Editing Potassium (section)

==Precautions==
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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|thumb|left|alt=A piece of potassium metal is dropped into a clear container of water and skates around, burning with a bright pinkish or lilac flame for a short time until finishing with a pop and splash.|A reaction of potassium metal with water. Hydrogen is produced, and with potassium vapor, burns with a pink or lilac flame. Strongly alkaline potassium hydroxide is formed in solution.]]

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/cm<sup>3</sup>, 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 [[Fire extinguisher|Class D]] dry powder extinguishers designed for metal fires are also effective. These agents deprive the fire of oxygen and cool the potassium metal.<ref>{{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}}</ref>

During storage, potassium forms peroxides and superoxides. These peroxides may react violently with [[organic compound]]s such as oils. Both peroxides and superoxides may react explosively with metallic potassium.<ref>{{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 <!--Added by H3llBot--> |archive-date=2010-09-28}}</ref>

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.<ref>{{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 }}</ref>

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.<ref name="hyper">{{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}}</ref><ref>{{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}}</ref><ref>{{Cite journal |last1=Clase |first1=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|pmid=31706619 }}</ref> Potassium chloride is used in the U.S. for [[lethal injection]] executions.<ref name="hyper" />