Potassium chloride#Biological and medical properties

{{About|the salt|the use of potassium chloride as a medication|Potassium chloride (medical use)|the use of potassium in biology|Potassium in biology}}

{{chembox

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 477162807

| ImageFile = Potassium chloride.jpg

| ImageFile1 = Potassium-chloride-3D-ionic.png

| OtherNames = {{Unbulleted list|Sylvite|Muriate of potash}}

|Section1={{Chembox Identifiers

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 660YQ98I10

| ChEMBL_Ref = {{ebicite|changed|EBI}}

| ChEMBL = 1200731

| KEGG_Ref = {{keggcite|correct|kegg}}

| KEGG = D02060

| InChI = 1/ClH.K/h1H;/q;+1/p-1

| InChIKey = WCUXLLCKKVVCTQ-REWHXWOFAZ

| DrugBank_Ref = {{drugbankcite|correct|drugbank}}

| DrugBank = DB00761

| ChEBI_Ref = {{ebicite|correct|EBI}}

| ChEBI = 32588

| SMILES = [Cl-].[K+]

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/ClH.K/h1H;/q;+1/p-1

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = WCUXLLCKKVVCTQ-UHFFFAOYSA-M

| CASNo = 7447-40-7

| CASNo_Ref = {{cascite|correct|CAS}}

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 4707

| PubChem = 4873

| RTECS = TS8050000

}}

|Section2={{Chembox Properties

| Formula = KCl

| MolarMass = 74.555 g·mol⁻¹

| Appearance = white crystalline solid

| Odor = odorless

| Density = 1.984 g/cm³

| Solubility = 27.77 g/100mL (0 °C)
33.97 g/100mL (20 °C)
54.02 g/100mL (100 °C)

| SolubleOther = Soluble in glycerol, alkalies
Slightly soluble in alcohol Insoluble in ether{{cite web | url = http://www.inchem.org/documents/pims/pharm/potasscl.htm | title = Potassium chloride (PIM 430) | at = 3.3.1 Properties of the substance | publisher = International Programme on Chemical Safety | access-date = 2011-01-17 | archive-date = 2010-12-04 | archive-url = https://web.archive.org/web/20101204104016/http://www.inchem.org/documents/pims/pharm/potasscl.htm | url-status = live }}

| Solvent1 = ethanol

| Solubility1 = 0.288 g/L (25 °C){{cite web |title=periodic-table-of-elements.org |url=https://periodic-table-of-elements.org/SOLUBILITY/potassium_chloride |access-date=4 October 2019 |format=website shows values in g/100ml |archive-date=29 October 2020 |archive-url=https://web.archive.org/web/20201029075558/https://periodic-table-of-elements.org/SOLUBILITY/potassium_chloride |url-status=dead }}

| MeltingPtC = 770

| MeltingPt_notes =

| BoilingPtC = 1420

| RefractIndex = 1.4902 (589 nm)

| pKa = ~7

| MagSus = −39.0·10⁻⁶ cm³/mol

}}

|Section3={{Chembox Structure

| CrystalStruct = face centered cubic

| SpaceGroup = Fm{{overline|3}}m, No. 225

| LattConst_a = 629.2 pm{{cite book | vauthors = Sirdeshmukh DB, Sirdeshmukh L, Subhadra KG |title=Alkali Halides: A Handbook of Physical Properties |date=2001 |publisher=Springer |location=Berlin |isbn=978-3-540-42180-1}}

| Coordination = Octahedral (K⁺)
Octahedral (Cl⁻)

