Iron(II) sulfide

Iron(II) sulfide is a chemical compound with the formula FeS. In practice, iron sulfides are often non-stoichiometric. Powdered iron sulfide is pyrophoric.

FeS can be obtained by reacting iron and sulfur.

S_{8 (s)} + 8Fe_(s) → 8FeS_(s)

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Forms of iron sulfide

"Iron sulfide" exists in several distinct forms which differ in the stoichiometry and properties:

• Pyrrhotite, Fe_1-xS, a mineral as well as the waste product of the Desulfovibrio bacteria, pyrrhotite displays ferrimagnetism.
• Troilite, FeS, which has similar material to pyrrhotite, but does not possess ferromagnetic properties.
• Mackinawite, Fe_1+xS, the least stable from of iron sulfide, mackinawite has a layered structure.
• Pyrite, mineral form of FeS₂ with a gold-like appearance, making it also known as "fool's gold."

Pedagogical uses

Certain chemical principles are nicely illustrated using the chemistry of iron sulfides. The methods of chemical composition can be shown by the production of iron(II) sulfide from iron and sulfur (see equation above).

• This reaction is exothermic as more energy is given out than taken in.
• Iron shows ferromagnetism; iron sulfides do not.
• Iron sulfide with hydrochloric acid (HCl), the acidic properties of hydrochloric acid and the pungent fume of hydrogen sulfide can both be demonstrated:

FeS_(s) + 2HCl_(aq) → FeCl_{2 (aq)} + H₂S_(g)

See also

• Iron-sulfur world theory

References

• D. Vaughan, J. Craig, (1978) Mineral Chemistry of Metal Sulfides, Cambridge University Press. ISBN 0-521-21489-0