Zinc and Sulfur

In this reaction a mixture of powdered zinc and sulfur are ignited with a bunsen burner. This an oxidation-reduction reaction, where a compound (in this case zinc sulfide) is produced from the constituent elements (zinc and sulfur).

A mixture of zinc and sulfur is heated with a bunsen burner An initial flare-up
Reaction begins in earnest The blue-green color of the flame is due to the exicitation of zinc ions
Almost done; one final flare-up The end result - a hot glowing mass of zinc sulfide

Notes: For this reaction to occur the zinc must be fresh. In this reaction we employed zinc power that was first washed with dilute hydrochloric acid. Also, the reactants must be thoroughly mixed; here they were first ground in a mortar and pestle. The reaction can sometimes be hard to start; you may see a blue flame resulting from the combustion of the sulfur.

Hazards: Reactions such as this should only be performed by porfessional chemists. This reaction produces a lot of heat and can occur rapidly if the zinc and sulfir are htoroughly mixed. The reaction has been known to blow apart glassware - even a mortar!

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