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Revision as of 13:57, 5 December 2011 editBeetstra (talk | contribs)Edit filter managers, Administrators172,031 edits Saving copy of the {{chembox}} taken from revid 457776740 of page Potassium_nitrite for the Chem/Drugbox validation project (updated: '').		Latest revision as of 12:30, 4 October 2024 edit Peter Smyth (talk | contribs)97 editsm →Discovery: Correct link to town of Köping
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	{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}}
	{{chembox		{{chembox
			| Watchedfields = changed
	| verifiedrevid = 443117735
			| verifiedrevid = 464212156
	| Reference =		| Reference =
	| Name = Potassium nitrite		| Name = Potassium nitrite
			| ImageFile = Potassium nitrite ball-and-stick.png
	| ImageFile1 =
			| ImageFile2 = Potassium_nitrite_KNO2.jpg
	| ImageSize1 =
			| ImageSize =
	| IUPACName =		| IUPACName =
	| OtherNames =		| OtherNames =
	| Section1 = {{Chembox Identifiers		|Section1={{Chembox Identifiers
			| CASNo = 7758-09-0
	| UNII_Ref = {{fdacite|correct|FDA}}
			| CASNo_Ref = {{cascite|correct|CAS}}
			| ChEMBL = 3186418
			| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
			| ChemSpiderID = 22857
			| EINECS = 231-832-4
			| PubChem = 516910
			| UNNumber = 1488
			| RTECS = TT3750000
			| UNII_Ref = {{fdacite|correct|FDA}}
	| UNII = 794654G42L		| UNII = 794654G42L
	| InChI = 1/K.HNO2/c;2-1-3/h;(H,2,3)/q+1;/p-1		| InChI = 1/K.HNO2/c;2-1-3/h;(H,2,3)/q+1;/p-1
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	| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}		| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
	| StdInChIKey = BXNHTSHTPBPRFX-UHFFFAOYSA-M		| StdInChIKey = BXNHTSHTPBPRFX-UHFFFAOYSA-M
	| CASNo = 7758-09-0
	| CASNo_Ref = {{cascite|correct|CAS}}
	| PubChem = 516910
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 22857
	| UNNumber =
	| RTECS = TT3750000
	}}		}}
	| Section2 = {{Chembox Properties		|Section2={{Chembox Properties
	| Formula = KNO<sub>2</sub>		| Formula = KNO<sub>2</sub>
	| MolarMass = 85.10379 g/mol		| MolarMass = 85.10379 g/mol
	| Appearance = white or slight yellow solid <br /> ]		| Appearance = white or slight yellow solid <br /> ]
	| Solubility = 281 g/100 mL (0 °C) <br /> 413 g/100 mL (100 °C)		| Solubility = 281 g/100 mL (0 °C) <br> 312 g/100 mL (25 °C) <br> 413 g/100 mL (100 °C)
	| SolubleOther = soluble in ], ]		| SolubleOther = soluble in ], ]
	| Density = 1.914986 g/cm<sup>3</sup>		| Density = 1.914986 g/cm<sup>3</sup>
	| MeltingPt = 440.02 °C (decomp)		| MeltingPtC = 440.02
			| MeltingPt_notes = (decomposes)
	| BoilingPt =
			| BoilingPtC = 537
			| BoilingPt_notes = (explodes)
			| MagSus = &minus;23.3·10<sup>−6</sup> cm<sup>3</sup>/mol
	}}		}}
	| Section3 = {{Chembox Structure		|Section3={{Chembox Structure
	| Coordination =		| Coordination =
	| CrystalStruct =		| CrystalStruct =
	}}		}}
	| Section7 = {{Chembox Hazards		|Section4={{Chembox Thermochemistry
			| DeltaHf = -369.8 kJ/mol
	| ExternalMSDS =
			| HeatCapacity = 107.4 J/mol K
	| EUIndex =
			}}
	| EUClass = Oxidant ('''O''')<br/>Harmful ('''Xn''')<br/>Dangerous for the environment ('''N''')
			|Section7={{Chembox Hazards
	| RPhrases = {{R8}} {{R25}} {{R50}}.
