Demonstrations

Diffusion of Bromine

Code Number :	4D50.45
Disclaimer:	Reprinted by permission of Dick Berg, University of Maryland, for use on this website. The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources. Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA. The University of Iowa Disclaimers: University of Iowa Disclaimer All Rights Reserved..
Condition :	Good
Principle :	Kinetic Motion, Distribution of Mass
Area of Study :	Astronomy
Equipment :	Bromine tubes and accessories (2), Vacuum pump, Bromine.
Procedure :	In a well ventilated area (outdoors) put several drops (1 cc) of bromine into the 3 cc syringe. Insert these into the stopcock units as fast as possible without breathing the fumes or spilling the bromine. (The stopcocks should have been thoroughly checked and assembled beforehand. The O-rings in the stopcock units should be heavily greased.) Assemble the rest of the unit as shown. Take care to grease the O-rings and double check the tightness of the unit to avoid leaks. The thick glass tubes should be used for the vacuum tubes. Vacuum should not be applied until the unit is ready to be demonstrated. The speed of the bromine in the evacuated tube should be on the order of 139 m/s. (Speed of Sound in Air) X (Square root of avg. mol. wt. of air = 28 / Square root of avg. mol. wt. of bromine = 160). NOTE: The grease may be easily removed from the glass tubes by using some 'Sparkle' glass cleaner.

References

Hi-4, Hj-9: Freier and Anderson, A Demonstration Handbook for Physics.

Mail Questions and Comments to: Dale Stille