}}

|Section5={{Chembox Thermochemistry

| DeltaHf = −436 kJ·mol⁻¹{{cite book| vauthors = Zumdahl SS |title =Chemical Principles 6th Ed.| publisher = Houghton Mifflin Company| year = 2009| isbn = 978-0-618-94690-7|page=A22}}

| Entropy = 83 J·mol⁻¹·K⁻¹

}}

|Section6={{Chembox Pharmacology

| ATCCode_prefix = A12

| ATCCode_suffix = BA01

| ATC_Supplemental = {{ATC|B05|XA01}}

| AdminRoutes = Oral, IV, IM

| Bioavail =

| Excretion = Kidney: 90%; Fecal: 10%{{cite web | url = https://pubchem.ncbi.nlm.nih.gov/compound/4873 | title = Compound Summary for Potassium Chloride | id = CID 4873 | work = PubChem | publisher = U.S. National Library of Medicine | access-date = 17 October 2015 | archive-date = 2 August 2023 | archive-url = https://web.archive.org/web/20230802100708/https://pubchem.ncbi.nlm.nih.gov/compound/4873 | url-status = live }}

| HalfLife =

| Metabolism =

| ProteinBound =

| Dependence_liability =

}}

|Section7={{Chembox Hazards

| ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics1450.htm ICSC 1450]

| FlashPt = Non-flammable

| NFPA-H = 1

| NFPA-F = 0

| NFPA-R = 0

| NFPA-S =

| LD50 = 2600 mg/kg (oral, rat){{cite web|url=https://chem.nlm.nih.gov/chemidplus/rn/7447-40-7 | archive-url = https://web.archive.org/web/20150715234607/https://chem.nlm.nih.gov/chemidplus/rn/7447-40-7 | archive-date = 15 July 2015 | work = ChemIDplus | title = 7447-40-7 - WCUXLLCKKVVCTQ-UHFFFAOYSA-M - Potassium chloride [USP:JAN] | vauthors = Chambers M | publisher = U.S. National Library of Medicine |access-date=22 December 2017}}

}}

|Section8={{Chembox Related

| OtherAnions = Potassium fluoride
Potassium bromide
Potassium iodide

| OtherCations = Lithium chloride
Sodium chloride
Rubidium chloride
Caesium chloride
Ammonium chloride

| OtherCompounds = Potassium hypochlorite
Potassium chlorite
Potassium chlorate
Potassium perchlorate

}}

Potassium chloride (KCl, or potassium salt) is a metal halide salt composed of potassium and chlorine. It is odorless and has a white or colorless vitreous crystal appearance. The solid dissolves readily in water, and its solutions have a salt-like taste. Potassium chloride can be obtained from ancient dried lake deposits.{{Cite book| vauthors = Rayner-Canham G, Overton T |title=Descriptive inorganic chemistry|date=22 December 2013|isbn=978-1-4641-2557-7|edition=Sixth|location=New York, NY|oclc=882867766|publisher=W. H. Freeman}} KCl is used as a salt substitute for table salt (NaCl), a fertilizer,{{Cite web|url=http://extension.psu.edu/agronomy-guide/cm/sec2/sec28c|title=Potassium Fertilizers (Penn State Agronomy Guide)|website=Penn State Agronomy Guide (Penn State Extension)|access-date=2016-12-10|archive-url=https://web.archive.org/web/20161220172926/http://extension.psu.edu/agronomy-guide/cm/sec2/sec28c|archive-date=2016-12-20|url-status=dead}} as a medication, in scientific applications, in domestic water softeners (as a substitute for sodium chloride salt), as a feedstock, and in food processing, where it may be known as E number additive E508.

It occurs naturally as the mineral sylvite, which is named after salt's historical designations sal degistivum Sylvii and sal febrifugum Sylvii,{{Cite book |last=Watts |first=Henry |url=https://books.google.com/books?id=d-bkUHqUZ5AC&pg=PA147 |title=A Dictionary of Chemistry and the Allied Branches of Other Sciences |date=1883 |publisher=Longmans, Green, and Company |language=en}} and in combination with sodium chloride as sylvinite.

