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hodges
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Platinum Wire vs Platinum Plated Wire
I am planning to do some experiments with platinum. Mainly involving electrochemistry, but possibly using as a catalyst with NH3 and O2 at a later
date.
I see I can buy a foot of #28 platinum wire for $48 here:
http://www.sciencekit.com/category.asp_Q_c_E_440844
I can also buy a foot of #28 platinum <i>plated</i> wire for $10 here:
http://www.scitoyscatalog.com/Merchant2/merchant.mvc?Screen=...
Will platinum plated wire work for experiments, or do I need to get the platinum wire?
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Mr. Wizard
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The main drawbacks I see to the plated wire are holes in the plating, the cut end will show the base metal,not knowing what the base metal is, the
base metal may contaminate the reaction, and if the wire gets hot enough the Pt may diffuse into or alloy with the base metal, and become useless.
A few years ago, I bought a glow plug for a model airplane engine that had a short Pt wire in it for just a few dollars. There were both Pt plugs and
non Pt plugs. I'd buy the quality wire. I looked at the site and the wire is labeled "restricted'. Maybe they won't even sell it to you :-(
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The_Davster
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Get platinum wire from ebay. I saw a foot of pure Pt wire on there for 4 USD a while ago(buy it now type sale). I would go with pure platinum in any
case.
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garage chemist
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Don't get a too thin wire! I don't know what "#28" stands for, but I once got some 0,3mm diameter Pt wire for rather cheap (1€ per 1,5cm) and I was
not happy with it. When being bent only a few times, the wire got thin spots on it and eventually cracked.
Also, it can't support more than 2 Ampere of current, otherwise it gets so hot that solder connections will fail.
As a catalyst for gas phase reactions, thin wire is better though. It would even be good if it was thinner than 0,3mm.
For electrochemistry, get a 0,5mm diameter wire. It supports currents of up to 4 Ampere without getting hot.
Keep in mind that you can't make perchlorates directly from chlorides with platinum (when the electrolyte contains chlorides, the platinum will
dissolve). It is only useful if you can get pure chlorates (KClO3 can be used, its solubility is just not so high at room temp, therefore you need
larger cell volumes- but that's the only problem). Dichromate must always be added to the electrolyte.
And I don't need to repeat that the wire has to be made entirely of platinum. A plating is way too prone to failures.
You will have to spend some money on the wire. Maybe it's best to purchase two diameters- a very thin one for catalysis experiments, and a thicker one
for electrochemistry.
[Edited on 13-6-2006 by garage chemist]
[Edited on 13-6-2006 by garage chemist]
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hodges
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I'm planning on doing some experiments with measuring the potentials of hydrogen and oxygen under a wide variety of conditions. Eventually I want to
come up with a working (though not necessarily practical) fuel cell. I doubt I'll be doing much in the way of electrolysis, except for quick tests.
I do plan to use it as a catalyst as well (such as with NH3) for experiments (not large-scale production).
From the responses here, it does sound like the pure platinum wire is worth the extra cost. I'm seeing costs of around $10 an inch for 99.9% Pt #26
wire on E-Bay. I see the 92% platinum wire is much cheaper (not sure why) but I doubt this is good enough.
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Antwain
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Quick question. If / when I get around to buying Pt wire. what do I want. garage chemist has already blown my first plan out of the water with his
post above. I was thinking "so if its half the diameter its nearly a quarter the price but only half the surface area... lets see how far we can push
this" Also, is 0.5mm perfectly suited to electrochem? Alfa has Pt for $140/25cm 0.5mm diam and $115/5cm 1.0mm diam. I figure 5-10cm is a good length,
but its always good to have some left in case I wanted to make a mg of Ba platinicyanide  . Also is 99.95 good enough or can stuff (as in anything, it will get put through hell i'm sure) eat that that wont eat 99.997? And garage
chemist, I have seen your post about perchlorate from chlorate, so I know its not invincible.
Also if i did buy from a proper chem place do I want annealed, hardened, other? Also, I'm a complete n00b when it comes to ebay. never bought anything
and don't know how to search. I cant find ANY Pt wire on it at any price. Is ebay a real and cheap valid option and if so how long do you reckon I
will be waiting / how the hell do I search for it?
Thanks guys. Also... if you want catalysts they sell (25mm)^2 gauze made from tiny wire (100mesh, 0.003in) for like $160. A lot of money i guess for
something that specific. But I bet it would catalyze reeeeal good 
Actually, one more thing.... I can get 1/20th oz (~1.5-2g) coins for about $80 AUS (at least i got one in 02 for that). Do you reckon I would have any
chance of beating that out and using that, because that would have one hell of a surface area!!!
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The_Davster
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A platinum coin would work nice. I have hung Pt foil( dumpster diving my university , 2x 1cm^2, very thin) off 0.3mm Pt wire for electroylsis. Just be sure the Pt coins are pure, check numismatic sources.
