In the Classroom edited by
JCE DigiDemos: Tested Demonstrations
Ed Vitz Kutztown University Kutztown, PA 19530
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Taming the Barking Dog Ché Royce Seabourne,* George Maxwell, and James Wallace Department of Chemistry, University of York, Heslington, York, YO10 5DD, United Kingdom; *
[email protected] The exothermic reaction that takes place upon the ignition of a mixture of carbon disulfide and nitric oxide has been known for centuries: J. von Liebig, for example, carried out the experiment as a demonstration for the Bavarian royal family in 1853 (1). Today, 150 years later, chemistry students are still enthralled by the bright blue flash and distinctive “woof ” sound produced in the process. Lecturers and teachers may be interested in demonstrating this vibrant and interesting reaction for their students. However, the reaction is known to be dangerous (2, 3). Indeed, during Liebig’s 1853 demonstration, he himself only avoided death thanks to his recreational drug usage (4): The accident [resulting from the ‘Barking Dog’ reaction] would have been fatal for Liebig if his snuff box had not prevented a large splinter of glass from penetrating his femoral artery.
Therefore, having experimented with the reaction ourselves, we have created videos of the reaction in progress that may be useful for teachers of chemistry.W The footage includes film of the reaction, video using a Polaroid filter to enable the flame from the reaction to be seen more clearly, and video showing what happens when carbon disulfide mixing is poor. It is hoped that this footage will allow a wider range of students to see this engaging demonstration, as many teach-
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ers are not prepared to perform the demonstration live (owing to safety concerns). Acknowledgments We would like to thank Richard Douthwaite and the University of York Chemistry Department for Whinfield Project funding. John Holman deserves thanks for his advice and support throughout this project. Finally, none of our experiments would have been possible without the assistance of the laboratory technicians Sue Walton, Dave Lindsey, Zahoor Ul-Haq, and Dave Bettany. W
Supplemental Material
Videos of the demonstration are available in the JCE DigiDemo collection of the JCE Digital Library Web site. Literature Cited 1. University of Leeds Chemistry Department Web site. http:// www.chem.leeds.ac.uk/delights/texts/expt_22.html (accessed Mar 2006). 2. Bodner, G. M. J. Chem. Educ. 1985, 62, 1105–1107. 3. Shakhashiri, B. Z. Chemical Demonstrations; University of Wisconsin Press: Madison, WI, 1986; Vol. 1, p 117. 4. Winderlich, R. J. Chem. Educ. 1950, 27, 672.
Vol. 83 No. 5 May 2006
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Journal of Chemical Education
751
