Jay Maity - 21-8-2004 at 17:26
Can anyone tell me some interesting reactions, which can be viewable to public.
It must not be so much costly.
Edit: Title made more legible. Chemoleo
[Edited on 22-8-2004 by chemoleo]
Hang-Man - 21-8-2004 at 18:24
I’ve got a great one. First you isolate fluorine (piece of cake, google it) then you buy about 200 grams of francium metal, (ask at the pharmacy,
they will order it for you). Then you just drop the chunk of francium into the flask with the fluorine gas. It’s a real show stopper.
BromicAcid - 21-8-2004 at 18:35
So you're looking for a demonstration basically:
Putting a few drops of mercury on a large block of aluminum and exposing it to the atmosphere supposedly will turn the whole mass to powder in a
somewhat short time, always thought that sounded interesting.
Spontaneous combustion of white phosphorus would be a neat but obtaining the phosphorus, although cheap if you have a legal source, is quite
difficult.
The oscillating iodine clock reaction is a classic demo, more information can be found, but it calls for somewhat more exotic reagents.
Burning a magnesium strip is a good way to get attention, pass out sun glasses beforehand.
Thermite reactions, reacting sodium with water, reaction of sulfur with iron filings, burning alcohol mixed with barium/strontium/lithium salts.
I've seen many many demos and there are literally as many as people can think of. There is a book floating around somewhere named "Classic
Chemistry Demonstrations: One Hundred Tried and Tested Experiments" that looks like it would be quite interesting.
More chemistry demos
JohnWW - 21-8-2004 at 20:11
The longest-lived isotopes of francium have half-lives of only 19 and 21 minutes! Francium (atomic number 87) is, in fact, the least stable element
with atomic number below about 100.
John W.
chemoleo - 21-8-2004 at 20:12
JohnWW - just in case u haven't figured - he was taking the piss.
You are turning into a walking dictionary! 
The_Davster - 21-8-2004 at 20:35
There is also sugar in conc. sulfuric acid, ammonia fountain, and NI3.
I have a book around here somewhere called "chemical magic" that has a lot of demonstration type chemical reactions. If I can find it I can
contribute a lot more ideas.
Blind Angel - 21-8-2004 at 21:49
Why not the Mercury heart, put a drop of mercury into a saline solution (google for the precise one) and touch it with a needle, it'll beat like
a heart.
guy - 21-8-2004 at 22:12
There's always pyrotechnic experiments like KMnO4 + glycerine (brake fluid works well too)
JustMe - 22-8-2004 at 11:05
Not so cheap (but not bad)... you'll need some silver nitrate, distilled water and a copper strip. Dissolve the silver nitrate in the distilled
water (it doesn't need to be concentrated), and shape the copper strip into an ever widening spiral. Drop into the solution. Immediately the
copper displaces the silver, and over a period of hours you'll get what looks like a silvery christmas tree with silver stalactites hanging off
of the copper.
Cheap and impressive (not in a pyrotechnic way): Create Instant Rust® 
Mix equal amounts of normal chlorine bleach and vinegar (oh, say about 6 ounces or so of each), and add steel wool. It crumbles to rust in seconds.
neutrino - 22-8-2004 at 12:40
I'd suggest playing with acids and bases in indicator solutions. Take your indicator (universal indicator or homemade red cabbage should do
nicely) and add it to a big beaker of water that is being stirred w/a magnetic stirrer. Add some Mg(OH)<sub>2</sub>. Add a small amount of
acid and it will go acidic for a second, then go back to basic (this is due to the limited solubility of Mg<sub>2</sub>
. Add more acid until it becomes acidic and note how it goes clear at this point.
DDTea - 23-8-2004 at 09:14
My General Chemistry teacher loved to do little demonstrations, especially on the first day of school to boggle our little minds...usually, they
involved phenolthalien (I hope I spelled that properly).
In one case, she wrote "Welcome to Chemistry!" on a few pieces of coffee filter (one filter per letter) with phenolthalien. Then as the
class came in and took seats, before she said anything, she sprayed each coffee filter with the Windex and turned the phenolthalien letters a deep red
for all to see .
She did a spoof on a titration in another demonstration, claiming to turn "water into wine!" The poor students were so boggled that one
asked, "Can you drink it???" Well as the case may be, perhaps you could--if you felt like evacuating your bowels 
.
I miss that chemistry teacher 
I am a fish - 23-8-2004 at 10:24
Some of my favourite reactions involve creating extremely intensely coloured compounds from colourless or weakly coloured reagents.
Examples include:
Copper(II) Sulphate + Ethylene Diamine (Deep Purple)
Iron(III) Chloride + Sodium Thiocyanate (Blood Red)
Iron(II) Sulphate + Potassium Ferricyanide (Navy Blue)
Benzenediazonium Chloride + Phenol (Bright Yellow)
Armstrong's Mixture
MadHatter - 24-8-2004 at 08:24
My chemistry teacher demonstrated the dangers of mixing certain
compounds together and whacking them with a hammer. KClO3 and red P
in this case on an anvil. Unfortunately, I blew my eyebrows off later
with this same mixture(stole it from the Chem Lab). Never mixed those
2 together again !
DDTea - 24-8-2004 at 15:45
MadHatter just reminded me of a lab I did with the same chemistry teacher I mentioned earlier...
Basically, we prepared Hydrogen and Oxygen gases in separate syringes (not difficult to do). We then attached tubing to the syringes, with the
other end of each tube in some dish detergent in a syringe. We then made a bubble of a Hydrogen/Oxygen 2/1 mixture, and lit the bubble with a match.
Needless to say, we got a loud "POP" and some of the petri dishes broke while others were thrown across the classroom. Crazy teacher she
was
On another note, I remember waaaayyy back in like third grade or so, some chemists came in to entertain us with some demonstration experiments. The
one I remember most was where they took a bunch of those monkeys-in-a-barrel (you know, the little red plastic monkeys whose arms are shaped such that
they can be linked together and form chains?) and put them in their barrel...then shook the little barrel up and pulled them out--all linked in one
long chain. I have no idea how that was done, and it boggled our little audience.
[Edited on 8-24-04 by Samosa]
The Fun Days !
MadHatter - 24-8-2004 at 20:14
MrSamosa, I too remember the fun days of chemistry in school.
I'm prettty sure that some of my instructors were as crazy if
not crazier than I am ! I LOVED THEM ! That was my kind
of instructor - not worried about a punk's parents' lawsuit because
his/her hands got stained with a common dye used in biology !
And in the early to mid 70's - not afraid to demonstrate an explosive !
Some of today's teachers are pussies in contrast !
To the good old days: MUHAHAHAHAHAHA!
[Edited on 25-8-2004 by MadHatter]
true_alchemy - 4-10-2004 at 17:56
I got a couple of neat ones. The deep yellow lead iodide precipitate is quite awesome. (PbNO3 in water + Na or KI in water
small peices of calcium carbide added to HCl and bleach ignites spontaneously. (I did that as a cub scout- starting a fire without matches-hehe)
The flame color of LiCl is breathtaking!
tom haggen - 4-10-2004 at 23:00
Alkali metals and H2O react quite nicely. Also, you might try mixing NaOH with nitromethane. Good luck
Andy B - 18-10-2004 at 08:01
try hydrogen peroxide decomposition, use potassium iodide as a catalyst and have some fairy liquid to form bubbles.
Have a bottle/bowl full of H2O2 and have a layer of detergent on top.. add the catalyst and hey presto: Orange-y brown-y foam!
froot - 18-10-2004 at 12:21
Aaah those good old days.
Our science teacher decided it was time to dispose of a whole jar of old suspect looking potassium metal in kerosine. She dragged us up to the
school's swimming pool and gave everyone a turn to fling a large block of K into the pool with forceps. Those explosions still haunt me.
The pool was a little off colour for the next week leaving the caretaker a little bewildered .
Another neat trick she did was melting KCLO3 in a testube and dropped in a splinter of wood which immediately incinerated itself.
[Edited on 18-10-2004 by froot]
neutrino - 18-10-2004 at 14:49
Add styrofoam packing peanuts to 30% H<sub>2</sub>O<sub>2</sub>. The styrofoam is destroyed as soon as it hits the peroxide.
precipitation reactions look pretty neat.
Hermes_Trismegistus - 18-10-2004 at 17:35
Like KI (aq) and Pb(NO3)2....two clear solutions that turn bright yellow and opaque when mixed. It's also cheap like borscht.
Adding a strip of copper metal to nitric acid is pretty neat too, clear acid...copper metal....to green liquid and red fumes (need some ventilation
though)