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{{chembox {{chembox
| Verifiedfields = changed
| verifiedrevid = 408041297
| Watchedfields = changed
| verifiedrevid = 448711409
| ImageFile = Potassium-oxide-3D-vdW.png | ImageFile = Potassium-oxide-3D-vdW.png
| ImageName = Potassium Oxide spacefilling model
| ImageSize = 200px
| ImageName = Potassium oxide | IUPACName = potassium oxide
| SystematicName = potassium oxidopotassium
| IUPACName = Potassium oxide
| OtherNames = Potassium monoxide | OtherNames = ], dipotassium oxide
| Section1 = {{Chembox Identifiers |Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 12136-45-7
| CASNo = 12136-45-7
| CASNo_Ref = {{cascite|correct|CAS}}
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| UNNumber = 2033
| ChemSpiderID = 23354117
| ChemSpiderID_Comment =
| ChEBI = 88321
| EC_number = 235-227-6
| PubChem = 25520
| UNNumber = 2033
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 58D606078H
| MeSHName = Potassium+oxide
| SMILES = O()
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| StdInChI = 1S/2K.O
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| StdInChIKey = NOTVAPJNGZMVSD-UHFFFAOYSA-N
}} }}
| Section2 = {{Chembox Properties |Section2={{Chembox Properties
| K=2 | O=1
| Formula = K<sub>2</sub>O
| MolarMass = 94.20 g/mol | Appearance = Pale yellow solid
| Odor = Odorless
| Appearance = pale yellow solid
| Density = 2.32 g/cm<sup>3</sup> (20 °C)<ref name=chemister>{{cite web|last = Anatolievich|first = Kiper Ruslan|website=chemister.ru|url = http://chemister.ru/Database/properties-en.php?dbid=1&id=516|title = potassium oxide|access-date = 2014-07-04}}</ref><br> 2.13 g/cm<sup>3</sup> (24 °C)<ref name=crc />
| Density = 2.35 g/cm<sup>3</sup>
| Solubility = Reacts forming ] | Solubility = Reacts<ref name=chemister /> forming ]
| SolubleOther = Soluble in ]<ref name=crc />
| MeltingPt = >350 °C decomp.
| MeltingPtC = 740
| MeltingPt_ref = <ref name=crc>{{CRC90}}</ref>
}} }}
| Section3 = {{Chembox Structure |Section3={{Chembox Structure
| CrystalStruct = ] ], ]<ref name=socacs>{{cite book|page = 25|title = The Structure of Crystals|edition = 2nd|year = 1935|last = Wyckoff|first = Ralph W.G.|publisher = Reinhold Publishing Corp.|work = American Chemical Society}}</ref>
| CrystalStruct = ] (cubic), ]
| SpaceGroup = Fm<u style="text-decoration:overline">3</u>m, No. 225 | SpaceGroup = Fm{{overline|3}}m, No. 225<ref name=socacs />
| Coordination = Tetrahedral (K<sup>+</sup>); cubic (O<sup>2–</sup>) | Coordination = Tetrahedral (K<sup>+</sup>)<br> Cubic (O<sup>2−</sup>)
| LattConst_a = 6.436&nbsp;Å<ref name=socacs />
| LattConst_a =
| LattConst_alpha = | LattConst_alpha = 90
}} }}
| Section4 = {{Chembox Thermochemistry |Section4={{Chembox Thermochemistry
| DeltaHf = −363.17 kJ/mol<ref name=chemister /><ref name=nist>{{nist|name=Dipotassium oxide|id=12136457|accessdate=2014-07-04|mask=FFFF|units=SI}}</ref>
| DeltaHf =
| Entropy = 94.03 J/mol·K<ref name=nist />
| Entropy =
| HeatCapacity = 83.62 J/mol·K<ref name=nist />
| HeatCapacity =
| DeltaGf = −322.1 kJ/mol<ref name=chemister />
}} }}
| Section7 = {{Chembox Hazards |Section7={{Chembox Hazards
| ExternalMSDS = | ExternalSDS =
| MainHazards = Corrosive, reacts violently with water
| EUIndex = Not listed
| NFPA-H = 3
| MainHazards = Corrosive, reacts violently with water
| NFPA-H = | NFPA-F = 0
| NFPA-F = | NFPA-R = 1
| NFPA-R = | NFPA-S = W
| GHSPictograms = {{GHS05}}
| NFPA-O =
| GHSSignalWord = Danger
| FlashPt = Non-flammable
| HPhrases = {{H-phrases|314}}
| PPhrases = {{P-phrases|260|264|280|301+330+331|303+361+353|304+340|305+351+338|310|321|363|405|501}}
}} }}
| Section8 = {{Chembox Related |Section8={{Chembox Related
| OtherAnions = ] | OtherAnions = ]<br>]<br>]<br>]
| OtherCations = ]<br/>]<br/>]<br/>] | OtherCations = ]<br> ]<br> ]<br> ]
| OtherFunctn = ]<br/>] | OtherFunction = ]<br> ]<br>]
| Function = ] ]s | OtherFunction_label = ] ]s
| OtherCpds = ] | OtherCompounds = ]
}} }}
}} }}

