[neact] More on the whoosh-bottle --

From: carypq <carypq@xxxxxxx>
To: neact@xxxxxxxxxxxxx
Date: Wed, 30 May 2012 14:00:14 -0400 (EDT)


Folks,
   From my previous diatribe I would like to expand on and clarify what I said 
in #3:

   What I meant to say is that the science chair would have sufficient 
science/chemistry/physics content knowledge to be able to evaluate what his/her 
chemistry teachers were doing for demonstrations in terms of safety and 
liability.

    He/she would know whether or not those teachers had sufficient content 
knowledge themselves to be able to evaluate the safety of what they were 
performing in class.

    He/she would know about the maturity level and judgement that his/her 
teachers had and would exercise in selecting appropriate demonstrations and 
performing them safely.

    Actually that brings up three questions I have about this incident that 
would be germane to evaluating it correctly (and probably would not require 71 
pages).

1) Was the teacher acting in a cavalier manner and simply disregarding 
common-sense principle of safety?
    This would entail one kind of address.

2) Was the teacher simply not sufficiently knowledgeable about the chemistry 
involved and experienced with this demonstration?
    This would entail another kind of address.

3) Or was this an anomaly that could have happened to any one of us?
     Thus it would be important for all of us to know exactly what happened so 
we could extend our knowledge and understanding of this chemical/physical 
system.
      We could then:
      a) decide to no longer perform this particular demonstration,
      b) conduct it in some other manner or in some other format or version, or 
      c) address the anomalous issue to prevent this particular event from 
happening to us.

    If you go to the video you'll see 20-liter polycarbonate vessels being 
used. 
    I do it in one-liter soft-drink or gallon soft plastic milk bottles.
    This is a matter of scale.
    
    Did the teacher leave a volume of unevaporated alcohol in the bottom, 
instead of pouring and shaking out the excess?
     If so and it let go, it would throw flaming alcohol onto students.

    Had the polycarbonate bottle been re-used so often that it had developed a 
weakness and let go?
    Note that soft plastic will split, but polycarbonate will disintegrate into 
brittle shards that would fly around and could cut and tear like glass if 
traveling at high speeds.

    Here is another tidbit of information forwarded by Brian Wazlaw from the 
Laboratory Safety Institute:
   http://www.labsafetyinstitute.org/resources/mecannon.htm

   Is THIS the actual event that occurred, done in a physics class? 
   If so, then this is NOT the whoosh-bottle demonstration!

    Let's continue to talk about these issues. 
    In a time of high litigation and a lessening of student interest in 
science, can we afford to throw away demonstration as a valuable pedagogical 
tool?
    Best regards,
    Cary
[neact] More on the whoosh-bottle --

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