In the Classroom
A Modified Hydrogen/Oxygen Balloon Demonstration I. J. McNaught School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia Abstract Two simple qualitative safeguards are given to reduce the possibility of auditory damage when demonstrating the hydrogen balloon explosion. Keywords Demonstrations Safety/Hazardous Materials Gases Teaching/Learning Aids Supplementary Materials No supplementary material available.
Full Text
Abstract
Return to Table of Contents
Journal of Chemical Education • Vol. 75 No. 1 January 1998 • JChemEd.chem.wisc.edu
In the Classroom
A Modified Hydrogen/Oxygen Balloon Demonstration I. J. McNaught School of Chemistry, The University of Sydney, Sydney, NSW 2006, Australia
Hydrogen/oxygen balloon explosions are very popular and many variations have been described (1). It is usual to warn the presenter to wear ear protection. However the audiences are not so lucky. The sound intensity depends on the ratio of H2 to O2 as well as on the size of the balloon. As noted by Battino et al. (2), it is easy to exceed the hazardous level of 115 dB(A) when using a stoichiometric 2:1 mixture of H2 :O2. We have found that if the ratio 1:2 is used instead and the balloon restricted in size to fit completely inside a 5-L beaker, then the sound intensity remains acceptable. With the given proportions the balloon does not float; this is used as a qualitative indication that the hydrogen pro-
52
portion is acceptable. Because balloons come in different shapes, we find it simplest to restrict the volume by requiring that the balloon fit completely into a 5-L beaker rather than specifying a diameter. Literature Cited 1. Shakhashiri, B. Z. Chemical Demonstrations: A Handbook for Teachers of Chemistry, Vol. 1; University of Wisconsin Press: Madison, 1983; p 106. 2. Battino, R.; Battino, B. S.; Scharlin, P. J. Chem. Educ. 1992, 69, 921–923.
Journal of Chemical Education • Vol. 75 No. 1 January 1998 • JChemEd.chem.wisc.edu
