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Author Topic: Request help with electrochemistry  (Read 1189 times)
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LabVIEWguru
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« on: November 23, 2010, 05:05:56 17:05 »

I saw an interesting youtube video about extracting components for fireworks. In the video it was shown using a stainless steel cathode and a platinum-coated nichrome  wire anode. ($150.00 USD!!!!) I think these people are in the business of selling electrodes, because I asked about less expensive anodes and that question was ignored. (other questions were answered). I was told that "The titanium is great for the cathode but cannot be used for the anode due to rapid passivation." this means the surface will chemically oxidize and the reaction will not continue.

video: http://www.youtube.com/watch?v=9FyGP-zSpZo&feature=related

My question is: Can I use some other (cheaper!) material for the anode, maybe silver coated wire?

When I was a young boy, chemicals were available at the pharmacy or hardware store. I know I can purchase these chemicals, but I am (1) very paranoid and (2) I don't want to purchase 10 pounds (4kg) just to play with fireworks.
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Ichan
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« Reply #1 on: November 23, 2010, 05:39:50 17:39 »

I am not very sure, but maybe you can try titanium pipe for the anode.

I got mine for my plating tanks from a "special steel" store.

-ichan

EDIT: Other source of titanium is "titanium welding rod", easier to get if you have welder friend.
« Last Edit: November 23, 2010, 06:36:19 18:36 by Ichan » Logged

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« Reply #2 on: November 28, 2010, 06:00:35 18:00 »

The anode cannot be made in Titanium, because Titanium is very fast passivated. All metals are easily passivated when used as anodes, unless they are purposedly used as part of the reaction, let's say as sacrificial anodes or plating anodes. You know very well that anodization is used as a passivation layer on aluminium. Only noble metals can be used in reactions which shall not involve the anode itself. At least this is what I know on the subject. Graphite is sometimes an alternative, but that depends on the actual reaction, I think.
« Last Edit: November 28, 2010, 06:05:05 18:05 by engamor » Logged
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« Reply #3 on: November 28, 2010, 06:26:48 18:26 »

My thought about titanium is based on the fact that almost all anode basket and jigs made from titanium. I never saw titanium passivated (stop conducting electricity) on sulphate based electrolyte, do not know on chloride.

-ichan
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« Reply #4 on: November 28, 2010, 07:23:01 19:23 »

Years ago a friend and I played with electrolysis using the carbon rods from batteries as the electrodes.  They lasted pretty well.
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« Reply #5 on: November 30, 2010, 08:09:58 08:09 »

Yes, carbon rods of batteries can be of help for some test. The problem is to clean them very deeply otherwise the byproducts of the reactions of the pollutants contained in the porosity can led to unforeseen results ... including dangerous ones. Of course this depends on the intended purpose!
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« Reply #6 on: November 30, 2010, 10:18:19 10:18 »

In the next day or so I'll post some links to videos where it is shown to coat the titanium with a magnesium (?) compound to prevent passivization (sp?)  of the anode. Apparently, as engamor pointed out, carbon rods work very well but contaminants lead to unexpected results! At my age, I don't heal up like I used to when my calcium carbide experiment "went south." I was only 15 and almost didn't heal up at all!
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« Reply #7 on: December 01, 2010, 09:55:07 21:55 »

I think, given the issues with electrodes, that making the stuff from bleach might be simpler. Not as good a yield and messier, but it works. Beware of using salvaged carbon electrodes as any impurities from them in the resulting KClO3 might increase its already high sensitivity to friction.

Also, be aware of that sensitivity... KClO3 can easily and spontaneously 'go off' when mixed with fuels like sugar. Be especially careful of larger quantities which can, especially if slightly moist, start to react slowly in the centre. This heats the centre up and before you know it the whole lot is erupting! I have personal experience of this; I've never run across a lab so fast in my life!

Seriously, if you want to play with KClO3, please be very, very careful. I recommend reading this http://www.jamesyawn.com/kclo3/notes.html first. This excerpt sums it up though:

Working with chlorates safely requires substantial precautions and cautious procedures:
- working with very small quantities of any given mixture until the nature of the mixture is well known
- wearing face mask, fireproof gloves, and other suitable protective gear while working with pyrotechnic mixtures including chlorates
- avoiding the use of substances which create sensitive or unstable mixtures with chlorates.  Sugar is one of them.  Others include sulfur, phosphorous and compounds that contain sufur and phosphorous, and many organic fuels.
- avoid storing pyrotechnic mixtures in any tightly sealed container that might serve to build up explosive pressures.
- avoid storing in a hard container such as metal, glass, or hard plastic which could fragment if an explosion occurred
- avoid the use of screw caps or plugs that might cause excessive friction.  If a friction-type of cap is used, it must be kept clean of the pyrotechnic mixture
- avoid packing or ramming of any mixture in a casing without very substantial safety precautions.  Ramming such mixtures in a tube while holding it in the hand is one way amateur pyrotechnists lose fingers.


Unless you have a particular need for KClO3, I would recommend trying another oxidiser. Unless you are thinking of its potential use in a high explosive like a cheddite of course... In that case, be really careful! There are better and easier to make HE compounds.

Sorry if I'm preaching to the converted and you already know all of this, but I would regret not saying it if you had to type your next post one-handed  Shocked


Enjoy, and be safe  Wink
« Last Edit: July 26, 2015, 02:17:17 02:17 by Magnox » Logged
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« Reply #8 on: December 01, 2010, 10:56:10 22:56 »

Thanks! I appreciate the advice. When I was a kid, you could buy various acids, chlorates, nitrates and such right off the drugstore shelves. When I was 14 I purchased calcium carbide (miners carbide) at the hardware store and made a cannon that would shoot a golf ball 1/2 a mile (pipe at a 45 degree angle) One day I had a bit of an "accident" involving acetylene and all these years later, I still have the scars - so I tend to be pretty safety conscious. I had 2nd and 3rd degree burns on my right arm, the right side of my face and burned a lot of hair off. That only needed to happen once before I learned the cautions are put in the organic chemistry books for a reason. Rule 1: Use/manufacture small amounts. When I see the kids on youtube making FOUR HUNDRED GRAMS of flash powder, I just shake my head and wonder if they'll make it another six months! There are some videos of a gent showing how to coat titanium to prevent passivization. I'll post them as soon as I verify it.
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