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Jor
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[*] posted on 14-2-2009 at 14:25
experiments for my brother


Today me and my 16year old brother had a good idea. He wanted to perform an experiment by himself.
I made 3 experiments, in wich I assist him, and carefully supervise, but he does all the actions himself.
-Adding ammonia to copper sulfate solution
-Adding a 40% HBr solution to copper sulfate solution
-Adding some conc. nitric acid to iron fillings and heating (brown gas: NO2).
All the experiments are performed in my good working home made fume hood. Running water is nearby (about 0,5meter) in case he spilled a corrosive.

Do you guys have any suggestions of experiments, wich might be really exciting/interesting for him?
It should not:
-take too long (15min max)
-involves chemicals not suitable for him (like poisons, very corrosive materials, cumulative hazards, etc.)
-Small scale

I think it is a good thing to let him handle a thing like conc. nitric. he is smart and no k3wl, and I told him exactly what to do and not do. Now he knows, that if handled properly, these chemicals are not instant death like the media likes us to believe.
It is important to give him a good first image however. If you do outside hood, inside, and he gets a wiff, he will never touch the stuff again ;)

Have you guys done this? Give a experimental procedure to someone, and let him/her carry out?
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panziandi
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[*] posted on 14-2-2009 at 14:39


Perhaps thermal decomp of a polymer and collecting the vapours? You can make methyl methacrylate from perspex chips and then repolymerise the product.

You could react magnesium metal with steam in a test tube.

You could try reacting iron wool with Br2 vapours and with I2 vapours in test tubes.

Crack an alkane in a test tube over broken china to make alkenes which you could react with KMnO4 solution and with Br2 solution.

a few ideas there...




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smuv
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[*] posted on 14-2-2009 at 15:38


I used to do simple experiments with a (now) ex-girlfriend. We both enjoyed each of the experiments listed below.

We bleached a red skinned potato with SO2 (just take a potato peel, put it in a container and fill the container with SO2 gas, check on it every once and a while to monitor the progress).

Made black powder...

Made ethylene by cracking naptha, and blew up balloons of it :cool:

Made ethyl nitrite and combusted it (nice grey flame, very cool).

Combusted ethyl chloride (blue flame)

" " solutions of boric acid in ethanol

Mixed TCCA and acetone; demonstrated that the mixture was stable; then let her add a drop of sulfuric acid, allowing a vigorous exotherm to occur.

In my experience (remember this is catering to girls) make sure the experiment is fast and already set-up, because they really don't care about how it occurs, more what occurs. Experiments with fire and color changes are most interesting. If he/she is a klutz be careful with expensive glassware...learned that the hard way. Never do an experiment in a rush. Always make sure that the other person genuinely wants to do the experiment.

[Edited on 2-14-2009 by smuv]




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[*] posted on 14-2-2009 at 15:59


Make hydrogen ballons by reacting HCL and alumnum foil. You can set them on fire, or use them as weather ballons.

Akali metals. You could even make an alloy with potassium and sodium and show him how it reacts more than just potassium or sodium alone.

KMn04 and Glycerin.

Potassium Chlorate reacting with sugar.

Osmosis of an iodine solution in water with a tube of some sorts filled with a starch solution.

Lots of stuff out there...
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[*] posted on 14-2-2009 at 19:31


Jor, glad to see that you are taking such good care of your little brother. ;)

Here's some test tube reactions that I find interesting:

1. Add a drop of FeCl3 solution to a ml of water. Add a small crystal of NH4SCN and stir. Note the blood red color. Add a few drops of NaF solution. It should completely clear up. My understanding is that the[FeF6]-3 complex is much stronger than the [Fe(SCN)6]-3 complex.

2. Place a few drops of a sulfide solution in a small test tube. Add several drops of conc. HNO3. The solution should cloud up with a colloidal suspension of elemental sulfur.

S-- + 2HNO3 + 2H+ ----> S + 2NO2 + 2H2O (I think)

3. Dissolve a small crystal of K4Fe(CN)6 in a ml of water. Add a drop of FeCl3 solution. A colloidal suspension of Prussian blue should form.

----> KFeFe(CN)6 containing both Fe(II) and Fe (III)

4. To a ml of dilute CuSO4 add dilute NH4OH dropwise until a pale blue precipitate of Cu(OH)2 forms. Then add some more NH4OH until the ppt clears and you are left with a dark blue translucent ammonia complex of Cu(II).

[Edited on 14-2-2009 by Magpie]
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[*] posted on 15-2-2009 at 00:31


Some more spectacular things, which your brother also safely can do.

1) Add a pinch of red phosphorus to gaseous Cl2 (you make the Cl2 in a test tube, he adds the red P).
2) Make a mix of KNO3, red P and some Al-powder (if you don't have Al-powder, then you can use Mg-powder instead) and let him throw such a mix in chlorine gas.