'''Potassium oxide''' is an ionic ] of ] and ]. This pale yellow solid, the simplest oxide of potassium, is a rarely encountered, highly reactive species. Some materials of commerce, such as fertilizers and cements, are assayed assuming the percent composition that would be equivalent to K<sub>2</sub>O.
'''Potassium oxide''' (]]) is an ionic ] of ] and ]. It is a ]. This pale yellow solid is the simplest oxide of potassium. It is a highly reactive compound that is rarely encountered. Some industrial materials, such as fertilizers and cements, are assayed assuming the percent composition that would be equivalent to K<sub>2</sub>O.


==Production== ==Production==
Potassium oxide is produced from the reaction of oxygen and potassium; this reaction affords ], K<sub>2</sub>O<sub>2</sub>. Treatment of the peroxide with potassium produces the oxide:<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.</ref> Potassium oxide is produced from the reaction of oxygen and potassium; this reaction affords ], K<sub>2</sub>O<sub>2</sub>. Treatment of the peroxide with potassium produces the oxide:<ref>Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. {{ISBN|0-12-352651-5}}.</ref>
: K<sub>2</sub>O<sub>2</sub> + 2 K → 2 K<sub>2</sub>O : <chem>K2O2 + 2 K -> 2 K2O</chem>

Alternatively and more conveniently, K<sub>2</sub>O is synthesized by heating ] with metallic potassium: Alternatively and more conveniently, K<sub>2</sub>O is synthesized by heating ] with metallic potassium:
:<chem>2KNO3 + 10K -> 6K2O + N2 (^)</chem>
:2 KNO<sub>3</sub> + 10 K → 6 K<sub>2</sub>O + N<sub>2</sub>

] cannot be further dehydrated to the oxide.
Other possibility is to heat potassium peroxide at 500&nbsp;°C which decomposes at that temperature giving pure potassium oxide and oxygen.

:<chem>2K2O2 -> 2K2O + O2 (^)</chem>

] cannot be further dehydrated to the oxide but it can react with molten potassium to produce it, releasing ] as a byproduct.

:<chem>2KOH + 2K <=> 2K2O + H2 (^)</chem>


==Properties and reactions== ==Properties and reactions==
K<sub>2</sub>O crystallises in the [[Fluorite structure|
K<sub>2</sub>O crystallises in the antifluorite structure. In this motif the positions of the ]s and ]s are reversed relative to their positions in ], with potassium ions coordinated to 4 oxide ions and oxide ions coordinated to 8 potassium.<ref>{{Citation | title = Gitterstruktur der oxyde, sulfide, selenide und telluride des lithiums, natriums und kaliums | author = ]; Harder, A.; Dauth B. | journal = ] | year = 1934 | volume = 40 | pages = 588–93}}</ref><ref>Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.</ref> K<sub>2</sub>O is a basic oxide and reacts with water violently to produce the caustic ]. It is ] and will absorb water from the atmosphere, initiating this vigorous reaction.
antifluorite structure]]. In this motif the positions of the ]s and ]s are reversed relative to their positions in ], with potassium ions coordinated to 4 oxide ions and oxide ions coordinated to 8 potassium.<ref>{{cite journal|title = Gitterstruktur der oxide, sulfide, selenide und telluride des lithiums, natriums und kaliums|journal = Zeitschrift für Elektrochemie und Angewandte Physikalische Chemie|year = 1934|volume = 40|pages = 588–93|last1 = Zintl|first1 = E.|last2 = Harder|first2 = A.|author3 = Dauth B.| issue=8 | doi=10.1002/bbpc.19340400811 |author-link1 = Eduard Zintl}}</ref><ref>Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. {{ISBN|0-19-855370-6}}.</ref> K<sub>2</sub>O is a basic oxide and reacts with water violently to produce the caustic ]. It is ] and will absorb water from the atmosphere, initiating this vigorous reaction.