Uses

=Fertilizer=

File:Compacted potassium chloride, fertilizer grade.jpgThe majority of the potassium chloride produced is used for making fertilizer, called potash, since the growth of many plants is limited by potassium availability.{{cite book|isbn=978-93-5606-271-9|title=The Nature and Properties of Soils|first1=Ray|last1=Weil|first2=Nyle|last2=Brady|year=2022|publisher=Pearson Education}}{{cite journal|doi=10.1051/agro/2009023 |title=Mineral sources of potassium for plant nutrition. A review |date=2010 |last1=Manning |first1=David A.C. |journal=Agronomy for Sustainable Development |volume=30 |issue=2 |pages=281–294 |bibcode=2010AgSD...30..281M }} The term "potash" refers to various mined and manufactured salts that contain potassium in water-soluble form. Potassium chloride sold as fertilizer is known as "muriate of potash"—it is the common name for potassium chloride ({{chem|K|Cl}}) used in agriculture.{{cite book|isbn=978-93-325-7034-4 |title=Soil Fertility and Fertilizers: An Introduction to Nutrient Management |last1=Havlin |first1=John L. |last2=Tisdale |first2=Samuel L. |last3=Nelson |first3=Werner L. |last4=Beaton |first4=James D. |date=2016 |publisher=Pearson }}{{cite book|url=http://potassium.ipni.net/ipniweb/region/potassium.nsf/0/58AFA539CC03133085258178006F5140/$FILE/NSS-03%20PotassiumChloride.pdf|title=Nutrient Source Specifics: Potassium Chloride. Ref. No. 17 #13075|publisher=International Plant Nutrition Institute (IPNI)|access-date=2024-11-24|archive-date=2024-04-14|archive-url=https://web.archive.org/web/20240414005645/http://potassium.ipni.net/ipniweb/region/potassium.nsf/0/58AFA539CC03133085258178006F5140/%24FILE/NSS-03%20PotassiumChloride.pdf|url-status=live}}{{cite book |last1=Havlin |first1=John L. |last2=Tisdale |first2=Samuel L. |last3=Nelson |first3=Werner L. |last4=Beaton |first4=James D. |title=Soil Fertility and Fertilizers |edition=8th |publisher=Pearson Education |year=2014 |isbn=978-0-13-503373-9 |pages=186–188 |chapter=Potassium |url=https://www.pearson.com/us/higher-education/program/Havlin-Soil-Fertility-and-Fertilizers-8th-Edition/PGM334285.html}}{{cite journal |last1=Manning |first1=David A. C. |title=Mineral sources of potassium for plant nutrition. A review |journal=Agronomy for Sustainable Development |volume=30 |issue=2 |year=2010 |pages=281–294 |doi=10.1051/agro/2009023 |bibcode=2010AgSD...30..281M |url=https://link.springer.com/article/10.1051/agro/2009023 |access-date=2024-11-24 |archive-date=2024-02-28 |archive-url=https://web.archive.org/web/20240228002627/https://link.springer.com/article/10.1051/agro/2009023 |url-status=live |url-access= }} The vast majority of potash fertilizer worldwide is sold as muriate of potash.{{cite book|url=https://pubs.usgs.gov/periodicals/mcs2024/mcs2024-potash.pdf|series=United States Geological Survey (USGS)|title=Mineral Commodity Summaries: Potash|publisher=U.S. Department of the Interior.|access-date=2024-11-24|archive-date=2024-11-12|archive-url=https://web.archive.org/web/20241112131501/https://pubs.usgs.gov/periodicals/mcs2024/mcs2024-potash.pdf|url-status=live}}{{cite book|url=https://openknowledge.fao.org/server/api/core/bitstreams/b66da618-027b-4124-a5c7-f870cd671484/content|title=FAO Fertilizer and Plant Nutrition Bulletin.