Use very small quantities of red P and other chemicals (just 10 mm3 or so).


If you have sodium thiosulfate, then you can make an artificial sunset. Dissolve 1 gram of Na2S2O3 in 500 ml of water and put this in a glass jar. Next, add 10 ml of 10% HCl and stir. Let this solution stand and watch it go cloudy, very slowly. If you look at a white lamp through the solution, it will turn from white to yellow through shades of orange and finally it fades.

Also nice to see is reversible change of color with temperature. Dissolve some CoCl2.6H2O (or CoSO4.7H2O) in 10..15% HCl. The solution is pink. Heat the solution to almost boiling. The solution becomes blue. On cooling down it becomes pink again. It is best that you fiddle around a little bit with the concentration of acid (do this alone, not when your brother is there). The exact concentration of acid must be chosen well. Too low a concentration, and your solution does not turn blue on heating, too high a concentration, and the solution becomes blue immediately, or does not turn pink again on cooling (due to loss of water vapor).




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not_important
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[*] posted on 15-2-2009 at 02:01


For some reason I first saw this as "experiments on my brother"

Another CoCl2 one is to make a fairly strong water solution of it, then ad some acetone. This gives two phases, the organic one being blue from the dehydrated Co(II). I believe this works with nickle salts as well, but the change from green to yellow or brownish yellow is less spectacular.

Amino acids, including MSG, form complexes with many of the transition metals, with copper acting similar to ammonia in giving a deeper blue colour. While not sparks&smoke, giving him coloured transition metal salts and MSG, and letting him see which ones do something interesting and if he crystallise the complexes might be interesting.

And there's always the iodine + strong aqueous ammonia one, sticking with small amounts of iodine.
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Jor
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[*] posted on 15-2-2009 at 03:34


Thanks for you comments!

Many nice ideas here. I'm definately interested in many of them, including:
-Iron wool with halogen vapour.
-TCCA/Acetone + sulfuric acid
-a SMALL hydrogen balloon (is this dangerous?)
-all experiments magpie gave (except the last, see why in my first post in topic ;) )
-artificial sunset (haven't tried this myself as well)
-conc. CoCl2 / acetone. Probably evaporating the acetone after will leave some blue anhydrous CoCl2 as well, or maybe some acetone complex, like CuCl2 does (see woelen's topic 'yet even more copper chemistry...')

How dangerous is NI3.NH3 not_important. Does making 50-100mg harm? if it would go off in a small beaker?

I have some good ideas myself as well, like oscilating reactions (I have malonic, and potassium bromate).

Magpie, by the way, at such concentration of SCN- , no [Fe(SCN)6]3- is formed, just mostly [Fe(H2O)5SCN]2+ and [Fe(H2O)4(SCN)2]+ .


Thank all. New experiments are ofcourse always welcome!

By the way, it was nice to do some experiments with someone else. We cleaned the glass together, etc. That's why I always wanted a lab partner, much more fun! Maybe some time I will.

Magpie, you suffer from the same problem right? :P

By the way smuv, how did you make ethyl chloride so cheaply that you just combust it? :o
Seems it has more useful properties other than burning it for a blue flame :P

You only get the grey flame with ethyl nitrite if you start with potassium nitrite, with sodium nitrite I just get a yellow flame. Bubbling gives small aerosols, with Na+, wich ruin the grey color.
You can see it here in one of my videos on Youtube:
http://www.youtube.com/watch?v=H6KdIBF4BfA

[Edited on 15-2-2009 by Jor]

[Edited on 15-2-2009 by Jor]
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panziandi
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[*] posted on 15-2-2009 at 07:40


Pyro experiments that always get my sibblings and cousins awed are:

glycerine and potassium permanganate

potassium chlorate and sugar

magnesium powder, silver nitrate

magnesium powder and iodine

thermites

(ammonium dichromate volcano is never one they find interesting because it's too slow)

Most of these reactions I do in a piece of folded aluminium foil




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[*] posted on 15-2-2009 at 08:52


Quote:
Originally posted by panziandi
Perhaps thermal decomp of a polymer and collecting the vapours? You can make methyl methacrylate from perspex chips and then repolymerise the product.

You could react magnesium metal with steam in a test tube.

You could try reacting iron wool with Br2 vapours and with I2 vapours in test tubes.

Crack an alkane in a test tube over broken china to make alkenes which you could react with KMnO4 solution and with Br2 solution.

a few ideas there...


Just wanted to chime in along this theme. There is a resin called Kristalex, which is poly[a-methylstyrene]. The various Kristalex's are used for such diverse applications as making faux glass (Hollywood sets), and various casting applications. A destructive distillation (add a little epsom salts) will yield a-methylstyrene.;)
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[*] posted on 15-2-2009 at 09:14


That amount of iodine is safe, you can make it more impressive by using a distint excess of ammonia with powdered iodine, and filtering onto absorbant paper like pager towels to get the complex thinly spread. Tear the wet toweling into pieces and let it dry, with sufficient iodine it makes a loud bang, brown-purple cloud of ipdine, and brown-stain fluff out of the paper.