==Term use in industry==
==Fertilizers==
The chemical formula K<sub>2</sub>O is used in the N-P-K (nitrogen-phosphorus-potassium) numbers on the labels of ]s. Although K<sub>2</sub>O is the correct formula for potassium oxide, potassium oxide is not used as a fertilizer in these products. Normally, ], ], or ] is used as a fertilizer source for potassium. The percentage of K<sub>2</sub>O given on the label only represents the amount of potassium in the fertilizer if it was in the form of potassium oxide. Potassium oxide is about 83% ] by weight, but ], for instance, is only 52% ] by weight. ] provides less ] than an equal amount of potassium oxide. Thus, if a fertilizer is 30% ] by weight, its standard ] rating, based on potassium oxide, would be only 19%. The chemical formula K<sub>2</sub>O (or simply 'K') is used in several industrial contexts: the ] numbers for ]s, in ], and in ]. Potassium oxide is often not used directly in these products, but the amount of potassium is reported in terms of the K<sub>2</sub>O equivalent for whatever type of ] was used, such as ]. For example, potassium oxide is about 83% ] by weight, while ] is only 52%. ] provides less ] than an equal amount of potassium oxide. Thus, if a fertilizer is 30% ] by weight, its standard ] rating, based on potassium oxide, would be only 18.8%.


==References== ==References==
{{reflist}}
<references />

==External links==
{{Commons category|Potassium oxide}}


{{Potassium compounds}} {{Potassium compounds}}
{{Oxides}}


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Latest revision as of 09:43, 22 June 2024

Potassium oxide
Potassium Oxide spacefilling model
Names
IUPAC name potassium oxide
Systematic IUPAC name potassium oxidopotassium
Other names potash, dipotassium oxide
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.032.012 Edit this at Wikidata
EC Number
  • 235-227-6
MeSH Potassium+oxide
PubChem CID
UNII
UN number 2033
CompTox Dashboard (EPA)
InChI
  • InChI=1S/2K.OKey: NOTVAPJNGZMVSD-UHFFFAOYSA-N
SMILES
  • O()
Properties
Chemical formula K2O
Molar mass 94.196 g·mol
Appearance Pale yellow solid
Odor Odorless
Density 2.32 g/cm (20 °C)
2.13 g/cm (24 °C)
Melting point 740 °C (1,360 °F; 1,010 K)
Solubility in water Reacts forming KOH
Solubility Soluble in diethyl ether
Structure
Crystal structure Antifluorite cubic, cF12
Space group Fm3m, No. 225
Lattice constant a = 6.436 Åα = 90°, β = 90°, γ = 90°
Coordination geometry Tetrahedral (K)
Cubic (O)
Thermochemistry
Heat capacity (C) 83.62 J/mol·K
Std molar
entropy (S298) 		94.03 J/mol·K
Std enthalpy of
formation (ΔfH298) 		−363.17 kJ/mol
Gibbs free energy (ΔfG) −322.1 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards Corrosive, reacts violently with water
GHS labelling:
Pictograms GHS05: Corrosive
Signal word Danger
Hazard statements H314
Precautionary statements P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard W: Reacts with water in an unusual or dangerous manner. E.g. sodium, sulfuric acid
3 0 1W
Safety data sheet (SDS) ICSC 0769
Related compounds
Other anions Potassium sulfide
Potassium selenide
Potassium telluride
Potassium polonide
Other cations Lithium oxide
Sodium oxide
Rubidium oxide
Caesium oxide
Related potassium oxides Potassium peroxide
Potassium superoxide
Potassium ozonide
Related compounds Potassium hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

Potassium oxide (K2O) is an ionic compound of potassium and oxygen. It is a base. This pale yellow solid is the simplest oxide of potassium. It is a highly reactive compound that is rarely encountered. Some industrial materials, such as fertilizers and cements, are assayed assuming the percent composition that would be equivalent to K2O.

