Ammonium heptamolybdate is the inorganic compound whose chemical formula is (NH4)6Mo7O24, normally encountered as the tetrahydrate. A dihydrate is also known. It is a colorless solid, often referred to as ammonium paramolybdate or simply as ammonium molybdate, although "ammonium molybdate" can also refer to ammonium orthomolybdate, (NH4)2MoO4, and several other compounds. It is one of the more common molybdenum compounds.[1]
Ammonium heptamolybdate is easily prepared by dissolving molybdenum trioxide in an excess of aqueous ammonia and evaporating the solution at room temperature. While the solution evaporates, the excess of ammonia escapes. This method results in the formation of six-sided transparent prisms of the tetrahydrate of ammonium heptamolybdate.[2]
Solutions of ammonium paramolybdate react with acids to form molybdic acid and an ammonium salt. The pH value of a concentrated solution will lie between 5 and 6.
Structureedit
The compound was first analyzed crystallographically by Lindqvist, but has been reanalyzed.[3] All Mo centers are octahedral. Some oxide ligands are terminal, some doubly bridging, and a few are triply bridging ligands.
as a negative stain in biological electron microscopy, typically in the 3–5% (vol/vol) concentration range and in the presence of trehalose;[5] or at saturated concentration to perform cryo-negative staining.[6][7]
For the detection of recreational drugs as a component of the Froehde reagent
Related compoundsedit
Potassium heptamolybdate, also obtained as the tetrahydrate, is very similar to the ammonium salt.[3]
Safetyedit
Molybdates are typically of low toxicity, so much so that few reports of incidents have ever been reported.[1]
^L. Svanberg & H. Struve, J. pr. Ch.44 [1848], p. 282; cited in Gmelin's Handbuch für Anorganische Chemie, 53, p. 255.
^ abEvans, H.T., Jr.; Gatehouse, B. M.; Leverett, P. "Crystal Structure of the Heptamolybdate(VI) (paramolybdate) ion, (Mo7O24)6−, in the ammonium and potassium tetrahydrate salts" Journal of the Chemical Society. Dalton Transactions, Inorganic Chemistry1975, p.505-p514.
^Parsons, T.; Maita, V. & Lalli, C. (1984). A manual of chemical and biological methods for seawater analysis. Oxford: Pergamon.
^Harris, J. R. and Horne, R. W. 1991. "Negative staining", in Harris J. R. (Ed.), Electron Microscopy in Biology, Oxford University Press, Oxford.
^Adrian, Marc; Dubochet, Jacques; Fuller, Stephen D.; Harris, J. Robin (1998). "Cryo-negative staining". Micron. 29 (2–3): 145–160. doi:10.1016/S0968-4328(97)00068-1. PMID 9684350.
ammonium, heptamolybdate, inorganic, compound, whose, chemical, formula, 6mo7o24, normally, encountered, tetrahydrate, dihydrate, also, known, colorless, solid, often, referred, ammonium, paramolybdate, simply, ammonium, molybdate, although, ammonium, molybdat. Ammonium heptamolybdate is the inorganic compound whose chemical formula is NH4 6Mo7O24 normally encountered as the tetrahydrate A dihydrate is also known It is a colorless solid often referred to as ammonium paramolybdate or simply as ammonium molybdate although ammonium molybdate can also refer to ammonium orthomolybdate NH4 2MoO4 and several other compounds It is one of the more common molybdenum compounds 1 Ammonium heptamolybdate NamesIUPAC name Ammonium docosaoxoheptamolybdate 6 Other names Ammonium molybdateAmmonium paramolybdate see text IdentifiersCAS Number 12027 67 7 Y12054 85 2 tetrahydrate Y3D model JSmol Interactive imageInteractive imageChemSpider 23786 YECHA InfoCard 100 031 553EC Number 234 320 9PubChem CID 71306766UNII 21Y68J178E YOGI154X474 tetrahydrate YCompTox Dashboard EPA DTXSID40858865 DTXSID5036896 DTXSID40858865InChI InChI 1S 7Mo 6H3N 24H2O h 6 1H3 24 1H2 YKey QGAVSDVURUSLQK UHFFFAOYSA N YInChI 1 7Mo 6H3N 24H2O h 6 1H3 24 1H2Key QGAVSDVURUSLQK UHFFFAOYACSMILES NH4 NH4 NH4 NH4 NH4 NH4 O Mo O O O O Mo O O O O Mo O O O NH4 NH4 NH4 Mo 3479 12 O 1 Mo 25 