magnesium chlorate
{{Chembox
| Reference =
| Name =
| IUPACName = Magnesium dichlorate hexahydrate
| PIN =
| SystematicName = Magnesium dichlorate
| OtherNames = {{Unbulleted list
| Magnesium(II) chlorate
}}
| data page pagename =
| ImageFile = Mg(aq6(ClO3)2.svg
| ImageSize =
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| Section1 = {{Chembox Identifiers
| index4_label = (hexahydrate)
| index2_label = (dihydrate)
| 3DMet =
| Abbreviations =
| Beilstein =
| CASNo = 10326-21-3
| CASNo2 = 36355-97-2
| CASNo4 = 7791-19-7
| ChEBI =
| ChemSpiderID = 64853748
| ChemSpiderID2 = 80564724
| ChemSpiderID4 = 128878
| DTXSID4 = DTXSID30999110
| EC_number = 233-711-1
| EC_number_Comment=
| Gmelin =
| KEGG =
| MeSHName =
| PubChem = 25155
| PubChem2 = 71437298
| PubChem4 = 146100
| RTECS =
| SMILES = Cl(=O)(=O)[O-].Cl(=O)(=O)[O-].[Mg+2]
| UNII = M536P01U3N
| UNNumber = 2723
| InChI = 1S/2ClHO3.Mg/c2*2-1(3)4;/h2*(H,2,3,4);/q;;+2/p-2
| InChIKey = NNNSKJSUQWKSAM-UHFFFAOYSA-L
| SMILES2 = O.O.[Mg+2].[O-]Cl(=O)=O.[O-]Cl(=O)=O
| InChI2 = 1S/2ClHO3.Mg.2H2O/c2*2-1(3)4;;;/h2*(H,2,3,4);;2*1H2/q;;+2;;/p-2
| InChIKey2 = YTXOASNCVSJHNM-UHFFFAOYSA-L
| InChI4=1S/2ClHO3.Mg.6H2O/c2*2-1(3)4;;;;;;;/h2*(H,2,3,4);;6*1H2/q;;+2;;;;;;/p-2
| InChIKey4 = XKPLAISKKLSAQQ-UHFFFAOYSA-L
| SMILES4 = O.O.O.O.O.O.[O-]Cl(=O)=O.[O-]Cl(=O)=O.[Mg+2]
}}
| Section2 = {{Chembox Properties
| AtmosphericOHRateConstant =
| Appearance = White crystalline solid
| BoilingPt =
| BoilingPtC = 120
| BoilingPt_notes= (decomposition)
| Density = 1.747 g/cm3 (hexahydrate)
| Formula = Mg(ClO3)2
| HenryConstant =
| LogP =
| MolarMass = 191.20 g/mol
| MeltingPt =
| MeltingPtC = 35
| MeltingPt_notes=
| pKa =
| pKb =
| Solubility = 114 g/100 ml (0 °C)
123 g/100 ml (10 °C)
135 g/100 ml (20 °C)
155 g/100 ml (30 °C)
178 g/100 ml (50 °C)
242 g/100 ml (60 °C)
268 g/100 ml (100 °C)
| SolubleOther = Soluble
| Solvent = acetone
| VaporPressure =
}}
| Section3 = {{Chembox Structure
| CrystalStruct = Monoclinic
| SpaceGroup = P21/c
| PointGroup =
| LattConst_a = 6.39 Å
| LattConst_b = 6.51 Å
| LattConst_c = 13.90 Å
| LattConst_alpha =
| LattConst_beta = 100.3
| LattConst_gamma =
| LattConst_ref =
| LattConst_Comment =
| UnitCellVolume = 590.1 Å3
| UnitCellFormulas =
| Coordination =
}}
| Section4 = {{Chembox Thermochemistry
| DeltaGf =
| DeltaHc =
| DeltaHf =
| Entropy =
| HeatCapacity =
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| Section7 = {{Chembox Hazards
| AutoignitionPt =
| ExploLimits =
| FlashPt =
| LD50 = 6348 mg/kg (rat, oral)
| LC50 =
| MainHazards =
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| ExternalSDS =
| GHSPictograms = {{GHS07}}
| GHSSignalWord = Warning
| HPhrases = {{h-phrases|302|332}}
| PPhrases =
}}
| Section9 = {{Chembox Related
| OtherAnions =
| OtherCations = Calcium chlorate
Strontium chlorate
Barium chlorate
| OtherFunction =
| OtherFunction_label =
| OtherCompounds =
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}}
