassium ions taste sweet, allowing moderate concentrations in milk and juices, while higher concentrations become increasingly bitter/alkaline, and finally also salty to the taste. The combined bitterness and saltiness of high-potassium solutions makes high-dose potassium supplementation by liquid drinks a palatability challenge.{{cite book|author1=Institute of Medicine (U.S.). Committee on Optimization of Nutrient Composition of Military Rations for Short-Term, High-Stress Situations|author2=Institute of Medicine (U.S.). Committee on Military Nutrition Research|title=Nutrient composition of rations for short-term, high-intensity combat operations|url=https://books.google.com/books?id=kFatoIBbMboC&pg=PT287|date=2006|publisher=National Academies Press|isbn=978-0-309-09641-6|pages=287–}}{{cite book|last=Shallenberger|first=R. S. |title=Taste chemistry|url=https://books.google.com/books?id=8_bjyjgClq0C&pg=PA120|date=1993|publisher=Springer|isbn=978-0-7514-0150-9|pages=120–}} As a food additive, potassium chloride has a salty taste. People wishing to increase their potassium intake or to decrease their sodium intake, after checking with a health professional that it is safe to do so, can substitute potassium chloride for some or all of the sodium chloride (table salt) used in cooking and at the table.{{Cite journal |last=Tsai |first=Yi-Ching |last2=Tsao |first2=Yen-Po |last3=Huang |first3=Chi-Jung |last4=Tai |first4=Yen-Hsuan |last5=Su |first5=Yang-Chin |last6=Chiang |first6=Chern-En |last7=Sung |first7=Shih-Hsien |last8=Chen |first8=Chen-Huan |last9=Cheng |first9=Hao-Min |date=2022 |title=Effectiveness of salt substitute on cardiovascular outcomes: A systematic review and meta-analysis |url=https://onlinelibrary.wiley.com/doi/10.1111/jch.14562 |journal=The Journal of Clinical Hypertension |language=en |volume=24 |issue=9 |pages=1147–1160 |doi=10.1111/jch.14562 |issn=1751-7176 |pmc=9532913 |pmid=36196475}}

{{Chembox

| container_only = yes

|Section7={{Chembox Hazards

| ExternalSDS =

| GHSPictograms = {{GHS02}}{{GHS05}}

| GHSSignalWord = Danger

| HPhrases = {{H-phrases|260|314}}

| PPhrases = {{P-phrases|223|231+232|280|305+351+338|370+378|422}}{{cite web | url=https://www.sigmaaldrich.com/catalog/product/aldrich/244856?lang=en®ion=US | title=Potassium 244856 | publisher=Sigma Aldrich | access-date=2018-10-01 | archive-date=2018-10-01 | archive-url=https://web.archive.org/web/20181001103958/https://www.sigmaaldrich.com/catalog/product/aldrich/244856?lang=en®ion=US | url-status=live }}

| NFPA-H = 3

| NFPA-F = 3

| NFPA-R = 2

| NFPA-S = w

| NFPA_ref =

}}

}}

Potassium metal can react violently with water producing KOH and hydrogen gas.

:{{chem2|2 K(s) + 2 H2O(l) → 2 KOH(aq) + H2(g)↑}}

File:Potassium water 20.theora.ogv

This reaction is exothermic and releases sufficient heat to ignite the resulting hydrogen in the presence of oxygen. Finely powdered potassium ignites in air at room temperature. The bulk metal ignites in air if heated. Because its density is 0.89{{nbsp}}g/cm³, burning potassium floats in water that exposes it to atmospheric oxygen. Many common fire extinguishing agents, including water, either are ineffective or make a potassium fire worse. Nitrogen, argon, sodium chloride (table salt), sodium carbonate (soda ash), and silicon dioxide (sand) are effective if they are dry. Some Class D dry powder extinguishers designed for metal fires are also effective. These agents deprive the fire of oxygen and cool the potassium metal.{{cite book| url = https://books.google.com/books?id=2fHsoobsCNwC&pg=PA459 |page = 459| title = Fire and Life Safety Inspection Manual| isbn = 978-0-87765-472-8|publisher=Jones & Bartlett Learning| last = Solomon |first=Robert E.| date = 2002}}

During storage, potassium forms peroxides and superoxides. These peroxides may react violently with organic compounds such as oils. Both peroxides and superoxides may react explosively with metallic potassium.{{cite web|url=http://www.hss.doe.gov/nuclearsafety/ns/techstds/standard/hdbk1081/hbk1081d.html |title=DOE Handbook-Alkali Metals Sodium, Potassium, NaK, and Lithium |publisher=Hss.doe.gov |access-date=2010-10-16 |archive-url=https://web.archive.org/web/20100928002539/http://www.hss.doe.gov/nuclearsafety/ns/techstds/standard/hdbk1081/hbk1081d.html |archive-date=2010-09-28}}

Because potassium reacts with water vapor in the air, it is usually stored under anhydrous mineral oil or kerosene. Unlike lithium and sodium, potassium should not be stored under oil for longer than six months, unless in an inert (oxygen-free) atmosphere, or under vacuum. After prolonged storage in air dangerous shock-sensitive peroxides can form on the metal and under the lid of the container, and can detonate upon opening.{{cite web |url=https://www.ncsu.edu/ehs/www99/right/handsMan/lab/Peroxide.pdf |title=Danger: peroxidazable chemicals |last=Wray |first=Thomas K. |publisher=Environmental Health & Public Safety, North Carolina State University |url-status=bot: unknown |archive-url=https://web.archive.org/web/20160729111002/https://www.ncsu.edu/ehs/www99/right/handsMan/lab/Peroxide.pdf |archive-date=2016-07-29 }}

Ingestion of large amounts of potassium compounds, certain drugs, and homeostatic failure, can lead to hyperkalemia, leading to a variety of brady- and tachy-arrhythmias that can be fatal.{{cite book|publisher=Lippincott Williams & Wilkins|chapter-url = https://books.google.com/books?id=BfdighlyGiwC&pg=PA903| chapter = Potassium Chloride and Potassium Permanganate|pages = 903–5|title = Medical toxicology|isbn = 978-0-7817-2845-4|last = Schonwald|first = Seth|date = 2004}}{{cite book|url =https://books.google.com/books?id=l8RkPU1-M5wC&pg=PA223 |publisher=Elsevier Health Sciences|page =223|title =Emergency medicine secrets|isbn =978-1-56053-503-4|last1 =Markovchick |first1=Vincent J.|last2 =Pons |first2=Peter T.|date =2003}}{{Cite journal |last=Clase |first=Catherine M. |last2=Carrero |first2=Juan-Jesus |last3=Ellison |first3=David H. |last4=Grams |first4=Morgan E. |last5=Hemmelgarn |first5=Brenda R. |last6=Jardine |first6=Meg J. |last7=Kovesdy |first7=Csaba P. |last8=Kline |first8=Gregory A. |last9=Lindner |first9=Gregor |last10=Obrador |first10=Gregorio T. |last11=Palmer |first11=Biff F. |last12=Cheung |first12=Michael |last13=Wheeler |first13=David C. |last14=Winkelmayer |first14=Wolfgang C. |last15=Pecoits-Filho |first15=Roberto |date=January 2020 |title=Potassium homeostasis and management of dyskalemia in kidney diseases: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference |url=https://linkinghub.elsevier.com/retrieve/pii/S0085253819310129 |journal=Kidney International |language=en |volume=97 |issue=1 |pages=42–61 |doi=10.1016/j.kint.2019.09.018}} Potassium chloride is used in the U.S. for lethal injection executions.

{{Portal bar|Contents|Science|Medicine|Chemistry|Physics|Geophysics}}

{{reflist}}

• {{cite book|doi = 10.1002/14356007.a22_031.pub2|title = Ullmann's Encyclopedia of Industrial Chemistry|date = 2006|ref=Burkhardt|last = Burkhardt |first=Elizabeth R.|chapter = Potassium and Potassium Alloys|isbn = 978-3-527-30673-2|volume=A22|pages=31–38 }}
• {{cite book|ref=Greenwood|last1=Greenwood|first1=Norman N.|last2=Earnshaw |first2=Alan|date=1997|title=Chemistry of the Elements |edition=2nd|publisher= Butterworth-Heinemann|isbn=978-0-08-037941-8}}
• {{cite book|ref=Holleman|publisher = Walter de Gruyter|date = 2007|edition = 91–100|isbn = 978-3-11-017770-1|chapter-url=https://books.google.com/books?id=mahxPfBdcxcC|title = Lehrbuch der Anorganischen Chemie|first1 = Arnold F.|last1 = Holleman|last2 = Wiberg|first2 = Egon|last3 = Wiberg|first3 = Nils|chapter = Potassium| language = de}}
• {{cite book|doi = 10.1002/14356007.a22_031.pub2|title = Ullmann's Encyclopedia of Industrial Chemistry|date = 2006|ref=Schultz|last1= Schultz|first1 = H.|last2 = Bauer|first2 = G.|last3 = Schachl|first3 = E.|last4 = Hagedorn|first4 = F.|last5 = Schmittinger|first5 = P.|chapter = Potassium compounds|isbn = 978-3-527-30673-2|volume = A22|pages = 39–103}}
• [https://fdc.nal.usda.gov/fdc-app.html#/ National Nutrient Database] {{Webarchive|url=https://web.archive.org/web/20140810230234/http://ndb.nal.usda.gov/ndb/search/list |date=2014-08-10 }} at USDA Website

{{Sister project links|auto=1|wikt=potassium|n=y|s=y|v=Potassium atom|b=Wikijunior:The Elements/Potassium}}

• {{pubchem|Potassium}}

{{Periodic table (navbox)}}

{{Potassium compounds}}

{{Authority control}}

Category:Chemical elements

Category:Alkali metals

Category:Desiccants

Category:Dietary minerals

Category:Reducing agents

Category:Chemical elements with body-centered cubic structure

Category:Articles containing video clips

Category:Pyrophoric materials