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Tue, October 25, 2016,08:28

Chemical Reactions

Elemental sulfur undergoes a number of reactions. Sulfur reacts with oxygen to produce sulfur dioxide, with fluorine to form sulfur hexafluoride, with chlorine to produce sulfur dichloride and disulfur dichloride, with metals such as zinc and magnesium to form sulfides, and with hydrogen to form hydrogen sulfide(see Chemical compounds):

Reaction of sulfur with air

Sulphur burns in air to form the gaseous dioxide sulphur(IV) oxide, SO2.

S8(s) + 8O2(g) → 8SO2(g)

Burning Sulfur. Sulfur burns in air with a blue flame and produces sulfur dioxode. In this photo, a sample of burning sulfur has been lowered into a bottle of pure oxygen gas

Reaction of sulfur with water

Sulphur does not react with water under normal conditions.

Reaction of sulfur with the halogens

Sulphur racts with all the halogens upon heating.

Sulphur reacts with fluorine, F2, and burns to form the hexafluoride sulphur(VI) fluoride.

S8(s) + 24F2(g) → 8SF6(l) [orange]

Molten sulphur reacts with chlorine to form disulphur dichloride, S2Cl2. This apparently smells dreadfully. With excess chlorine and in the presence of a catalyst, such as FeCl3, Snl4, etc., it is possible to make a mixture containing an equilibrium mixture of red sulphur(II) chloride, SCl2, and disulphur dichloride, S2Cl2

S8 + 4Cl2 → 4S2Cl2(l) [orange]

S2Cl2(l) + Cl2 ⇌ 2SCl2(l) [dark red]

Reaction of sulfur with acids

Sulphur does not react with dilute non-oxidizing acids.

Reaction of sulfur with bases

Sulphur reacts with hot aqueous potassium hydroxide, KOH, to form sulphide and thiosulphate species.

S8(s) + 6KOH(aq) → 2K2S3 + K2S2O3 + 3H2O(l)

Reaction of sulfur with Metals

Iron(II) sulfide and zinc sulfide are quite stable compounds and their formation from the metal and sulfur is highly exothermic. However, iron and sulfur and zinc and sulfur can be mixed at room temperature and no reaction takes place. Only when heated to the temperature of a red-hot metal rod do they react rapidly-in the case of zinc, almost explosively.

Equations for the principal reaction in each case are

8 Fe(s ) + S8(s ) __> 8 FeS(s )

8 Zn(s ) + S8(s ) __> 8 ZnS(s )

In addition to ZnS(s ) some ZnO(s ) and some SO2(g ) are produced by the high temperature of the second reaction.


Play movie (QuickTime 3.0 Sorenson, duration 19 seconds, size 1.3 MB)

Zinc powder and sulfur are mixed. A heated metal rod causes the mixture to react vigorously. Here is another view of the reaction.

 A mixture of powdered zinc and sulfur will vigorously react when ignited to produce the ionic compound zinc sulfide. Mixtures of zinc and sulfur have been used as rocket fuel. Some additional photos of this reaction can be found on the reactions page.


Play movie (QuickTime 3.0 Sorenson, duration 32 seconds, size 2.2 MB)

Iron powder and sulfur are mixed. A heated metal rod initiates an exothermic reaction. The reaction product, iron sulfide, is fused to the rod.

Iron powder and sulfur are mixed.

A metal rod is heated.

The heat initiates an exothermic reaction.

Iron sulfide is fused to the rod.



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