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Author: Subject: school chemistry demo out-of-control
Magpie
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school chemistry demo out-of-control

I'm not sure what the teacher was trying to show here but it looks like it nearly was disasterous. But notice how the naive students enjoyed it.

The single most important condition for a successful synthesis is good mixing - Nicodem
#maverick#
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wow what fucking moron, but then again he probably didnt think that one through, i agree with a comment everyone should have had atleast eye protection
Mister Junk Pile
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I always find it interesting to think about what's happening to the video in these situations. Notice how, shortly after you see the flash in the hood, the screen turns blue. I'm not an expert in this type of thing, but what caused that? Did the camera "over-adjust"? Is it a compression artifact? Was the camera physically distorted by the shockwave?

I've been curious about this ever since I saw a "home video" of a nuclear test (a small atmospheric test in Nevado; can't remember the exact name; maybe Plumbob or Teapot). It was one of the "soldiers" taking a video with his own camera and as soon as the flash occurs you hear this constant fluctuation in the audio. I wish I could find it to show but it's not on the internet anywhere. It's on the DVD: The Atomic Bomb Movie and it's one of the special features. I realize this is EM interference, but of what type and what is the mechanism inside the camera?
watson.fawkes
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 Quote: Originally posted by Mister Junk Pile I realize this is EM interference, but of what type and what is the mechanism inside the camera?
The mechanism is electromagnetic induction. Nukes make large amounts of ionizing radiation, that leads to, wait for it, large amounts of ions, that is, plasma. Plasmas emit all sorts of EM radiation, and ones from nukes emit lots of it. The conductors inside the camera act like tiny antennas and transformer secondaries, picking up energy from the field. These conductors always do this, but ordinarily the amplitudes are small enough to be ignored. The EM pulse from a nuke, though, doesn't generate ordinary amplitudes.
Jor
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Yes I have seen this movie this before.
This teacher is obviously either very stupid or wasn't paying attention. When you do such a reaction you do it outside or in the open, not in an almost closed chamber such as a fume hood. He should have never pulled the sash down. The pressure had nowhere to go and thus shattered the sash. Would he not have lowered the sash nothing would have happened.
And acetylene is not toxic anyway (well maybe the phosphine impurities are but these are very minor impurities) so he shouldve just done it on the lab bench.
mr.crow
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Some some safety idiot told him he had to do all experiments in the hood. Guess what, it became less safe

Double, double toil and trouble; Fire burn, and caldron bubble
The WiZard is In
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 Quote: Originally posted by Mister Junk Pile I've been curious about this ever since I saw a "home video" of a nuclear test (a small atmospheric test in Nevado; can't remember the exact name; maybe Plumbob or Teapot). It was one of the "soldiers" taking a video with his own camera and as soon as the flash occurs you hear this constant fluctuation in the audio. I wish I could find it to show but it's not on the internet anywhere. It's on the DVD: The Atomic Bomb Movie and it's one of the special features. I realize this is EM interference, but of what type and what is the mechanism inside the camera?

The International Pyrotechnics Society Newsletter — December 1988

Dr. Roger Louis Schneider of Rho Sigma Associates, Whitefish Bay, Wisconsin, U.S.A.,
was recently involved in preparing a segment for the U.S. television program "Newton's
Apple". He prepared the following paragraph for inclusion in our Newsletter, which of
course we are extremely proud to do.

"NEWTON'S APPLE" is a weekly syndicated half-hour television program which is
out the U.S. Program number 608 available for broadcast by local PBS stations during
the week of November 27th, had as its main feature a segment on FIREWORKS. The
guest expert for the segment was Dr. Roger Schneider, one of our IPS members.
TheNEWTON'S APPLE program, which is produced by KTCA-TV, St. Paul, MN,
attempts to bring science to the general public,, using sometimes very elaborate stage
props and demonstration equipment to help explain scientific principles. The producer
of the FIREWORKS segment was familiar with Bartolotta's Fireworks Co., Genesee
Depot, WI, and their very popular July 3rd Milwaukee Lakefront Fireworks Display.
During the early planning of the segment, she contacted the Bartolotta firm and inquired
about the availability of a fireworks expert. Dr. Schneider, a consultant to the
Bartolottas', was strongly recommended for the job, not only because of his knowledge
of pyrotechnics, but also because he has done many science lecture-demonstrations
for general audiences. Dr. Schneider had prepared about an hour's worth of
demonstrations for the segment, with the understanding that for one technical reason or
another, or simply because of time constraints, most would not be seen in the final
version of the segment. Dr. Schneider pointed out that some of the demonstrations
which would be real crowd pleasers in the lecture hall, were inappropriate for the
television studio. One very interesting thing occurred during the filming of the in-studio
portion of the segment. During the burning of a particular star mixture, the
transmissions from the wireless microphones worn by Dr. Schneider and the program's
host were jammed. Dr. Schneider suggested we may have the makings of a
pyrotechnic electronic counter measure!

