Fusionfire
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Reaction rate demonstration for school children
At an upcoming party, I've been thinking about a safe but memorable experiment to conduct for school children that demonstrates the importance of
surface area when it comes to reaction rates. The traditional calcium carbonate chips with dilute acid is quite boring 
Two that I've come up with are:
1) Zinc + sulphur. Nice green smoky flames. I can probably buy a large bag of sulphur crystals, hopefully with a variation of crystal sizes I can sort
into different piles. Otherwise I can melt, cast and break up my own crystals.
2) Potassium nitrate + sugar. I can easily buy sugar crystals of different sizes (rock sugar, granular sugar, caster sugar) and mix these with
potassium nitrate.
Obviously all these experiments will be done outside on a flat plate with no confinement. Can you guys think of any others?
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#maverick#
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Potassium chlorate + powdered sugar and a few drops of Conc. Sulfuric acid
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peach
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If you have iodine, AlI3 can demonstrate it; aluminium into a solution of iodine.
In none polar solvents, it takes absolutely ages and is boring.
In ethanol, it can move quite a lot more rapidly. When using ethanol myself at one point, I decided to use micronic aluminium to get it done. It's all
combined in the flask and given a gentle warm it get it going.
With the micronic powder in there, once it started, it really shifted! Within thirty seconds, with me having lifted it off the mantle, it was
continually accelerating and running away. I could see the ethanol vapour coming out the neck as it hit it's boiling point and the contents began to
foam up with all the vigorous boiling going on. They then volcanoed themselves out and onto my hand, giving me the most awesome iodine stain I've ever
had.
But that's essentially the good old baking soda and vinegar volcano, just a different colour of it. You could demonstrate the same principle by using
big lumps of baking soda and then fine powder, with food dye added.
It depends which age range of kids you're addressing. If they're in there teens, you may be able to go on with the iodine example to mention the fact
that it's own heat is causing it to accelerate, and that it will keep doing so until it reaches the boiling point of the solvent and that this
property is important when building chemical plants to avoid them melting down. Again, depending on their age, there are points you can pick up on
about aluminium and the iodine as well; like that the latter is so immensely important for surgeons when washing their hands.
I was running that reaction in a half filled 50ml or 100ml flask I think, and ended up doing it again but in a 250ml flask and with a bowl of ice
beside the mantle.
Attempt one, obviously need a much bigger flask for this
Some washing later, I have my hand back
Not exactly 'overfilled'
It tried getting out of this one too though
The free iodine is gone by the end
Here's a picture of 'T2 Laboratories', where something similar occurred on a much larger scale. They were qualified as undergraduates and were making
a petrol additive that involved heating the mixture with molten sodium, under pressure. They tested it at 1l, then went to a 10,000 litre reactor. The
reaction was exothermic. Once started by warming, it would drive it's self forward. Something failed on the cooling jacket, which had no backup,
allowing the contents to go into a completely unstoppable runaway state. When the casing failed (full of pressurised hydrogen, molten sodium and
whatever their additives were), the reactor blew windows and fronts out of trailers and shops in the town, and annihilated the plant, and four members
of staff.
I love the way the business owner says window.
<iframe sandbox width="640" height="510" src="http://www.youtube.com/embed/C561PCq5E1g" frameborder="0" allowfullscreen></iframe>
[Edited on 17-7-2011 by peach]
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UnintentionalChaos
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Put a teeny spatula of luminol into some DMSO in the pestle of a mortar and pestle. It dissolves. Add some NaOH or KOH chips/prills. There is a faint
flow seen around the pieces of hydroxide. The base-induced oxidation of luminol by dissolved oxygen occurs on the surface of the solid hydroxide. Take
the mortar and grind the chips of base to a powder under the DMSO. Suddenly, the liquid lights up as you have increased the surface area massively. To
see it in action, go to my video and fast forward to 24:30
I think that reflection of light off the white porcelain of the mortar and pestle is a significant contributor to the perceived brightness and it may
not be as impressive in other colors or a clear glass mortar
http://youtu.be/-PGtoZEZnzc
[Edited on 7-17-11 by UnintentionalChaos]
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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Fusionfire
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Thanks for the suggestions folks. The children are between 7 - 11 years old.
To Peach:
Nice pictures . Reminds me of hand henna painting.
CSB video. What muppets, the chemical plant owners. With a reactor vessel like that, with some common sense they should have buried it in the ground,
in a pit in the ground or at ground level surrounded by earth buttresses, at the very least. The way the vessel was placed above ground level
basically maximised its effect as an airburst explosive for destroying soft targets (nearby civilian buildings + people)
[Edited on 18-7-2011 by Fusionfire]
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Fusionfire
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Oh yeah. I was going to take one large bowl of sweets and tell the children they all have to rush to get one sweet, and time them.
Then I was going to scatter the sweets over the garden and tell everyone to pick up one sweet, and time them.
That ought to do for audience participation, then I'd proceed to the fiery bits 
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peach
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7-11 may be a bit young for some of that then. 
Being from the UK, I don't know whether freshmen and sophomores are the kids in school or adults pretending to be teens in pornos.
The CSB thing, never mind the 10,000l reactor, they should have at least tried a 100 or 1,000l somewhere in between. Jumping 4 orders of magnitude in
one go was the first major error.
I've watched most of the CSB videos. Some of them involve large numbers of people dying. In a morbidly amusing twist of fate, they have one up about
DuPont. They were using multiple 1 ton tanks of phosgene to produce insecticides. One of the hoses on a tank popped. Only one member of staff died.
Far less than the quantity who have died in their videos about combustible dust explosions. An evil, toxic weapon of war, stored and used in mass by
the company, far out numbered in it's mortality rate by dust sat on the girders of buildings.
[Edited on 18-7-2011 by peach]
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sternman318
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As far as peach's suggestion goes- you can also do this dry. Adding finely powdered magnesium to dry crystals of iodine makes a nice little purple
smoke signal. If it doesn't go off at first, a drop of water will get it going. Here is a video. My magnesium was probably less fine, and i remember it reacting more slowly than that of in the video, so you could try it with
two different sized magnesium ( or aluminum) powders.
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MrHomeScientist
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Another thing you could try is different particle sizes in thermite. The smaller the particle size (larger mesh number), the faster the reaction will
go. Intimite mixing is also key. I've had experience with this using 80 mesh and 400 mesh Al powder, the latter proceeding much faster (and it was in
fact the only way I got my Cr2O3 thermite to work at all!). You probably want to stick with the standard red iron oxide composition, as it will be the
cheapest and isn't as explosively violent as some of the others I've done.
Thermite would certainly make an exciting demonstration, just make sure the kids stay far enough away!
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peach
Bon Vivant
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Thermite is good in terms of it being exciting, but I'm not sure how appropriate it is given that aluminium is now gone from eBay as a result of how
well abused the powder is. There's a significant burn risk from that when combined with 7 year olds (it spits quite a long distance if it touches
anything damp).
It'd be nice to see someone actually cast something from the iron; like the school emblem, which would be fitting with the arts theme. <---- if you
do this, photos are mandatory.
[Edited on 19-7-2011 by peach]
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Fusionfire
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Aluminum powder can still be found in a few specialty shops in the UK. PM me if you need help.
That said the only way to truly be self-sufficient of all these chemophobes stopping sales in the name of pre-crime is to be able to make your own
aluminum powder from various forms - scrap, rods, sheets, tubes, etc. Aluminum is too ubiquitous a metal for the padded room brigade to ban
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