Polystyrene is easy to crack to styrene monomer, too; the styrenes and acrylics are the easiest plastics to convert back to the monomers.
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smuv
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[*] posted on 15-2-2009 at 11:24


Quote:
Originally posted by Jor

By the way smuv, how did you make ethyl chloride so cheaply that you just combust it? :o
Seems it has more useful properties other than burning it for a blue flame :P

You only get the grey flame with ethyl nitrite if you start with potassium nitrite, with sodium nitrite I just get a yellow flame. Bubbling gives small aerosols, with Na+, wich ruin the grey color.
You can see it here in one of my videos on Youtube:
http://www.youtube.com/watch?v=H6KdIBF4BfA

[Edited on 15-2-2009 by Jor]

[Edited on 15-2-2009 by Jor]


About the ethyl chloride preparation, see the bottom of this thread. I burned it because I had no use for it, I simply made it to analyze the nucleophilicity of Cl- vs Br-. Ethyl chloride is OTC though (for a price), as a freeze spray for temporary pain relief.

In regard to the ethyl nitrite preparation, sodium nitrite was used; although the procedure was much different than yours. This procedure was more of a hassle, but might be better for demonstrations because the rate of EtONO production can be fully regulated.

A slurry of ethyl hydrogen sulfate, sodium nitrite and DMSO were mixed into a test tube. A one hole stopper and an L shaped piece of glass tubing were affixed to make an improvised retort. At room temp, no detectable amounts of EtONO were produced, but with gentle to moderate heating, with a torch, EtONO was evolved. The ethyl nitrite burned with a flame that was light gray, almost white in some portions. A note: no production of the nitro compound was observed, although, not much effort was put into isolating it from the effluent vapors.

I bet if you tried your method, but improvised a retort, you would get an uncontaminated flame w/ NaNO2. Also, it is possible that your KNO2 experiment was contaminated with some violet from the K+.

Some warnings + tips in regard to the TCCA/Acetone experiment; understand that the products are really irritating, although a fume hood should take care of this. Also, to get the best results, make sure the TCCA is finely ground and as much TCCA as possible has dissolved into the acetone before adding the acid catalyst. To be safe, treat the TCCA/Acetone mixture as if it is unstable.

[Edited on 2-15-2009 by smuv]




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[*] posted on 15-2-2009 at 12:10


not_important: Is garden variety Plexi-Glass, Lucite, etc. pretty much just the alpha-methylmethacrylate polymer, or is there some nitrile in there as well, and(or) maybe small amounts of higher homologue acrylate? I would imagine some of the cheapest types of plexi-glass would yield perhaps the purest monomer? Thanks;)
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[*] posted on 15-2-2009 at 12:14


Quote:
Originally posted by panziandi
Pyro experiments that always get my sibblings and cousins awed are:

glycerine and potassium permanganate

potassium chlorate and sugar

magnesium powder, silver nitrate

magnesium powder and iodine

thermites

(ammonium dichromate volcano is never one they find interesting because it's too slow)

Most of these reactions I do in a piece of folded aluminium foil


Just wanted to add one very accessible one along these lines; ethylene diglycol antifreeze and swimming pool HTH. There is perhaps a 3 second delay between addition, and conflagration.
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[*] posted on 15-2-2009 at 13:03


There is a set of books, you might have heard of it before. There are a very broad number of simple experiments which can be done. It's 4 volumes, and can be found in some libraries. It's called Chemical Demonstrations by B.Z. Shakhashiri.
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[*] posted on 15-2-2009 at 21:32


A hydrogen baloon isn't really dangerous. If it's not mixed with oxygen, there's a dull "whomp" and the balloon gets replaced with a fireball for a second or two. My high school chem teacher did this the very first day of class. If you can make enough hydrogen, lead it into soap solution instead.

Place some chips of parrafin wax (ml or two max when melted) in a test tube, heat tilted over flame until the wax boils and you can see fumes fill the tube. Plunge it into ice water and you get a miniature mushroom cloud (and a spray of hot wax). Freezing the boiling hot wax is exothermic enough to ignite the fumes in the tube. (You break the tube, so use a cheap one).

Use a copper coin instead of the iron filings. Bright blue copper nitrate solution and NO2 fumes.

Seconding the boric acid in methanol. On the cheap, heet gas line antifreeze works as-is for this demonstration, I put a few grams of boric acid in one of the smaller containers, pour the whole thing into a raised firepit (big metal dish almost a meter wide) and light it up.




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[*] posted on 17-2-2009 at 10:29


You may be more comfortable (and the whole setup easier) collecting the hydrogen into a thin plastic bag rather than a balloon. You can watch the bag slowly inflate. Zinc pennies (if you have modern U.S. pennies) or zinc in any form, in HCl, makes your hydrogen gas nicely.
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[*] posted on 17-2-2009 at 21:39


Maybe a little Mn2O7 could be a fun one. Whenever I did a couple demonstrations for my friends, that always seemed to be the most impressive. From your description he seems good enough to handle it.
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[*] posted on 18-2-2009 at 00:32


Mn2O7 was my favorite compound when I was younger. About, if not more reactive in some regards, and more brisant is NCl3, which is also more readily prepared. It's related to NI3. And for the sensitivity it lacks compared to NI3.NH3 (though it's shock sensitive too), NCl3 is that much more violently reactive. It's also a bit more powerful than NI3.NH3.

[Edited on 18-2-2009 by Formatik]
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[*] posted on 18-2-2009 at 01:41


An old schoolboy favourite which is probably out of favour now owing to its inherent dangers, is making stink gas. While a dangerous poison it can still be made in relative safety. An easy route to this is heating iron filings/fine steel wool + sulphur in an old ceramic cup on hot coals (OUTSIDE!!). This produces FeS which upon the addition of dilute HCl produces hydrogen sulphide aka marsh gas. WARNING this makes H2S, which is extremely toxic, do not scale up or carry out indoors- do not hold your nose over the reaction vessel etc etc. In fact in today’s nanny state world you should not do this at all…loud sigh :( Doesn’t make it less fun though :)
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panziandi
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[*] posted on 18-2-2009 at 05:26


The UK pennies (the newer bright coloured ones post 1990?) are copper plated nickel because it is cheaper than pure copper (test them with a magnet!).

You can take a "copper penny" and add it to a beaker of conc nitric acid. You'll get vigorous fuming of NOx and a blue solution, you can remove the penny and it is silvery grey! The nickel doesn't dissolve because the concentrated nitric acid forms a passive layer on the nickel preventing further reaction.

They do this in school... technically I think it may be borderline illegal - defacing the Queens image, but I'm sure she wouldn't mind a few pennies being used for educational purposes!

Maybe an interesting experiment for your brother?




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Jor
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[*] posted on 18-2-2009 at 13:18


Thank you for all comments.

Panziandi, I have done the copper coin in nitric a thousand times already, and showed it to everyone of my family ;)
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[*] posted on 19-2-2009 at 03:28


Quote:
Originally posted by panziandi
The UK pennies (the newer bright coloured ones post 1990?) are copper plated nickel because it is cheaper than pure copper (test them with a magnet!).

You can take a "copper penny" and add it to a beaker of conc nitric acid. You'll get vigorous fuming of NOx and a blue solution, you can remove the penny and it is silvery grey! The nickel doesn't dissolve because the concentrated nitric acid forms a passive layer on the nickel preventing further reaction.


Hi panziandi,
I doubt the Nickel to remain unafected by HNO3...actually the former belgian 50 belgian franc coin where pure 7g nickel, I used to dissolve this into HNO3 to get green Ni(NO3)2 also with rapid evolution of NOx fumes, just as Cu does.

I think the core of the coins must be now made of an alloy containing iron...
Just out of curiosity I have taken Euro cents and allowed them to react with NH4OH 12% conc by weight in a closed PET bottle...The coins turned unplated from their copper in a few weeks while blue complex Cu(NH3)4(OH)2 formed...
Let a lot of air above the NH4OH, from day to day, you will see that the solution turns blue and that the bottle depress (O2 consumption). From time to time open the bottle to allow air to come inside...then close the bottle again and shake...the blue solution turns darker and darker and after a few weeks only the silvery core will remain.
Upon exposure to moist air some tiny spots of rust come onto those un-copper-plated coins...so I assume there is some Iron into the core...
My guess is that
Cu + 1/2O2 --> CuO
CuO + H2O --> Cu(OH)2
Cu(OH)2 + 4 NH4OH --> Cu(NH3)4(OH)2 + 4 H2O

[Edited on 19-2-2009 by PHILOU Zrealone]

[Edited on 19-2-2009 by PHILOU Zrealone]




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panziandi
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[*] posted on 19-2-2009 at 04:12


Yeah someone else said they thought the Ni was actually a steel alloy. My chemistry teacher told us (god like 10yrs ago now!) that they were Ni. I for some reason have it stuck in my head that Ni is passivated... must check. Anyway whatever is at the core of the old pennies DOES NOT dissove.



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Jor
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[*] posted on 19-2-2009 at 05:05


As mentioned before on this board, nickel only dissolves in moderately concentrated nitric acid (around 40%), and not in concentrated (50-70%) and dilute acid. Acid concentration is crucial.
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