Iron filings are very small pieces of iron, used in scientific demonstrations to show the direction of a magnetic field. Iron represents magnetic properties, has a high hardness and density, is used in many applications and accounts for 95% by weight of the world's production of the metal.

IDENTIFICATION AND PROPERTIES

Name: Iron filings
Synonyms: Metallic iron, elemental iron.
CAS: 7439-89-6
EC: 231-096-4

• Physical state (20ºC): Solid - filings
• Colour: grey (metallic).
• Odour: Odourless.
• Starting point/boiling point/boiling range: 2861°C
• Vapour pressure: 1.0 .
• Evaporation rate: N.D. Non-volatile.
• Flammability: Material not readily flammable. Dust is finely combustible.
• Flash point: According to column 2 of Annex VII of REACH, the study is not necessary as the substance is inorganic.
• Self-ignition temperature: 350°C at 1013 hPa (ECHA) (relative self-ignition temperature of solids).
• Melting point: 1530ºC
• pH: N.A. Insoluble in water.
• Kinematic viscosity: Not applicable. Viscosity is only relevant for liquids. The substance is a metallic solid with melting point >1500°C, therefore this determination is not required.
• Dynamic viscosity: Not applicable.
• Solubility: Insoluble in water ; 0.015 mg/L (22ºC).
• Water solubility: insoluble in water; 0.015 mg/L (22ºC)
• Metallic iron is rapidly oxidised to form Fe(II), then Fe(II) is slowly oxidised to Fe(III) which finally precipitates to Fe(OH)3 (red iron oxide). Iron does not dissolve in water or dilute aqueous electrolyte solutions, it oxidises with (aerated) water but forms mainly insoluble oxides. A seven-day transformation/dissolution test was performed with iron powder at a mass loading of 100mg/l and a pH of 6.0, according to OECD Guideline 29 and the GHS protocol (Annex 10). Under the conditions of this test, the Fe dilution is 19.4 mg/l for the 7-day endpoint. Chemical equilibrium modelling (ETAP0, 2010) was carried out to calculate a solubility limit for iron using iron(III). Solubility limits of 0.015, and 0.0024 and 0.00001 mg/l were calculated at pH 6.7 and 8, respectively (ECHA).
• Partition coefficient (n-octanol/water) (logarithmic value) : Inorganic substance
• Absolute density: >7.3 g/cm3
• Bulk density: 4,5 g/cm3
• Relative density (water=1; 20ºC): >7.3 g/cm3 (iron: 7.87)

USES

• Use in industrial and professional applications
• Laboratory reagents/analytical use
• Scientific demonstrations
• Display of the magnetic field direction
• School internships