|chapter=Fertilizer Use by Crop|publisher=Food and Agriculture Organization of the United Nations|access-date=2024-11-24|archive-date=2024-09-02|archive-url=https://web.archive.org/web/20240902213631/https://openknowledge.fao.org/server/api/core/bitstreams/b66da618-027b-4124-a5c7-f870cd671484/content|url-status=live}} The dominance of muriate of potash in the fertilizer market is due to its high potassium content (approximately 60% {{chem|K|2|O}} equivalent) and relative affordability compared to other potassium sources like sulfate of potash (potassium sulfate).{{cite book |last1=Roy |first1=Ram N. |last2=Finck |first2=Arnold |last3=Blair |first3=Graeme J. |last4=Tandon |first4=H.L.S. |title=Plant Nutrition for Food Security: A Guide for Integrated Nutrient Management |series=FAO Fertilizer and Plant Nutrition Bulletin 16 |publisher=Food and Agriculture Organization of the United Nations |year=2006 |isbn=92-5-105490-8|pages=141–142 |url=http://www.fao.org/3/a0443e/a0443e00.htm |access-date=2024-11-24 |archive-date=2023-01-02 |archive-url=https://web.archive.org/web/20230102211021/https://www.fao.org/3/a0443e/a0443e00.htm |url-status=live }} Potassium is one of the three primary macronutrients essential for plant growth, alongside nitrogen and phosphorus. Potassium plays a vital role in various plant physiological processes, including enzyme activation, photosynthesis, protein synthesis, and water regulation.{{cite book |last1=Brady |first1=Nyle C. |last2=Weil |first2=Ray R. |title=The Nature and Properties of Soils |edition=15th |publisher=Pearson Education |year=2016 |isbn=978-0-13-325448-8 |pages=594–595 |chapter=Plant Nutrients and Nutrient Uptake |url=https://www.pearson.com/us/higher-education/program/Brady-Nature-and-Properties-of-Soils-The-15th-Edition/PGM203380.html}}{{cite journal |last1=Römheld |first1=Volker |last2=Kirkby |first2=Ernest A. |title=Research on potassium in agriculture: needs and prospects |journal=Plant and Soil |volume=335 |issue=1 |year=2010 |pages=155–180 |doi=10.1007/s11104-010-0520-1 |bibcode=2010PlSoi.335..155R |url=https://link.springer.com/article/10.1007/s11104-010-0520-1 |access-date=2024-11-24 |archive-date=2024-07-09 |archive-url=https://web.archive.org/web/20240709175824/https://link.springer.com/article/10.1007/s11104-010-0520-1 |url-status=live |url-access=subscription }} For watering plants, a moderate concentration of potassium chloride (KCl) is used to avoid potential toxicity: 6 mM (millimolar) is generally effective and safe for most plants, that is approximately {{convert|0.4|g}} per liter of water.{{cite journal|doi=10.3389/fpls.2020.00904|doi-access=free |title=Effects of Potassium Levels on Plant Growth, Accumulation and Distribution of Carbon, and Nitrate Metabolism in Apple Dwarf Rootstock Seedlings |date=2020 |last1=Xu |first1=Xinxiang |last2=Du |first2=Xin |last3=Wang |first3=Fen |last4=Sha |first4=Jianchuan |last5=Chen |first5=Qian |last6=Tian |first6=Ge |last7=Zhu |first7=Zhanling |last8=Ge |first8=Shunfeng |last9=Jiang |first9=Yuanmao |journal=Frontiers in Plant Science |volume=11 |page=904 |pmid=32655607 |pmc=7325393 }}{{cite journal|doi=10.1371/journal.pone.0066259|doi-access=free |title=Optimisation of Potassium Chloride Nutrition for Proper Growth, Physiological Development and Bioactive Component Production in Prunella vulgaris L |date=2013 |last1=Chen |first1=Yuhang |last2=Yu |first2=Manman |last3=Zhu |first3=Zaibiao |last4=Zhang |first4=Lixia |last5=Guo |first5=Qiaosheng |journal=PLOS ONE |volume=8 |issue=7 |pages=e66259 |pmid=23874390 |pmc=3706589 |bibcode=2013PLoSO...866259C }}

