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woelen
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A very impressive and fairly safe experiment is to use a flash light of a camera for initiating the explosion of a H2/Cl2 mix.
Practical setup:
In a thin glass sphere of 100...200 ml volume, bubble H2 such that it is appr. 50% full.
Next, bubble in Cl2 (do this in a dimly lit room), such that it is totally full. A few drops of water adhering to the glass are no problem.
Stopper the sphere tightly and put the sphere on a table, several meters away from the audience, behind a thick glass pane or perspex pane. The
audience can see the glass bulb filled with H2/Cl2.
Take a big flash unit, connected to a photography slave unit. Put this flash unit behind the glass pane and direct it to the glass sphere with H2/Cl2.
Adjust the flash unit, so that it gives a full blown flash when triggered.
Go to the audience and using a small camera with a real flash unit (not the LED thing of a smart phone) make a picture with flash enabled.
The small flash from the camera triggers the slave unit and this in turn triggers the big flash unit. At the instant of the very bright flash of the
big flash unit, there will be a loud report of the explosion and the glass of the sphere will rattle against the glass pane.
This demo is VERY impressive and you should do it in a dimly lit room. Use candles or small orange/yellow LEDs for lighting to give it the right
ambience and combine with suitable music. You can make a nice little show of this. Most impressive is that you can trigger the explosion from a
distance and especially if you time the explosion with a climax in the music you can get a really nice effect. I once witnessed such a demo when I was
much younger and it really sparked my interest.
IMPORTANT: First try your setup without the audience. It would be very shameful if nothing happens when the flash is triggered. Also important is to
prepare the glass sphere with H2/Cl2 immediately before the experiment. Do not prepare the sphere in advance! Best is to have another person prepare
the bulb while you tell your story. You can prepare the H2 and Cl2 in advance and bring them with you and just bubble these gases into the sphere
under a concentrated table salt solution. Salt solution is better than plain water, because Cl2 dissolves quite well in water, but not so good in
concentrated salt solution.
[Edited on 29-8-16 by woelen]
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NEMO-Chemistry
International Hazard
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Location: UK
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Thanks Woelen, looks like its back on then! I better get some practice in over the next few days!
I appreciate the detailed description, I will have a go first on extremely small scale. I have a couple of those double ended Gas pipette type bulbs
(not sure what they are called), they have a long cylinder type bulb with a tap each end.
I will use those for storing the gas and i have some glass syringes i can use to fill the reaction tubes.
Anyway i will have a play and see what works best. You are correct, i would be horrified if i let my little sister down in the show!
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Morgan
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I recall reading a vivid account of the first chemists discovering this UV initiation using black cloths over flasks and taking them outside to show
the effect.
It brings to mind a building I was in at the university here where they had a lens and mirror tube device on the roof I guess that brought the image
of the sun down and into a dim room whereupon it was projected on the wall, maybe 75 centimeters in diameter. It was really quite something to see the
sun doing its thing live or 8 minute delay I should say. If there was or if there was some way to get enough UV in the image, imagine how succinct it
would be to trigger a hydrogen/chlorine cannon effect as a quartz tube were placed in the roiling imagine of the sun with little solar flares and all.
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NEMO-Chemistry
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Show is tomorrow (Friday), i have had to drop some of the demo's for various reasons and cut the time to 20 mins.
BUT if it goes well then i get another crack at it for longer. I have everything prepared and have someone to assist (head teacher), i have practised
and practised and although fairly basic, everyone i have tested it on has enjoyed it.
No script and its burned into my memory, i have watched so many videos to get an idea of delivery my head is spinning.
I will give details tomorrow of what i did and how it went, i will also start to prepare for the next one (hopefully).
Really looking forward to this and i have a definite theme, the idea is to show that magic can simply be a unknown (from the audience view point)
concept in science.
So it starts out like a magic show (i have some really cool demo's and ways to deliver them), and gradually near the end i show them a couple of
things but instead of saying water i tell them there is a chemical and what it is.
The idea is to show them that science isnt boring or out of reach of anyone prepared to study. For those with zero interest in science, i hope they
simply enjoy what will appear as 'tricks' to them.
To others i hope it sparks the same interest in science i have.
Thanks to everyone for the help. I will post up what i did tomorrow (just in case of last minuet changes). The next one will be longer and more
involved, i am hoping to include the demo's i have had to leave out this time.
I opted to cut a few out as i didnt have them perfected, i would rather not do them than do them and have it fail.
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NEMO-Chemistry
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Done and dusted, details later! Time to grab some lunch and go back to lessons  .
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NEMO-Chemistry
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Ok it went really well, so well i wished i had someone film it. I did think about it but decided it would be a bad idea (especially if i messed it
up).
I will post details of everything i did and what i will do for the next one. I left them with a question and everyone seemed really pleased.
I really enjoyed it. so next time (sometime next month) I get 45 mins which will be tough to do properly.
I made sure i didnt make the normal mistakes like saying Erm every other word (I hate demo video's where they say erm alot). It seemed smooth and
coordinated but having not filmed it i cant look back and see what needs improving!!!
Oh well i will get it filmed next time.
I was ok nerves wise right up until the final 2 mins before it was time to start!!!! I froze behind the curtain solid, but fortunately i had an
entrance planed and as soon as it went off i just went on with the show.
So lesson learned, it definitely pays to practice and practice. thats way even if you freeze just before you start, you go into auto mode as soon as
your start up fires.
Anyway if anyone wants a break down i will do it later, for the next one i need to perfect nitrations, i used it once for the start but didnt go
through with the coloured version this time. My nitrations were not consistent enough but the start one went ok.
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