Magnesium sulfide

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Magnesium sulfide
Other names	mag sulfide (jargon) niningerite
Identifiers
CAS number	[12032-36-9]
Properties
Molecular formula	MgS
Molar mass	56.5 g/mol
Density	2680 kg/m3
Melting point	>2000 °C
Solubility in other solvents	decomposes
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Magnesium sulfide is the chemical compound with the formula MgS. It is a colorless crystalline material but often is encountered in an impure form that is brown and non-crystalline powder.

Contents 1 Preparation 2 General properties 3 Applications 4 Safety 5 References

[edit] Preparation

MgS forms by the reaction of sulfur or hydrogen sulfide with magnesium. In the BOS steelmaking process, sulfur must be removed, and is the first element to be. Sulfur is removed from the impure blast furnace iron by the addition of several hundred kilograms of magnesium powder by a lance. The magnesium reduces the sulfur to form magnesium sulfide (MgS). The ionic equations are:

Mg → Mg²⁺ + 2 e^-

S + 2e^- → S^2-[1]

[edit] General properties

MgS crystallizes in the rock salt structure, although the zinc blende structure might be anticipated.^[2] The chemical properties of MgS resemble those of related ionic sulfides such as those of Na, Ba, Ca: 1) MgS reacts readily with oxygen to form the corresponding sulfate, magnesium sulfate. 2) MgS reacts with water to give hydrogen sulfide and magnesium hydroxide.

[edit] Applications

• MgS is a wide band-gap direct semiconductor of interest as a blue-green emitter, a property that has been known since the early 1900's.^[3]
• During the purification of iron, sulfur must be extracted. To achieve this, a "lance" is introduced into the molten metal, and powdered magnesium is poured in. In a violent exothermic reaction ensues, resulting in MgS, which is then raked off as a component of the slag.^[4]
• MgS is claimed to slow labor (childbirth).

[edit] Safety

MgS evolves hydrogen sulfide upon contact with moisture.

[edit] References

1. ^ Chemical storylines, Salters advanced chemistry, heinemann educational publishers, 2000
2. ^ Guntert, O. J.; Faessler, A. "Lattice constants of the alkaline earth sulfides MgS, CaS, SrS, and BaS" Zeitschrift für Kristallographie, Kristallgeometrie, Kristallphysik, Kristallchemie (1956), volume 107, pages 357-61.
3. ^ Tiede, E. "Reindarstellung von Magnesiumsulfid und seine Phosphorescenz. I (Preparation of pure magnesium sulfide and its phosphorescence. I)" Berichte der Deutschen Chemischen Gesellschaft (1916), volume 49, pages 1745-9.
4. ^ Irons, G. A.; Guthrie, R. I. L. "Kinetic aspects of magnesium desulfurization of blast furnace iron" Ironmaking and Steelmaking (1981), volume 8, pp.114-21.