------------------
The International Pyrotechnics Society Newsletter — June 1989

You will recall that the last issue of our Newsletter featured a tribute to Dr. Roger Louis
Schneider for his being retained as a consultant for the television show "Newton's
Apple". Reference was made to the possibility of a pyrotechnic electronic
countermeasure. However, Mr. Donald J. Haarmann, aka The WiZard is In Correspondent
for American Fireworks News, has
informed us that it has already been patented. He references R.
P. Cornia and R. R. Reed, Jr., Thiokol Corporation, 1976, U.S. Patent No. 3,983,816,
"Compositions for Producing Flickering Signals"; to quote: "The compositions burn to
produce flickering signals of' flame and smoke, and which emit infrared and radar
signals". The radar emissions are attributed to the use of a cesium (nitrate) in the
compositions. However, he also points out that compositions using cesium (nitrate)
were also developed by H. C. Clauser and R. S. Longs (Kilgore Company, 1953, U.S.
Patent No. 2,651,567), but that these inventors make no mention of this phenomenon.
Mr. Haarmann concludes that perhaps they were not looking for radar emissions.

djh
----
“As a scientist, I cannot understand how a competent chemist can
select any --------- for demonstration purposes or other purposes
without clear knowledge of the nature of these materials and the
anger involved with their use. Have we stopped short of scientific
aturity so that we indiscriminately use or select for use chemicals,
or example, without investigating the reality of their
characteristics? The toxic chemical problems of today strongly
suggest that we have.”

Extracted from:

EJ Schwoegler’s letter in: C&EN January 7, 1985. Written in
response to W Hutton and S Heideman’s letter in C&EN
September,1984.

-----------
The way to capture a student's attention
is with a demonstration where there is
a possibility the teacher may die.

Jearl Walker, Cleveland State University

Mister Junk Pile
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Watson, I am aware of EM induction but thank you for the explanation. What I meant was the precise mechanism of what the induction does inside the camera to cause it to be pulse-like in nature. You would expect a sudden increase in EM radiation at detonation and then exponential decay of the "amplitude" (number of photons) over a period of a few seconds but not a regular pulse. Wait it must be induced by mechanical motion of the film being "rolled"! That is the only explanation I can think of.

However, I find what the camera does during the conventional explosion intriguing because it is less likely to be explained using photons.
The WiZard is In
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 Quote: Originally posted by Mister Junk Pile I always find it interesting to think about what's happening to the video in these situations. Notice how, shortly after you see the flash in the hood, the screen turns blue. I'm not an expert in this type of thing, but what caused that? Did the camera "over-adjust"? Is it a compression artifact? Was the camera physically distorted by the shockwave?

This is typical for inexpensive Video cameras. Ever see a firework
display video'd with an amateur camera? The cameras sensor
cannot handle the sudden changes in light levels/hue. The ones they
us on the News (Big \$) do a good job.
Mister Junk Pile
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watson.fawkes
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 Quote: Originally posted by Mister Junk Pile Watson, I am aware of EM induction but thank you for the explanation. What I meant was the precise mechanism of what the induction does inside the camera to cause it to be pulse-like in nature. You would expect a sudden increase in EM radiation at detonation and then exponential decay of the "amplitude" (number of photons) over a period of a few seconds but not a regular pulse. Wait it must be induced by mechanical motion of the film being "rolled"! That is the only explanation I can think of. However, I find what the camera does during the conventional explosion intriguing because it is less likely to be explained using photons.
My guess is that there's a difference in physical effect between the video wipe-out and audio distortion. I was addressing the audio effect. The video one is indeed just of saturation and rate of change.

 Sciencemadness Discussion Board » Fundamentals » Miscellaneous » school chemistry demo out-of-control Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues