Iron(II) nitrate

Summary

Iron(II) nitrate is the nitrate salt of iron(II). It is commonly encountered as the green hexahydrate, Fe(NO3)2·6H2O, which is a metal aquo complex. The salt is soluble in water serves as a ready source of ferrous ions.

Iron(II) nitrate
FerrousNitrateHydrate.svg
Iron(II) nitrate hexahydrate.jpg
Names
Other names
  • Ferrous nitrate
Identifiers
  • 14013-86-6
  • 13520-68-8 hexahydrate
ChemSpider
  • 7991154
  • 9815404
  • DTXSID70431140 Edit this at Wikidata
Properties
Fe(NO3)2
Molar mass 179.86 g/mol[1]
Appearance Green crystals (hexahydrate)
Melting point 60 °C (140 °F; 333 K)[2] (decomposes)
87.525 g/100 mL
Structure
Orthorhombic[3]
Hazards
Lethal dose or concentration (LD, LC):
428 mg/kg (subcutaneous, rabbit)[4]
Related compounds
Other anions
Iron(II) phosphate
Other cations
Manganese(II) nitrate
Cobalt(II) nitrate
Related compounds
Iron(III) nitrate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

StructureEdit

No structure of any salt Fe(NO3)2·xH2O has been determined by X-ray crystallography. Nonetheless, the nature of the aquo complex [Fe(H2O)6]2+ is well known and relatively insensitive to the anion. The Fe-O distances are longer for [Fe(H2O)6]2+ (2.13 Å) than for the ferric analogue [Fe(H2O)6]3+ (1.99 Å).[5] Both [Fe(H2O6]n+ complexes are high spin, which results in pale colors, paramagnetism, and weak Fe-O bonds.

 
The solubility graph of iron(II) nitrate

ProductionEdit

Iron(II) nitrate can be produced in multiple ways such as the reaction of iron metal with cold dilute nitric acid:

3 Fe + 8 HNO3 + 12 H2O → 3 Fe(NO3)2(H2O)6 + 2 NO

If this reaction is conducted below -10 °C, nonahydrate is produced. It readily releases water to give the hexahydrate.[6]

The above reaction can also co-produce ferric nitrate. For a purer product, it can also be produced by the reaction of hydrazine nitrate and ferric nitrate at 40 °C:[7]

4 Fe(NO3)3 + N2H5NO3 → 4 Fe(NO3)2 + N2 + 4HNO3

To prevent from the backward reaction from happening, copper(II) nitrate is added.[7]

ReferencesEdit

  1. ^ "Iron nitrate". PubChem. PubChem. Retrieved 14 February 2021.
  2. ^ Lide, David, ed. (2004). "4". CRC Handbook of Chemistry and Physics (Hardcover) (85th ed.). Taylor & Francis. p. 62. ISBN 9780849304859.
  3. ^ Herman Francis Mark; Anthony Standen (1963). Standen, Anthony (ed.). Encyclopedia of Chemical Technology. Interscience Publishers. Retrieved 16 February 2021.
  4. ^ National Institute for Occupational Safety and Health (1981). Registry of Toxic Effects of Chemical Substances. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control, National Institute for Occupational Safety and Health. p. 548. Retrieved 16 February 2021.
  5. ^ Hair, Neil J.; Beattie, James K. (1977). "Structure of Hexaaquairon(III) Nitrate Trihydrate. Comparison of Iron(II) and Iron(III) Bond Lengths in High-Spin Octahedral Environments". Inorganic Chemistry. 16 (2): 245–250. doi:10.1021/ic50168a006.
  6. ^ "Iron(II) nitrate". Chemical Book. Chemical Book. Retrieved 14 February 2021.
  7. ^ a b D. G. Karraker (1981). "Cu(II) - Catalyzed Hydrazine Reduction of Ferric Nitrate" (PDF). United States Department of Energy. doi:10.2172/5658572. {{cite journal}}: Cite journal requires |journal= (help)