I have gotten around the issues of thin wire melting solder by making the Pt/Cu connection by crimping them well together, and then putting a large
blob of solder on the interface. This is then inserted into a glass tube, and one end melted shut around the Pt just before the solder. When the
amps got high enough to melt the solder, the molten metal had nowhere to go but to the bottom of the glass tube, still submerging the interface.
0.4mm wire held up to 16-20A for 3 days, the glass tube had minor cracking around where the Pt was sealed through the glass.
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Sauron
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For applications where Pt wire is used as a filament, like in some ketene lamp designs (in lieu of more usual nichrome) the plated wire will not do as
everything is based on the resistance per foot.
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Fleaker
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You can use a platinum plated Ti or gold electrode if it is done properly. There is much literature and technical methods on Pt plating. Platinum is
amazingly inert, you'll only damage it really if you're melting lead or copper in a Pt crucible or being stupid and melting it in a graphite crucible
(a no-no). It very very slowly dissolves in hot aqua regia and not at all in single acids. The 92% or 90% stuff is cheaper because it's alloyed with
iridium. Sometimes you get lucky and find someone selling the alloy thinking it is Pt/Ir but it's actually Pt/Rh (love it when that happens).
@Antwain--Pure platinum is pretty soft--the foil is like heavy aluminum foil and can be bent a lot without the risk of it breaking. In my opinion, I
would not buy foil from Alfa when you can get the same purity platinum in a bullion coin and flatten it out. If you have an anvil, it's easy: put it
down, flatten it, then dissolve off iron residues with HCl. Cake. I would buy a small ingot and flatten it out, hell you might even find a jeweler
with a rolling mill who'd do you the favor if you tell him what you're doing. 2g of Pt won't be 80 AUS anymore, Pt is up in price like all the
precious metals.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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woelen
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I have purchased two pieces of wire, one is 99.9% Pt, the other is 95%Pt/5%Ir, both of 0.4 mm thickness. These are perfectly suitable for electrolysis
experiments up to 2 or 3 A. I prefer the 95/5 wire over the other one. It is harder and can be bent into a spring (it has a certain stiffness). The
99.9% wire is very weak and I have the feeling that it easily breaks.
I've also read somewhere that the Pt/Ir alloy is somewhat more inert, even more so than pure Pt. The biggest advantage, however, of the Pt/Ir alloy is
that it is 1/3 cheaper than pure Pt.
Besides these two pieces (25 cm each), I also have 1 meter of very thin wire (0.05 mm) of a Pt/W alloy, 92/8. This is nice for experiments with NH3,
catalytic reactions and so on. It also can be heated to red heat, by passing a current through this (you see it glowing, like the wire in a bulb).
After this heating the wire is still as good as before heating. For electrolysis purposes, this very thin wire is useless.
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Jdurg
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| Quote: | Originally posted by hodges
I'm planning on doing some experiments with measuring the potentials of hydrogen and oxygen under a wide variety of conditions. Eventually I want to
come up with a working (though not necessarily practical) fuel cell. I doubt I'll be doing much in the way of electrolysis, except for quick tests.
I do plan to use it as a catalyst as well (such as with NH3) for experiments (not large-scale production).
From the responses here, it does sound like the pure platinum wire is worth the extra cost. I'm seeing costs of around $10 an inch for 99.9% Pt #26
wire on E-Bay. I see the 92% platinum wire is much cheaper (not sure why) but I doubt this is good enough. |
Be careful with H2/O2 mixtures and pure platinum. While in college I distinctly remember a demo where a balloon was filled with a stoichiometric
H2/O2 mixture and a thin, needle like, platinum wire was inserted into the balloon. The balloon popped, but then the gas mixture ignited. There was
no flame anywhere near the balloon. Shocked the living hell out of me.
\"A real fart is beefy, has a density greater than or equal to the air surrounding it, consists of the unmistakable scent of broccoli, and usually
requires wiping afterwards.\"
http://maddox.xmission.com. |
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Antwain
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Well, I was thinking of just using a coin, instead of wire. I am trying to get another coin like the one I have, but either way, specs are 14.10mm
diam by 1.40mm thick. I was thinking of cutting into it near the top and squishing it into something like a wire, placing the rest between dense
plastic sheet and beating it gently (as per making sodium foil). The aim is to reduce it to ~ 0.5mm thickness, then cut off the thin edges for use in
making Pt compounds. The sticking the wire-like part into a broken off pasteur pipette adding some solder and several strands of copper wire (0.25 or
0.5mm, whatever, I will fill it up with as much as will fit). Heat it gently so the solder melts and wicks and the copper is right on top of the
platinum, then heat more vigorously so that the glass seals well around the platinum.
