Iron sulphide Iron monosulfide
Dark gray or black, metal-like pieces, plates or rods
4.84 g · cm -3
1195 ° C
Practically insoluble in water
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Iron (II ) sulfide is insoluble in water. With acids, it reacts to form hydrogen sulfide:
On heating to a higher temperature at 138 ° C and 325 ° C. in each case a crystallographic transformation in the solid state. Pure iron (II ) sulfide is light brown crystals of Nickelarsenid type. The technical product is usually colored by residual iron dark to black.
Both in the laboratory and technically can be iron (II ) sulphide prepared by briefly heating a mixture of iron powder and sulfur powder in an exothermic reaction:
In nature there is iron (II ) sulfide as pyrrhotite, troilite and mackinawite.
Bacterial anaerobic corrosion can be seen, which is produced as a final product by the blackening of iron (II ) sulphide. This archaic bacterial metabolism plays in the iron-sulfur world, a scenario for the early evolution of life, an important role.
The green color of egg yolk comes from after prolonged cooking ( more than 10 minutes ) formed - harmless - iron sulfide.
Iron (II ) sulfide was used previously for the synthesis of sulfuric acid. In this case, the iron (II ) sulfide was roasted under the supply of air, the sulfur dioxide needed for the further synthesis was formed. In the laboratory can iron (II ) sulfide are used for producing hydrogen sulfide.