Magnesium chlorate refers to inorganic compounds with the chemical formula Mg(ClO3)2(H2O)x. The anhydrous (x = 0), dihydrate (x = 2), and hexahydrate (x = 6) are known. These are thermally labile white solids. The hexahydrate has been identified on the Martian surface.{{cite journal |doi=10.1038/ngeo2546 |title=Spectral evidence for hydrated salts in recurring slope lineae on Mars |date=2015 |last1=Ojha |first1=Lujendra |last2=Wilhelm |first2=Mary Beth |last3=Murchie |first3=Scott L. |last4=McEwen |first4=Alfred S. |last5=Wray |first5=James J. |last6=Hanley |first6=Jennifer |last7=Massé |first7=Marion |last8=Chojnacki |first8=Matt |journal=Nature Geoscience |volume=8 |issue=11 |pages=829–832 |bibcode=2015NatGe...8..829O }}
Production
Samples of magnesium chlorate were first claimed in 1920 as the result of treating magnesium oxide with chlorine. A more modern method involves electrolysis of magnesium chloride.{{cite book |author1=Herbert Maxim |title=The electrolytic production of magnesium chlorate and perchlorate |date=1948 |publisher=University of Southern California |location=the Department of Chemical Engineering |language=English}} The magnesium chlorate can be purified by exploiting its solubility in acetone.
A more simple method of production is the reaction of barium chlorate and magnesium sulfate:
:Ba(ClO3)2 + MgSO4 → BaSO4↓ + Mg(ClO3)2
The precipitated barium sulfate is filtered to yield a solution of magnesium chlorate, which when evaporated, yields crystals of the hexahydrate.
Properties
The hexahydrate Mg(ClO3)2·6H2O decomposes to the tetrahydrate at 35 °C. At 65 °C, it dehydrates to the dihydrate, then at 80 °C forms a basic salt. If further heated to 120 °C it decomposes to water, oxygen, chlorine, and magnesium oxide.{{cite book |author1=Joseph William Mellor |title=Supplement to Mellor's Comprehensive Treatise on Inorganic and Theoretical Chemistry: suppl. 3. K, Rb, Cs, Fr |date=1922 |publisher=Longmans, Green and Company}}
As confirmed by X-ray crystallography, the di- and hexahydrates feature octahedral Mg2+ centers. The other ligands are water, exclusively in the hexahydrate. In the dihydrate, chlorate is also coordinated and functions as a bridging ligand.{{cite journal|journal=Bulgarian Chemical Communications|volume=45|pages= 543–548|year=2013|title=Synthesis and Crystal Structure of Magnesium Chlorate Dihydrate and Magnesium Chlorate Hexahydrate|first1=K|last1=Kossev|first2=L.|last2=Tsvetanova|first3=L.|last3=Dimowa|first4=R.|last4=Nikolova|first5=B.|last5=Shivachev}}
Uses
Magnesium(II) chlorate is used as a powerful desiccant and a defoliant for cotton, potato, and rice. It is also found as a lubricant in eye drops as an inactive ingredient.{{cite web |title=MAGNESIUM CHLORATE |url=https://drugs.ncats.io/substance/M536P01U3N#general |website=National Center for Advancing Translational Sciences |publisher=U.S. Department of Health & Human Services |access-date=27 August 2021 |language=English}}
Hazards
Magnesium chlorate is an oxidizer and can in principle form explosive mixtures.