=Medical use=

Potassium is vital in the human body, and potassium chloride by mouth is the standard means to treat low blood potassium, although it can also be given intravenously. It is on the World Health Organization's List of Essential Medicines.{{cite book | vauthors = ((World Health Organization)) | title = World Health Organization model list of essential medicines: 21st list 2019 | year = 2019 | hdl = 10665/325771 | author-link = World Health Organization | publisher = World Health Organization | location = Geneva | id = WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO | hdl-access=free }} It is also an ingredient in Oral Rehydration Therapy (ORT)/solution (ORS) to reduce hypokalemia caused by diarrhoea,{{cite book |last1=World Health Organization |url=https://apps.who.int/iris/bitstream/handle/10665/69227/WHO_FCH_CAH_06.1.pdf |title=Oral rehydration salts: production of the new ORS |last2=Unicef |publisher= |year=2006 |series=WHO/FCH/CAH/06.1 |hdl=10665/69227 |id= |author-link=World Health Organization |author-link2=UNICEF |access-date=2024-11-14 |archive-date=2023-06-03 |archive-url=https://web.archive.org/web/20230603021940/https://apps.who.int/iris/bitstream/handle/10665/69227/WHO_FCH_CAH_06.1.pdf |url-status=live }} which is also on the WHO's List of Essential Medicines.

Potassium chloride contains 52% of elemental potassium by mass.{{cite journal|doi=10.1088/1755-1315/648/1/012185 |title=Applications of guano and K₂CO₃ on soil potential-P, potential-K on Andisols |date=2021 |last1=Zakiah |first1=K. |last2=Maulana |first2=M. R. |last3=Widowati |first3=L. R. |last4=Mutakin |first4=J. |journal=IOP Conference Series: Earth and Environmental Science |volume=648 |issue=1 |page=012185 |bibcode=2021E&ES..648a2185Z |doi-access=free }}

Overdose causes hyperkalemia which can disrupt cell signaling to the extent that the heart will stop, reversibly in the case of some open heart surgeries.{{cite journal |vauthors=Hoppe LK, Muhlack DC, Koenig W, Carr PR, Brenner H, Schöttker B |title=Association of Abnormal Serum Potassium Levels with Arrhythmias and Cardiovascular Mortality: a Systematic Review and Meta-Analysis of Observational Studies |journal=Cardiovasc Drugs Ther |volume=32 |issue=2 |pages=197–212 |date=20 April 2018 |pmid=29679302 |doi=10.1007/s10557-018-6783-0}}{{cite journal |vauthors=Simon G |title=Detection of Fatal Potassium Overdose: A Case Report and Review of the Literature |journal=Diagnostics |volume=13 |issue=7 |date=4 April 2023 |page=1339 |pmid=37046560 |pmc=10093193 |doi=10.3390/diagnostics13071339|doi-access=free }}{{cite journal |vauthors=Fan Y, Wu M, Li X, Zhao J, Shi J, Ding L, Jiang H, Li Z, Zhang W, Ma T, Wang D, Ma L |title=Potassium levels and the risk of all-cause and cardiovascular mortality among patients with cardiovascular diseases: a meta-analysis of cohort studies |journal=Nutr J |volume=23 |issue=1 |pages=8 |date=10 January 2024 |pmid=38195532 |pmc=10777575 |doi=10.1186/s12937-023-00888-z|doi-access=free }}

=Culinary use=

Potassium chloride can be used as a salt substitute for food, but because not everyone likes its flavor, it is often mixed with ordinary table salt (sodium chloride) to improve the taste, to form low sodium salt. The addition of 1 ppm of thaumatin considerably reduces this bitterness.{{cite book | vauthors = Lorient D, Linden G |title=New ingredients in food processing: biochemistry and agriculture |publisher=CRC Press |location=Boca Raton |year=1999 |page= 357 |isbn=978-1-85573-443-2 |quote=... in dietary food containing potassium chloride, thaumatin added in the ratio of 1 ppm considerably reduces the sensation of bitterness. ... }} Complaints of bitterness or a chemical or metallic taste are also reported with potassium chloride used in food.{{cite journal | vauthors = Sinopoli DA, Lawless HT | title = Taste properties of potassium chloride alone and in mixtures with sodium chloride using a check-all-that-apply method | journal = Journal of Food Science | volume = 77 | issue = 9 | pages = S319–S322 | date = September 2012 | pmid = 22901084 | doi = 10.1111/j.1750-3841.2012.02862.x }}