			| ExternalSDS =
	| SPhrases = {{S45}} {{S61}}
			| GHSPictograms = {{GHS03}}{{GHS06}}{{GHS09}}
	| MainHazards =
	| NFPA-H = 2		| GHSSignalWord = Danger
			| HPhrases = {{H-phrases|272|301|400}}
	| NFPA-F = 0
			| PPhrases = {{P-phrases|210|220|221|264|270|273|280|301+310|321|330|370+378|391|405|501}}
	| NFPA-R = 2
	| NFPA-O = OX		| MainHazards =
			| NFPA-H = 3
	| FlashPt = Non-flammable
	| LD50 = 235 mg/kg		| NFPA-F = 0
			| NFPA-R = 2
	}}
			| NFPA-S = OX
	| Section8 = {{Chembox Related
			| FlashPt = Non-flammable
	| OtherAnions = ]
			| LD50 = 235 mg/kg
	| OtherCations = ]
	| OtherCpds =
	}}		}}
			|Section8={{Chembox Related
			| OtherAnions = ]
			| OtherCations = ]
			| OtherCompounds =
			}}
	}}		}}
			'''Potassium nitrite''' (distinct from ]) is the ] with the ] {{chem2|auto=1|KNO2}}. It is an ] of ] ions K<sup>+</sup> and ] ions NO<sub>2</sub><sup>−</sup>, which forms a white or slightly yellow, hygroscopic ] powder that is soluble in water.<ref>{{cite web|last=Santa Cruz Biotechnology|title=Potassium Nitrite Materials and Safety Sheet}}</ref>
			It is a strong oxidizer and may accelerate the combustion of other materials. Like other nitrite salts such as ], potassium nitrite is toxic if swallowed, and laboratory tests suggest that it may be ] or ]. Gloves and safety glasses are usually used when handling potassium nitrite.
			==Discovery==
			] is present at trace levels in soil, natural waters, plant and animal tissues, and fertilizer.<ref name="American Heart Association">{{Cite journal |doi = 10.1161/CIRCULATIONAHA.107.753814|pmid = 18427145|title = Therapeutic Uses of Inorganic Nitrite and Nitrate|journal = Circulation|volume = 117|issue = 16|pages = 2151–2159|year = 2008|last1 = Butler|first1 = Anthony R.|last2 = Feelisch|first2 = Martin|doi-access = free}}</ref> The pure form of nitrite was first made by the Swedish chemist ] working in the laboratory of his pharmacy in the market town of ]. He heated ] at red heat for half an hour and obtained what he recognized as a new “salt.” The two compounds (potassium nitrate and nitrite) were characterized by ] and the reaction was established as:
			:<chem>2KNO3 -> 2KNO2 + O2</chem>
			==Production==
			Potassium nitrite can be obtained by the reduction of potassium nitrate. The production of potassium nitrite by absorption of nitrogen oxides in ] or ] is not employed on a large scale because of the high price of these alkalies. Furthermore, the fact that potassium nitrite is highly soluble in water makes the solid difficult to recover.
			==Reactions==
			The mixing of ] and KNO<sub>2</sub> produces changes from white solids to yellow liquid and then to orange solid, forming ] and ammonia gases. No external energy is used and the reactions are carried out with a small amount of O<sub>2</sub>.<ref>{{cite journal|last=Wollin|first=Goesta|author2=William B.F. Ryan|title=Synthesis of protein, nucleosides and other organic compounds from cyanamide and potassium nitrite under possible primitive earth conditions|journal=Biochimica et Biophysica Acta (BBA) - General Subjects|date=May 16, 1979|volume=584|issue=3|pages=493–506|doi=10.1016/0304-4165(79)90122-3|pmid=454677}}</ref>
			Potassium nitrite forms potassium nitrate when heated in the presence of oxygen from 550 °C to 790 °C. The rate of reaction increases with temperature, but the extent of reaction decreases. At 550 °C and 600 °C the reaction is continuous and eventually goes to completion. From 650 °C to 750 °C, as the case of decomposition of potassium nitrate is, the system attains ]. At 790 °C, a rapid decrease in volume is first observed, followed by a period of 15 minutes during which no volume changes occur. This is then followed by an increase in volume due primarily to the evolution of nitrogen, which is attributed to the ] of potassium nitrite.<ref name=Freeman>{{cite journal|last=Freeman|first=Eli|title=The Kinetics of the Thermal Decomposition of Potassium Nitrate and of the Reaction between Potassium Nitrite and Oxygen|journal=Journal of the American Chemical Society|date=Feb 20, 1957|volume=79|issue=4|pages=838–842|doi=10.1021/ja01561a015}}</ref>
			Potassium nitrite reacts at an extremely slow rate with a liquid ammonia solution of ] at room temperatures, and in the presence of ] or ], to form nitrogen and ].
