Zinc is a bluish-white metal used to galvanize iron, and is also found in alloys, batteries, and rubber. Sulfur is a yellow, brittle nonmetal; it can also be found in a powered form. Zinc and sulfur react with each other violently to produce zinc sulfide; the reaction is accompanied by a vigorous evolution of gas, heat, and light:
|Zn(s) + S(s) ——> ZnS(s)||[one of the easier
The products of the reaction also include small amounts of zinc oxide (ZnO) and sulfur dioxide (SO2).
This reaction produces enough hot gas to propel small rockets; this was one of the model rocket propellants described by Homer Hickam in his book Rocket Boys (Delacorte Pr; 1998) [filmed as October Sky (Universal Studios, 1999)].
In the first demonstration below, powdered zinc and sulfur are mixed in a porcelain evaporating dish and heated with a flame; the mixture burns with a yellowish-green flame, and leaves a residue of yellow zinc sulfide in the dish. In the second video clip, a larger sample is ignited in an evaporating dish, which shatters; and in the third clip, a similar mixture cracks a large porcelain crucible.
Video Clip 1: REAL, 3.33 MB
Video Clip 2: REAL, 1.41 MB
Video Clip 3: REAL, 2.62 MB
!!! Hazards !!!
This reaction produces a great deal of heat energy; clear the area of flammable materials.
This reaction must be performed in a fume hood or some open, well-ventilated area. If you do this in a fume hood, be prepared to spend some time wiping zinc sulfide powder off all of the surfaces in the hood.
Bassam Z. Shakhashiri, Chemical Demonstrations: A Handbook for Teachers of Chemistry, Volume 1. Madison: The University of Wisconsin Press, 1983, p. 53-54.
John Emsley, The Elements, 3rd ed. Oxford, Clarendon Press, 1998, p. 120-121, 198-199.
David L. Heiserman, Exploring Chemical Elements and their Compounds. New York: TAB Books, 1992, p. 65-69, 122-124.
Martha Windholz (ed.), The Merck Index, 10th ed. Rahway: Merck & Co., Inc., 1983.