Ammonium iron(II) sulfate, or Mohr's salt, is the inorganic compound with the formula (NH4)2Fe(SO4)2(H2O)6. Containing two different cations, Fe2+ and NH+4, it is classified as a double salt of ferrous sulfate and ammonium sulfate. It is a common laboratory reagent because it is readily crystallized, and crystals resist oxidation by air. Like the other ferrous sulfate salts, ferrous ammonium sulfate dissolves in water to give the aquo complex [Fe(H2O)6]2+, which has octahedral molecular geometry.[1] Its mineral form is mohrite.
This compound is a member of a group of double sulfates called Schönites or Tutton's salts. Tutton's salts form monoclinic crystals and have formula M2N(SO4)2·6H2O (M = various monocations). With regards to the bonding, crystals consist of octahedra [Fe(H2O)6]2+ centers, which are hydrogen bonded to sulfate and ammonium.[2]
Structure of ferrous ammonium sulfate with hydrogen bonding network highlighted (N is violet, O is red; S is orange, Fe = large red).
Mohr's salt is named after the German chemist Karl Friedrich Mohr, who made many important advances in the methodology of titration in the 19th century.
Applicationsedit
In analytical chemistry, this salt is the preferred source of ferrous ions as the solid has a long shelf life, being resistant to oxidation. This stability extends somewhat to solutions reflecting the effect of pH on the ferrous–ferric redox couple. This oxidation occurs more readily at high pH. The ammonium ions make solutions of Mohr's salt slightly acidic, which slows this oxidation process.[1][3] Sulfuric acid is commonly added to solutions to reduce oxidation to ferric iron.
It is used in the Fricke's dosimeter to measure high doses of gamma rays.[4]
Preparationedit
Mohr's salt is prepared by dissolving an equimolar mixture of hydratedferrous sulfate and ammonium sulfate in water containing a little sulfuric acid, and then subjecting the resulting solution to crystallization. Ferrous ammonium sulfate forms light green crystals. This salt, when heated, ionises to give all cations and anions present in it.
^Ephraim, Fritz (1926). Inorganic Chemistry. tr P. C. L. Thorne. London: Gurney and Jackson. pp. 484–485.
^"Ammonium Ferrous Sulphate 100 g (Mohr's Salt)". 2012. Retrieved 13 June 2013.
^Hickman, C.; Lorrain, S.; Barthe, J.R.; Portal, G. (1986). "Use of Mohr's Salt for High Level Gamma Dosimetry (Up to 108 Gy)". Radiation Protection Dosimetry. Oxford Journals. 17 (1–4): 255–257. doi:10.1093/oxfordjournals.rpd.a079818.
^Vogel, Arthur I. (1961). A Text-book of Quantitative Inorganic Analysis Including Elementary Instrumental Analysis (3 ed.). Longmans. pp. 281–282.
February 15, 2024
ammonium, iron, sulfate, mohr, salt, inorganic, compound, with, formula, containing, different, cations, classified, double, salt, ferrous, sulfate, ammonium, sulfate, common, laboratory, reagent, because, readily, crystallized, crystals, resist, oxidation, li. Ammonium iron II sulfate or Mohr s salt is the inorganic compound with the formula NH4 2Fe SO4 2 H2O 6 Containing two different cations Fe2 and NH 4 it is classified as a double salt of ferrous sulfate and ammonium sulfate It is a common laboratory reagent because it is readily crystallized and crystals resist oxidation by air Like the other ferrous sulfate salts ferrous ammonium sulfate dissolves in water to give the aquo complex Fe H2O 6 2 which has octahedral molecular geometry 1 Its mineral form is mohrite Ammonium iron II sulfate NamesIUPAC name Ammonium iron II sulfateOther names Ferrous ammonium sulfateAmmonium iron sulfateMohr s saltIdentifiersCAS Number anhydrous 10045 89 3 Yhexahydrate 7783 85 93D model JSmol Interactive imageChEBI anhydrous CHEBI 