The World Health Organization guideline Use of lower-sodium salt substitutes strongly recommends reducing sodium intake to less than 2 g/day and conditionally recommends replacing regular table salt with lower-sodium salt substitutes that contain potassium. This recommendation is intended for adults (not pregnant women or children) in general populations, excluding individuals with kidney impairments or with other circumstances or conditions that might compromise potassium excretion.{{Cite web |title=Overview of the WHO guideline on lower-sodium salt substitutes |url=https://cdn.who.int/media/docs/default-source/nutrition-and-food-safety/events/2025/launch-of-lsss-guideline-presentation-1-overview.pdf |first=Rain |last=Yamamoto |date=27 January 2025 |access-date=31 January 2025 |publisher=World Health Organization }}{{Cite web |title=Use of lower-sodium salt substitutes: WHO guideline |url=https://www.who.int/publications/i/item/9789240105591 |date=27 January 2025 |access-date=31 January 2025 |publisher=World Health Organization }}{{Cite web |title=Use of lower-sodium salt substitutes: WHO guideline |url=https://iris.who.int/bitstream/handle/10665/380227/9789240105591-eng.pdf?sequence=1 |date=27 January 2025 |access-date=31 January 2025 |publisher=World Health Organization }}

=Execution=

In the United States, potassium chloride is used as the final drug in the three-injection sequence of lethal injection as a form of capital punishment. It induces cardiac arrest, ultimately killing the person.{{Cite web |title=Overview of Lethal Injection Protocols |url=https://deathpenaltyinfo.org/executions/lethal-injection/overview-of-lethal-injection-protocols |access-date=2024-02-28 |website=Death Penalty Information Center |language=en-US |archive-date=2024-08-06 |archive-url=https://web.archive.org/web/20240806224149/https://deathpenaltyinfo.org/executions/lethal-injection/overview-of-lethal-injection-protocols |url-status=live }}

=Industrial=

As a chemical feedstock, the salt is used for the manufacture of potassium hydroxide and potassium metal. It is also used in medicine, lethal injections, scientific applications, food processing, soaps, and as a sodium-free substitute for table salt for people concerned about the health effects of sodium.{{citation needed|date=November 2024}}

It is used as a supplement in animal feed to boost the potassium level in the feed. As an added benefit, it is known to increase milk production.{{citation needed|date=November 2024}}

It is sometimes used in solution as a completion fluid in petroleum and natural gas operations, as well as being an alternative to sodium chloride in household water softener units.{{citation needed|date=November 2024}}

Glass manufacturers use granular potash as a flux, lowering the temperature at which a mixture melts. Because potash imparts excellent clarity to glass, it is commonly used in eyeglasses, glassware, televisions, and computer monitors.{{citation needed|date=November 2024}}

Because natural potassium contains a tiny amount of the isotope potassium-40, potassium chloride is used as a beta radiation source to calibrate radiation monitoring equipment. It also emits a relatively low level of 511 keV gamma rays from positron annihilation, which can be used to calibrate medical scanners.{{citation needed|date=November 2024}}

Potassium chloride is used in some de-icing products designed to be safer for pets and plants, though these are inferior in melting quality to calcium chloride. It is also used in various brands of bottled water.{{citation needed|date=November 2024}}

Potassium chloride was once used as a fire extinguishing agent, and in portable and wheeled fire extinguishers. Known as Super-K dry chemical, it was more effective than sodium bicarbonate-based dry chemicals and was compatible with protein foam. This agent fell out of favor with the introduction of potassium bicarbonate (Purple-K) dry chemical in the late 1960s, which was much less corrosive, as well as more effective. It is rated for B and C fires.{{citation needed|date=November 2024}}

Along with sodium chloride and lithium chloride, potassium chloride is used as a flux for the gas welding of aluminium.{{citation needed|date=November 2024}}

Potassium chloride is also an optical crystal with a wide transmission range from 210 nm to 20 μm. While cheap, KCl crystals are hygroscopic. This limits its application to protected environments or short-term uses such as prototyping. Exposed to free air, KCl optics will "rot". Whereas KCl components were formerly used for infrared optics, they have been entirely replaced by much tougher crystals such as zinc selenide.{{citation needed|date=November 2024}}