Production

Potassium oxide is produced from the reaction of oxygen and potassium; this reaction affords potassium peroxide, K2O2. Treatment of the peroxide with potassium produces the oxide:

K 2 O 2 + 2 K ⟶ 2 K 2 O {\displaystyle {\ce {K2O2 + 2 K -> 2 K2O}}}

Alternatively and more conveniently, K2O is synthesized by heating potassium nitrate with metallic potassium:

2 KNO 3 + 10 K ⟶ 6 K 2 O + N 2 ↑ {\displaystyle {\ce {2KNO3 + 10K -> 6K2O + N2 (^)}}}

Other possibility is to heat potassium peroxide at 500 °C which decomposes at that temperature giving pure potassium oxide and oxygen.

2 K 2 O 2 ⟶ 2 K 2 O + O 2 ↑ {\displaystyle {\ce {2K2O2 -> 2K2O + O2 (^)}}}

Potassium hydroxide cannot be further dehydrated to the oxide but it can react with molten potassium to produce it, releasing hydrogen as a byproduct.

2 KOH + 2 K ↽ − − ⇀ 2 K 2 O + H 2 ↑ {\displaystyle {\ce {2KOH + 2K <=> 2K2O + H2 (^)}}}

Properties and reactions

K2O crystallises in the antifluorite structure. In this motif the positions of the anions and cations are reversed relative to their positions in CaF2, with potassium ions coordinated to 4 oxide ions and oxide ions coordinated to 8 potassium. K2O is a basic oxide and reacts with water violently to produce the caustic potassium hydroxide. It is deliquescent and will absorb water from the atmosphere, initiating this vigorous reaction.

Term use in industry

The chemical formula K2O (or simply 'K') is used in several industrial contexts: the N-P-K numbers for fertilizers, in cement formulas, and in glassmaking formulas. Potassium oxide is often not used directly in these products, but the amount of potassium is reported in terms of the K2O equivalent for whatever type of potash was used, such as potassium carbonate. For example, potassium oxide is about 83% potassium by weight, while potassium chloride is only 52%. Potassium chloride provides less potassium than an equal amount of potassium oxide. Thus, if a fertilizer is 30% potassium chloride by weight, its standard potassium rating, based on potassium oxide, would be only 18.8%.

References

  1. ^ Anatolievich, Kiper Ruslan. "potassium oxide". chemister.ru. Retrieved 2014-07-04.
  2. ^ Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0.
  3. ^ Wyckoff, Ralph W.G. (1935). The Structure of Crystals (2nd ed.). Reinhold Publishing Corp. p. 25. {{cite book}}: |work= ignored (help)
  4. ^ Dipotassium oxide in Linstrom, Peter J.; Mallard, William G. (eds.); NIST Chemistry WebBook, NIST Standard Reference Database Number 69, National Institute of Standards and Technology, Gaithersburg (MD) (retrieved 2014-07-04)
  5. Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  6. Zintl, E.; Harder, A.; Dauth B. (1934). "Gitterstruktur der oxide, sulfide, selenide und telluride des lithiums, natriums und kaliums". Zeitschrift für Elektrochemie und Angewandte Physikalische Chemie. 40 (8): 588–93. doi:10.1002/bbpc.19340400811.
  7. Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.

External links

Potassium compounds
H, (pseudo)halogens
chalcogens
pnictogens
B, C group
transition metals
organic
Oxides
Mixed oxidation states
+1 oxidation state
+2 oxidation state
+3 oxidation state
+4 oxidation state
+5 oxidation state
+6 oxidation state
+7 oxidation state
+8 oxidation state
Related
Oxides are sorted by oxidation state. Category:Oxides
Categories: