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Posted

Alright I come to you guys for advice on a physics final project. My entire class is creating and building a rube goldberg device in which a ball is going to travel through a course setting off simple side parts. For one of the parts my teacher wanted some type of fire or chemistry part....naturally I volunteered to do this part and mentioned the possibility of a solid powder burning down the line changing colors in the order of the rainbow.

 

Now the problem is how to construct the device. I was figuring the ball would flip a switch to a power source and most likely a nichrome igniter. I figured I would use an angled piece of metal with a powder trail in it going from color to color. Should I stick with basic star comps or perhaps flare forumulas? I would suspect that star mix would be easier to use. The only problem is I only have experience with red, green, blue formulas....so I have the star formula for those. But I need to order chems for the other colors and I was wondering what you guys thought I should use. I dont exactly have a large budget to just buy a shitload of exotic chems and then experiment with ones that work. I was looking at the russian comps in the composition section however most of those have exotic chems....I do have access to the school lab but I doubt they have most of those exotic chems. So if anyone could offer advice on certain formulae that would work for the colors of the rainbow or any modifications to the device itself (ignition and so on) it would be very appreciated.

Posted

Well the thing is the rinbow or color specttrum isn't like clearly defined colors. They kinda fade into eachother with different shades rather than seperate colors. So what colors are you going to include?

 

I would say red, yellow, green, blue. Maybe mix them some in between the colors to create those intermediate shades?

 

So yellow is all you really need... You can probably get that from NaNO3 which is easy to get a hold of. Since it will just be a dry powder the hygroscopicity (is that a word?) of it won't matter.

Posted
Ask your teacher what chems he does have. You might be suprised. :rolleyes:
Posted
Well as It is for AP physics...my physics teacher just wants to see some different colored flames and is not exactly concerned with the fluidity of the color changes. The true objective is to explain the differences in wavelengths of the light and stuff going into the chem and physics of the light which is rather simple. And since I took AP chem last year I know mostly what they have in the labs. I think I am deffinitely gonna be ommitting some of the colors. I am deffinitely doing red, green, blue. I am 90% sure the school lab has NaNO3...so if they do then yellow is in.....and if they have CaCO3....then orange is in too....and purple is just a mix of CuO and SrX. However I know they dont have perchlorates....but they do have kclo3. Idk I need to go there and make some CuO tommarow using mumble's procedure and will see what else they have. I would like to do the entire veline color system using all the in betweens but that is just not practical when it has to be repeated a few times. Anyone have any better idea than just a simple nichrome wire for ignition?
Posted

Well, nichrome is a choice, christmas lights are a choice, E matches are a choice.

 

You could use a hypergol, maybe causing the ball to tip some water over to ignite a pile of Negative X. -X would ofcourse light any of your starter comps, as it did my leg :ph34r:

 

Just a thought, could calcium sulphate be used to produce a nice orange? This could be a nice, cheap alternative to the carbonate.

Posted
Wow, I cant believe I forgot about xmas igniters. They were all I used to use back in the day and already have about 200 cut up with ends stripped somewhere in my room. I'll probably use thatwith BP in igniter as a prime. Hypergols would be more interesting but I need instantaneous ignition as the rube goldberg isn't going to be that long and I need it to fire while it is going and not after but that depends on the time...in my experience negative X takes a good 30-40 seconds to ignite. Your guess about the calcium sulphate is as good as mine. But depending on solubilities it is possible to create the desired calcium(X) I just need to look up the solubilities.
Posted

A quick note about my CuO proceedure, if they have KOH, substitute in that. The NaOH and Na2SO4 is very hard to get out of the CuO.

 

Sulfate, Oxide, Hydroxide, Carbonate, Sulfide, they're all insoluble. CaCl2, and Ca(NO3)2 would be the best starting materials. Nearly every school will have CaSO4 around. It is known as "drierite", it's a very common desicant with a small portion of Cobalt Nitrate (I think) in it. The Cobalt Nitrate turns from blue to pink as it gets wet, helping to indicate when the drierite needs to be redried. If you just crushed it up as is, it would be fine. The orange band is much stronger than the blue/green the cobalt would create.

 

Another possibility is liquid flames. All but purple would be pretty easy. I would also be worried about barium and strontium contaminates, as well as just a lot of smoke, in the air from solid fuels.

Posted
I did at first consider using methanol with salts added....but how would you go about containing them in a sequential order? just have a couple low walled almost petri dishes next to each other? I was thinking about complications of smoke but my teacher said we would set up my aparatus right next to the windows which open about 3feet high and line every inch of the rear wall of the classroom. I will look into that dessicant compound.
Posted

Calcium sulphate ( possibly hexahydrate, don't remember) is plaster of paris, or so it says on the box. There is probably clay in there so that might muck it up.

 

Please correct me if I'm wrong, which might be the case.

 

I would think it would be hard to transfer liquid flames, that is if enough vapor weren't being produced.

Posted
The only way I could persee the transfer of fire to liquid flames is if there were seperate igniters right over each methanol sample...which is not really possible due to the fact that I might only have one variable power supply possibley two which just wont have enough current to set off all of the igniters...which is why i wanted one powder trail of various compositions with one igniter. There is only one switch that I have the option of using. If the entire rube goldberg was my project I could just have multiple switches to multiple powersupplies with a different color at each switch but that is just not possible as it is an entire class project and my chemistry part is only supposed to be a small part. If anything I will wait for my chemicals to arrive...attempt the powder trail and if it doesn't work due to excess smoke and ask then I would have to go to liquids or scrap the whole plan entirely.
Posted

Blinding is a compliment to a pyro composition, I think. I am looking for a good violet, but if you mixed blue and red compositions up, you could get one, I think. Perhaps the Veline color system? Is that any good?

 

Good luck, its nice to see you get to do this, everyones overprotective over here...

Posted
The only problem with the Veline color system is that is uses Magnalium which I dont have and dont have the money to buy. My mom told me to keep the order small and it was already 50 bucks...she wont be too happy but I should have enough chems to do the desired effects in combination with the chems the school has. And for purple I planned to just use a mix of red and blue....or just pick a comp from passfire or a comp database that appears to be a good mix.
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