Potassium chloride is used as a scotophor with designation P10 in dark-trace CRTs, e.g. in the Skiatron.{{citation needed|date=November 2024}}

Toxicity

The typical amounts of potassium chloride found in the diet appear to be generally safe.{{cite web | author = Center for Food Safety and Applied Nutrition|title=GRAS Substances (SCOGS) Database - Select Committee on GRAS Substances (SCOGS) Opinion: Potassium chloride|url=https://www.fda.gov/Food/IngredientsPackagingLabeling/GRAS/SCOGS/ucm261000.htm|archive-url=https://wayback.archive-it.org/7993/20171031064321/https://www.fda.gov/Food/IngredientsPackagingLabeling/GRAS/SCOGS/ucm261000.htm|url-status=dead|archive-date=31 October 2017|website=www.fda.gov|access-date=21 July 2019|language=en}} In larger quantities, however, potassium chloride is toxic. The {{LD50}} of orally ingested potassium chloride is approximately 2.5 g/kg, or {{convert|190|g|oz}} for a body mass of {{convert|75|kg|lb}}. In comparison, the {{LD50}} of sodium chloride (table salt) is 3.75 g/kg.

Intravenously, the {{LD50}} of potassium chloride is far smaller, at about 57.2 mg/kg to 66.7 mg/kg; this is found by dividing the lethal concentration of positive potassium ions (about 30 to 35 mg/kg){{cite journal | vauthors = Bhatkhande CY, Joglekar VD | title = Fatal poisoning by potassium in human and rabbit | journal = Forensic Science | volume = 9 | issue = 1 | pages = 33–36 | date = 1977-01-01 | pmid = 838413 | doi = 10.1016/0300-9432(77)90062-0 }} by the proportion by mass of potassium ions in potassium chloride (about 0.52445 mg K⁺/mg KCl).{{Cite web|url=https://www.convertunits.com/molarmass/KCl|title=Molecular weight of KCl|website=www.convertunits.com|access-date=2018-11-04|archive-date=2018-11-05|archive-url=https://web.archive.org/web/20181105012256/https://www.convertunits.com/molarmass/KCl|url-status=live}}

Chemical properties

=Solubility=

KCl is soluble in a variety of polar solvents.

class="wikitable" style="margin: 1em;" \|+ Solubility{{cite book\| vauthors = Burgess J \|title=Metal Ions in Solution\|publisher=Ellis Horwood\|place=New York\|year=1978\|isbn=978-0-85312-027-8}}{{page needed\|date=July 2015}} ! Solvent !! Solubility (g/kg of solvent at 25 °C)
Water	360
Liquid ammonia	0.4
Liquid sulfur dioxide	0.41
Methanol	5.3
Ethanol	0.37
Formic acid	192
Sulfolane	0.04
Acetonitrile	0.024
Acetone	0.00091
Formamide	62
Acetamide	24.5
Dimethylformamide	0.17–0.5

Solutions of KCl are common standards, for example for calibration of the electrical conductivity of (ionic) solutions, since KCl solutions are stable, allowing for reproducible measurements. In aqueous solution, it is essentially fully ionized into solvated {{chem2|K+}} and {{chem2|Cl-}} ions.

=Redox and the conversion to potassium metal=

Although potassium is more electropositive than sodium, KCl can be reduced to the metal by reaction with metallic sodium at 850 °C because the more volatile potassium can be removed by distillation (see Le Chatelier's principle):

:{{chem2 | KCl_{(l)} + Na_{(l)} <-> NaCl_{(l)} + K_{(g)} }}

This method is the main method for producing metallic potassium. Electrolysis (used for sodium) fails because of the high solubility of potassium in molten KCl.{{cite book | vauthors = Burkhardt ER |chapter=Potassium and Potassium Alloys |year=2006 |title=Ullmann's Encyclopedia of Industrial Chemistry |doi=10.1002/14356007.a22_031.pub2|isbn=978-3-527-30673-2 }}