Anyone worked with platinum before or know how soft it is? Will I be able to work it with a pair of needle nose pliers, into a wire of sorts? Also,
would a good quality vice (jewelers vice, I think) be strong enough to squish it, as that would be even better than a hammer for precision squishing,
to constant thickness.
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dann2
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Hello,
Some info here. I presume the #28 is AWG (American Wire Gauge).
http://www.powerstream.com/Wire_Size.htm
Dann2
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Fleaker
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Platinum is soft enough to roll out into sheet. A jeweler's vice won't flatten it, but it will definitely leave an imprint on the surface. Best bet is
beating it on an anvil until flat. You can draw platinum wire, but it is necessary that you already have the Pt starting bit very close in gauge to
what you're going to reduce it to.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Antwain
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dammit! this is going to all go wrong, I can see it now 
Ah well, at least when I try it and my coin fatigues and falls apart I will have a whole gram and a half of full cream platinum for use in making Pt
compounds. ... And a nasty hole in my wallet 
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chromium
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Is there any reason why homemade platinum plating can not be used for electrodes? There are recipies available for plating this high-priced metal.
When all think alike, then no one is thinking. - Walter Lippmann
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12AX7
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See perchlorate thread (or wheverever I put that). I plated titanium with Pt and I don't know if it's made much perchlorate, but bubbling oxygen is a
start.
Tim
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dann2
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Hello,
There is plenty of reading to be had from the Platinum Review Journals link at the bottom of this page.
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
There is also the possibility of Potters platinum as discussed on this board.
Dann2
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chief
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Cheap source for platinum-metal-electrodes: reed-relais electrodes are plated with metals of that sort, although sometimes it's rhodium. But one of
these coasts less thas 1 $ and contains 2 electrodes.
Has anyone any experiences with these in measuring potentials etc. ?
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Slimz
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http://cgi.ebay.com/PLATINUM-Wire-28-gauge-1-uGems_W0QQitemZ...
Johnny was a chemist’s son, but now he is no more. What Johnny thought was H2O was H2SO4
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Antwain
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Ok, I have sold my soul and for it I received 1x 1/20 oz platinum coin + 5" of 26 gauge platinum wire.
I was thinking of making a pair of platinum electrodes because even though I can't see when I will ever need a platinum cathode It will be good to
have a spare.
What I was thinking.... take 2" of wire and fold it over to create essentially 2x 1" wires. Cut the coin in half. Flatten the coin somewhat and then
fold over, placing the 2 ends of the wire between the platinum 'sheet'. Then beat the coin more gently to make sure that it is stuck together. I
believe I can make a surface area of 1sq cm x 2 sides this way.
The wires can then be stuck up a pasteur pipette with the end snapped off just after where it narrows to a capillary and partially sealed around the
metal. Then a thick copper wire can be stuck down the top of the pipette and some solder put down. Melting this should make a good contact.
Can anyone who has used a platinum electrode (don't just quote resistances at me, I have found that information myself) tell me if 2 strands of this
wire (0.404mm diam) is going to be a good ratio to 2sq cm of electrode area, or do I need more, or would one strand be sufficient.
I'm liking the pasteur pipette idea, because they fit perfectly into a quickfit thermometer holder. I have used them before for gassing. So I can use
a 3 necked flask with an air condenser in the middle to let out gas and stop mist escaping 
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Antwain
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Platinum electrode
Ok. I have made my electrode. I beat out a coin until it was ~ twice the diameter. While it was still strong and difficult to bend at this thickness I
didn't want to push my luck, as it was getting weird at the edges.
I folded the edge over onto 2 *26guage platinum wires and beat it some more... The wires are clearly visible as an imprint on the coin, so I assume
they are well joined.
I stuck these up a pasteur pipette and sealed it up with a MAPP torch. This is what I would do differently... It worked, but it doesn't look the best,
I would recommend using a jet lighter, the torch just put out too much heat.
I stuck a wire down the top with some solder and melted it with a conventional lighter. haven't tested it, but it looks good.
The first pic is a comparison with the replacement coin I bought (for my random coin and stuff collection). The other two are the finished product.
[Edited on 27-10-2007 by Antwain]
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Antwain
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random text so i can post
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Antwain
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dann2
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Hello,
The coin in the first picture looks quite big...........then I see the beaten version alongside the lighter in the last picture and it does not look
quite so big!!
I do not know if Platinum 'work hardens' as you beat it (like steel for example). Heating the coin (too late now I suppose) to red heat would anneal
the beaten metal, so allowing it to be beaten some more. If Pt does not 'work harden' , like Gold, then the above is irrelevant.
From a Guy (GarageChemist) who actually ran Pt wire anodes, a figure he quoted was 4 amps max. for a 0.5mm dia. Pt wire.
What was you soul worth in actual US Dollars???????????
Dann2
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