76243hexahydrate CHEBI 76181 YChemSpider anhydrous 23246 Yhexahydrate 13084980 YECHA InfoCard 100 030 125EC Number 233 151 8PubChem CID anhydrous 24863hexahydrate 15942308UNII anhydrous 9Q764AYJ9G Yhexahydrate 99A04ICQ3JCompTox Dashboard EPA DTXSID4041028InChI InChI 1S Fe 2H3N 2H2O4S c 2 1 5 2 3 4 h 2 1H3 2 H2 1 2 3 4 q 2 p 2 YKey IMBKASBLAKCLEM UHFFFAOYSA L YInChI 1 Fe 2H3N 2H2O4S c 2 1 5 2 3 4 h 2 1H3 2 H2 1 2 3 4 q 2 p 2Key IMBKASBLAKCLEM NUQVWONBAXSMILES Fe 2 O S O O O O S O O O NH4 NH4 PropertiesChemical formula Fe SO4 NH4 2 SO4 anhydrous Fe SO4 NH4 2 SO4 6H2O hexahydrate Molar mass 284 05 g mol 1 anhydrous 392 14 g mol 1 hexahydrate Appearance Blue green solidDensity 1 86 g cm3Melting point 100 to 110 C 212 to 230 F 373 to 383 K Boiling point Not applicableSolubility in water 269 g L hexahydrate HazardsGHS labelling PictogramsSignal word WarningHazard statements H315 H319 H335Precautionary statements P261 P264 P271 P280 P302 P352 P304 P340 P305 P351 P338 P312 P321 P332 P313 P337 P313 P362 P403 P233 P405 P501NFPA 704 fire diamond 200Safety data sheet SDS Fisher MSDSRelated compoundsRelated compounds Ammonium iron III sulfateExcept 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 Structure 2 Applications 3 Preparation 4 Contaminants 5 ReferencesStructure editThis compound is a member of a group of double sulfates called Schonites or Tutton s salts Tutton s salts form monoclinic crystals and have formula M2N SO4 2 6H2O M various monocations With regards to the bonding crystals consist of octahedra Fe H2O 6 2 centers which are hydrogen bonded to sulfate and ammonium 2 nbsp Structure of ferrous ammonium sulfate with hydrogen bonding network highlighted N is violet O is red S is orange Fe large red Mohr s salt is named after the German chemist Karl Friedrich Mohr who made many important advances in the methodology of titration in the 19th century Applications editIn analytical chemistry this salt is the preferred source of ferrous ions as the solid has a long shelf life being resistant to oxidation This stability extends somewhat to solutions reflecting the effect of pH on the ferrous ferric redox couple This oxidation occurs more readily at high pH The ammonium ions make solutions of Mohr s salt slightly acidic which slows this oxidation process 1 3 Sulfuric acid is commonly added to solutions to reduce oxidation to ferric iron It is used in the Fricke s dosimeter to measure high doses of gamma rays 4 Preparation editMohr s salt is prepared by dissolving an equimolar mixture of hydrated ferrous sulfate and ammonium sulfate in water containing a little sulfuric acid and then subjecting the resulting solution to crystallization Ferrous ammonium sulfate forms light green crystals This salt when heated ionises to give all cations and anions present in it Contaminants editCommon impurities include magnesium nickel manganese lead and zinc many of which form isomorphous salts 5 References edit a b Greenwood Norman N Earnshaw Alan 1997 Chemistry of the Elements 2nd ed Butterworth Heinemann ISBN 978 0 08 037941 8 Ephraim Fritz 1926 Inorganic Chemistry tr P C L Thorne London Gurney and Jackson pp 484 485 Ammonium Ferrous Sulphate 100 g Mohr s Salt 2012 Retrieved 13 June 2013 Hickman C Lorrain S Barthe J R Portal G 1986 Use of Mohr s Salt for High Level Gamma Dosimetry Up to 108 Gy Radiation Protection Dosimetry Oxford Journals 17 1 4 255 257 doi 10 1093 oxfordjournals rpd a079818 Vogel Arthur I 1961 A Text book of Quantitative Inorganic Analysis Including Elementary Instrumental Analysis 3 ed Longmans pp 281 282 Retrieved from https en wikipedia org w index php title Ammonium iron II sulfate amp oldid 1180053494, wikipedia, wiki, book, books, library,