=Other potassium chloride stoichiometries=

Potassium chlorides with formulas other than KCl have been predicted to become stable under pressures of 20 GPa or more.{{Cite journal|last1=Zhang|first1=Weiwei|last2=Oganov|first2=Artem R.|last3=Zhu|first3=Qiang|last4=Lobanov|first4=Sergey S.|last5=Stavrou|first5=Elissaios|last6=Goncharov|first6=Alexander F.|title=Stability of numerous novel potassium chlorides at high pressure|journal=Sci Rep|volume=6|page=26265|date=23 May 2016|doi=10.1038/srep26265|pmid=27211847 |pmc=4876327|bibcode=2016NatSR...626265Z }} Among these, two phases of KCl₃ were synthesized and characterized. At 20-40 GPa, a trigonal structure containing K⁺ and Cl₃⁻ is obtained; above 40 GPa this gives way to a phase isostructural with the intermetallic compound Cr₃Si.{{citation needed|date=December 2024}}

Physical properties

Under ambient conditions, the crystal structure of potassium chloride is like that of NaCl. It adopts a face-centered cubic structure known as the B1 phase with a lattice constant of roughly 6.3 Å. Crystals cleave easily in three directions. Other polymorphic and hydrated phases are adopted at high pressures.{{cite journal | vauthors = Yamashita K, Komatsu K, Kagi H | title = Crystal structure of potassium chloride monohydrate: water intercalation into the B1 structure of KCl under high pressure | journal = Acta Crystallographica Section C | volume = 78 | issue = Pt 12 | pages = 749–754 | date = December 2022 | pmid = 36468558 | pmc = 9720884 | doi = 10.1107/S2053229622011135 | bibcode = 2022AcCrC..78..749Y }}

Some other properties are

Transmission range: 210 nm to 20 μm
Transmittivity = 92% at 450 nm and rises linearly to 94% at 16 μm
Refractive index = 1.456 at 10 μm
Reflection loss = 6.8% at 10 μm (two surfaces)
dN/dT (expansion coefficient)= −33.2×10⁻⁶/°C
dL/dT (refractive index gradient)= 40×10⁻⁶/°C
Thermal conductivity = 0.036 W/(cm·K)
Damage threshold (Newman and Novak): 4 GW/cm² or 2 J/cm² (0.5 or 1 ns pulse rate); 4.2 J/cm² (1.7 ns pulse rate Kovalev and Faizullov)

As with other compounds containing potassium, KCl in powdered form gives a lilac flame.

Production

File:Sylvin (aka).jpg

File:Sylvinite.jpg

Potassium chloride is extracted from minerals sylvite, carnallite, and potash. It is also extracted from salt water and can be manufactured by crystallization from solution, flotation or electrostatic separation from suitable minerals. It is a by-product of the production of nitric acid from potassium nitrate and hydrochloric acid.

Most potassium chloride is produced as agricultural and industrial-grade potash in Saskatchewan, Canada, Russia, and Belarus. Saskatchewan alone accounted for over 25% of the world's potash production in 2017.{{Cite web | publisher = U.S. Geological Survey | title = Mineral Commodity Summaries | date = January 2018 |url=https://minerals.usgs.gov/minerals/pubs/commodity/potash/mcs-2018-potas.pdf | archive-url = https://web.archive.org/web/20190110210319/https://minerals.usgs.gov/minerals/pubs/commodity/potash/mcs-2018-potas.pdf | archive-date = 10 January 2019 }}

=Laboratory methods=

Potassium chloride is inexpensively available and is rarely prepared intentionally in the laboratory. It can be generated by treating potassium hydroxide (or other potassium bases) with hydrochloric acid:

:{{chem2 | KOH + HCl -> KCl + H2O }}

This conversion is an acid-base neutralization reaction. The resulting salt can then be purified by recrystallization. Another method would be to allow potassium to burn in the presence of chlorine gas, also a very exothermic reaction:

:{{chem2 | 2 K + Cl2 -> 2 KCl }}