			==Medical uses==
			Interest in a medical role for inorganic nitrite was first aroused because of the spectacular success of organic nitrites and related compounds in the treatment of ]. While working with Butter at the ] in the 1860s, Brunton noted that the pain of angina could be lessened by ] and wrongly concluded that the pain must be due to elevated blood pressure. As a treatment for angina, the reduction of circulating blood by venesection was inconvenient. Therefore, he decided to try the effect on a patient of inhaling ], a recently synthesized compound and one that his colleague had shown lowered blood pressure in animals. Pain associated with an anginal attack disappeared rapidly, and the effect lasted for several minutes, generally long enough for the patient to recover by resting. For a time, amyl nitrite was the favored treatment for angina, but due to its volatility, it was replaced by chemically related compounds that had the same effect.<ref name="American Heart Association" />
			The effect of potassium nitrite on the nervous system, brain, spinal cord, pulse, arterial blood pressure, and respiration of healthy human volunteers was noted, as was the variability between individuals. The most significant observation was that even a small dose of <0.5 grains (≈30&nbsp;mg) given by mouth caused, at first, an increase in arterial ], followed by a moderate decrease. With larger doses, pronounced ] ensued. They also noted that potassium nitrite, however administered, had a profound effect on the appearance and oxygen-carrying capacity of the blood. They compared the biological action of potassium nitrite with that of amyl and ethyl nitrites and concluded that the similarity of action depends on the conversion of organic nitrites to ].
			<ref name="American Heart Association" />
			Solutions of acidified nitrite have been used successfully to generate NO and to induce ] in isolated ] studies, and the same reaction mechanism has been proposed to explain the biological action of ].<ref name="American Heart Association" />
			==Other uses==
			Potassium nitrite is used in the manufacturing of heat transfer salts. As ] ], potassium nitrite is a ] similar to ] and is approved for usage in the EU,<ref>UK Food Standards Agency: {{cite web |url=http://www.food.gov.uk/safereating/chemsafe/additivesbranch/enumberlist |title=Current EU approved additives and their E Numbers |access-date=2011-10-27}}</ref> USA,<ref>US Food and Drug Administration: {{cite web |url=https://www.fda.gov/Food/FoodIngredientsPackaging/FoodAdditives/ucm191033.htm#ftnT |title=Listing of Food Additives Status Part II |website=] |access-date=2011-10-27}}</ref> Australia and New Zealand<ref>Australia New Zealand Food Standards Code{{cite web |url=http://www.comlaw.gov.au/Details/F2011C00827 |title=Standard 1.2.4 - Labelling of ingredients |date=8 September 2011 |access-date=2011-10-27}}</ref> (where it is listed under its ] 249).
			==Reactivity hazards==
			When reacting with acids, potassium nitrite forms toxic nitrous oxides. Fusion with ] salts results in ] and ]. Reactions with reducing agents can result in fires and explosions.<ref name="Chemical Education Today" /> The reason for this increased reactivity correlates with the specific oxidizing character of ]. Nitrite (III) is a stronger ] than ] (V) because, at valence III, it has less ] to recover than nitrate at valence V, and so the number of electrons to capture is lower. This facilitates more efficient electronic transfer capabilities and increases the ] of the ] reaction, making nitrite a more reactive ] than nitrate. Due to this nature, nitrite salts should always be handled with care, especially in the context of ] ]. <ref name="Difference Between Nitrite and Nitrate" />
			==Storage requirements==
			Potassium nitrite is stored with other oxidizing agents but separated from flammables, combustibles, ], acids, ], ammonium compounds, amides, and other nitrogenous salts in a cool, dry, well ventilated location.<ref name="Chemical Education Today">{{cite journal|last=Division of Chemical Education|title=Potassium Nitrite|journal=Journal of Chemical Education|date=June 2008|volume=85|issue=6|pages=779|url=http://www.jce.divched.org/|doi=10.1021/ed085p779|bibcode=2008JChEd..85..779Y|access-date=2012-06-22|archive-date=2012-06-22|archive-url=https://web.archive.org/web/20120622225631/http://www.jce.divched.org/|url-status=dead}}</ref>
			== See also ==
			* ]
			* ]
			* ]
			== External links ==
			*
			{{Reflist}}
			{{Potassium compounds}}
			{{DEFAULTSORT:Potassium Nitrite}}
			]
			]
			]
			]
			]