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Burning Magnesium

Magnesium is one of the alkaline-earth metals, and is one of the most common elements in the Earth's crust.  In its pure form, it is silvery white, and relatively soft.  It burns in air with a brilliant white light, and for this reason is often used in flares and fireworks.

2Mg(s)  +  O2(g)  ——>  2MgO(s)

The high temperatures reached during the combustion also allow small amounts of magnesium to react with nitrogen in the air, producing magnesium nitride:

3Mg(s)  +  N2(g)  ——>  2Mg3N2(s)

Magnesium also burns in an environment of carbon dioxide such as in a beaker full of dry ice:

2Mg(s)  +  CO2(g)  ——>  2MgO(s)  +  C(s)

Magnesium is used in disposable flash bulbs to generate light for photography, but this use has been largely supplanted by other sources of illumination.

 

In the demonstration below, a strip of magnesium ribbon is ignited with a Bunsen burner:

 

Video Clip:  REAL, 1.41 MB

 

 

!!!  Hazards  !!!

In addition to being extremely bright, burning magnesium produces some ultraviolet light; avoid looking directly at it.

The burning magnesium is very hot; do not touch it or let it come in contact with other flammable materials.

Since magnesium burns in the presence of carbon dioxide, a CO2 fire extinguisher does not put out the flame from burning magnesium; a dry-chemical fire extinguisher must be used instead.

 

 

Procedures

Magnesium in air:  Bassam Z. Shakhashiri, Chemical Demonstrations: A Handbook for Teachers of Chemistry, Volume 1.  Madison: The University of Wisconsin Press, 1983, p. 38-39.

Magnesium in carbon dioxide:  Lee R. Summerlin, Christie L. Borgford, and Julie B. Ealy, Chemical Demonstrations:  A Sourcebook for Teachers, Volume 2, 2nd ed.  Washington, D.C.:  American Chemical Society, 1988, p. 58.

 

 

References

F. Albert Cotton and Geoffrey Wilkinson, Advanced Inorganic Chemistry, 5th ed.  New York:  John Wiley & Sons, 1988, p. 152-153.

John Emsley, The Elements, 3rd ed.  Oxford, Clarendon Press, 1998, p. 120-121.

David L. Heiserman, Exploring Chemical Elements and their Compounds.  New York:  TAB Books, 1992, p. 49-53.

Martha Windholz (ed.), The Merck Index, 10th ed. Rahway: Merck & Co., Inc., 1983.