O O O Mo 1 10 O O O Mo 11 O O O Mo 8 O O O Mo 6 O O O Mo O O O2 O3 O 456 O 78 O 9 10 11 O 12 NH4 NH4 NH4 PropertiesChemical formula NH4 6Mo7O24Molar mass 1163 9 g mol1235 86 g mol tetrahydrate Appearance white solidDensity 2 498 g cm3Melting point 90 C loses water molecule 190 C decomp Solubility in water 65 3 g 100 ml tetrahydrate HazardsOccupational safety and health OHS OSH Main hazards IrritantNFPA 704 fire diamond 200Flash point Non flammableSafety data sheet SDS External MSDSRelated compoundsOther anions Ammonium orthomolybdateAmmonium dimolybdateOther cations Potassium paramolybdateRelated compounds Molybdenum VI oxideMolybdic acidExcept where otherwise noted data are given for materials in their standard state at 25 C 77 F 100 kPa N verify what is Y N Infobox references Contents 1 Synthesis 2 Structure 3 Uses 4 Related compounds 5 Safety 6 References 7 See alsoSynthesis editAmmonium heptamolybdate is easily prepared by dissolving molybdenum trioxide in an excess of aqueous ammonia and evaporating the solution at room temperature While the solution evaporates the excess of ammonia escapes This method results in the formation of six sided transparent prisms of the tetrahydrate of ammonium heptamolybdate 2 Solutions of ammonium paramolybdate react with acids to form molybdic acid and an ammonium salt The pH value of a concentrated solution will lie between 5 and 6 Structure editThe compound was first analyzed crystallographically by Lindqvist but has been reanalyzed 3 All Mo centers are octahedral Some oxide ligands are terminal some doubly bridging and a few are triply bridging ligands nbsp The salt contains the heptamolybdate hexaanion Uses editas an analytical reagent to measure the amount of phosphates silicates arsenates and lead in aqueous solution e g pigments river water sea water etc 4 in the production of molybdenum metal and ceramics in the preparation of dehydrogenation and desulfurization catalysts in the fixing of metals in electroplating in fertilizers for crops as a negative stain in biological electron microscopy typically in the 3 5 vol vol concentration range and in the presence of trehalose 5 or at saturated concentration to perform cryo negative staining 6 7 For the detection of recreational drugs as a component of the Froehde reagentRelated compounds editPotassium heptamolybdate also obtained as the tetrahydrate is very similar to the ammonium salt 3 Safety editMolybdates are typically of low toxicity so much so that few reports of incidents have ever been reported 1 References edit a b Sebenik Roger F et al 2000 Molybdenum and Molybdenum Compounds Ullmann s Encyclopedia of Industrial Chemistry Weinheim Wiley VCH doi 10 1002 14356007 L Svanberg amp H Struve J pr Ch 44 1848 p 282 cited in Gmelin s Handbuch fur Anorganische Chemie 53 p 255 a b Evans H T Jr Gatehouse B M Leverett P Crystal Structure of the Heptamolybdate VI paramolybdate ion Mo7O24 6 in the ammonium and potassium tetrahydrate salts Journal of the Chemical Society Dalton Transactions Inorganic Chemistry1975 p 505 p514 Parsons T Maita V amp Lalli C 1984 A manual of chemical and biological methods for seawater analysis Oxford Pergamon Harris J R and Horne R W 1991 Negative staining in Harris J R Ed Electron Microscopy in Biology Oxford University Press Oxford Adrian Marc Dubochet Jacques Fuller Stephen D Harris J Robin 1998 Cryo negative staining Micron 29 2 3 145 160 doi 10 1016 S0968 4328 97 00068 1 PMID 9684350 De Carlo S El Bez C Alvarez Rua C Borge J Dubochet J 2002 Cryo negative staining reduces electron beam sensitivity of vitrified biological particles Journal of Structural Biology 138 3 216 226 doi 10 1016 S1047 8477 02 00035 7 PMID 12217660 See also editPhosphate test aka Deniges method links to here Retrieved from https en wikipedia org w index php title Ammonium heptamolybdate amp oldid 1059831449, wikipedia, wiki, book, books, library,
