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mrjeffy321
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Lead Dioxide Electrodes
Does anyone know where I could get a Lead Dioxide Electrode for use in an electrolytic cell? Or atleast something that could be adapted for use as an
electrode?
I have looked around, I dont see many people selling them. All I can find is Lead Dioxide in powdered form, which is kind of expensive.
Also, what would be the danger of such an electrode (used as an anode) contaminating the contents of the cell? Would I have to worry about little
[toxic] lead particles floating around, instead of harmless carbon particles like I do now?
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BromicAcid
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Search:
PbO2
More on PbO2 electrodes
And that's this site alone, there are lots of pages online on making them or at least discussing them. However when it comes to buying them it
seems they are only an industrial commodity, imagine if you tried to buy an industrial PbO2 electrode (assuming you could buy just one) it would be
huge! You should have posted in one of the above threads if at all.
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mrjeffy321
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I had seen those threads already, but didnt read them too carefully , since I was more interesting in trying to find a ready made electrode, rather
than making it myself.
But it seems that I will need to make the electrode myself (in addition to the chemicals to make the electrode).
So borrowing on what some other people have tried, and modifying it slightly for my own use, this is what I think I plan to do.
First I need to make a solution of Lead (II) ions. I plan to do this by reacting metalic Lead with acedic acid (vinegar, will 5% do? I think I could
also get 20%). Doing this will produce Lead Acetate, which is plenty soluble in water for my use.
Taking the newly prpduced solution, I will then insert two electrodes. Using a lead cathode (-) and a Graphite anode (+) [but it could in theory be
just about anything, right?], I will electroplate Lead Dioxide onto the graphite anode.
Does the above procedure look good?
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Chris The Great
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Couldn't you just use an electrode from a car battery, and regenerate the PbO2 surface of defects by electrolysing phosphoric or sulfuric acid?
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Eclectic
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Clorate and perchlorate would attack the lead substrate of battery electrodes. That's why you can't just use lead sheet.
Lead acetate solution might work better for lead dioxide plating if you add some sodium or potassium nitrate and maybe a bit of sulfamic acid (from
tile cleaner).
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mrjeffy321
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| Quote: | Originally posted by Eclectic
Lead acetate solution might work better for lead dioxide plating if you add some sodium or potassium nitrate and maybe a bit of sulfamic acid (from
tile cleaner). |
I will be sure to try that. I have some KNO3 that I could easily add when electroplating.
When making the Lead acetate, I had better use the 20% vinegar to try and speed it up somewhat, otherwise, this probably will be quite a slow reation.
What about the effects of using a lead electrode in my chlorate/per chlorate cell? Do I need to be concerned about having little lead particles
floating around in the water...causing impurities in my chlorate? The when I burn the [per]chlorate, having lead there isnt too good of an idea. Or
will this not be a concern when using this type of electrode?
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chochu3
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The 12 volt batteries which I believe to be sold by everlast from wal-mart have PbO2 (red form) and Pb inside them. The batteries are the ones which
you can fill up yourself. It has a tank of sulfuric acid sold next to the battery.
\"Abiding in the midst of ignorance, thinking themselves wise and learned, fools go aimlessly hither and thither, like blind led by the blind.\" -
Katha Upanishad
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mrjeffy321
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| Quote: | Originally posted by chochu3
The 12 volt batteries which I believe to be sold by everlast from wal-mart have PbO2 (red form) and Pb inside them. The batteries are the ones which
you can fill up yourself. It has a tank of sulfuric acid sold next to the battery. |
Really...hmmm, I need to check that out next time I goto Wal mart. I wonder how easy they are to dissasemble and get the electrode out?
I still have not preformed the electroplating yet, as I dont have the more concentrated acedic acid or the lead to do the reaction with me. I talked
ti my chemistry teacher today about it, he has doubts that it will work. Assuming I have a Pb+2 in solution, it may electroplate lead instead of lead
dioxide onto the anode, is what he said.
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Eclectic
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Sounds like it's time for an experiment to me. 
Never accept an expert opinion of "it can't be done".
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mrjeffy321
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| Quote: | Originally posted by Eclectic
Sounds like it's time for an experiment to me. |
Oh yes, definatly.
I was leafing through my chemistry book today, not in search of anything, and I just happen to come accross a page of interest.
It was describing electrochemical reactions, and the example it gave is,
2PbSO4 (s) + 2H2O --electrolysis--> PbO2(s) + Pb (s) + 2H+ (aq) + 2HSO4- (aq)
How about that for proof. The Lead Sulfate is dissolbved in water, releasing the Lead +2 ions into solution. Then through electrolysis, Lead (IV)
diOxide is made. Just like in a lead acid battery.
But what concens me is that both solid Lead diOxide and solid Lead is made in the reaction. Having any lead platted onto my
electrode wont be too good.
So instead of using Lead (II) Sulfate, Iwill use Lead Acetate, since that is what I can make by dissolving lead with acedic acid (I dont have any
sulfuric acid right now).
[Edited on 8-11-2005 by mrjeffy321]
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neutrino
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Pb and PbO<sub>2</sub> should plate on different electrodes, assuming this will work.
Why would the acetate behave any differently than the sulfate?
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mrjeffy321
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I am not saying it will, I didnt mean to imply that.
But if Pb is plated on to the electrode along with the PbO2, will that not comprimise the quality of the electrode? Having a partially lead electrode
would cause lead ions to enter the electroyte solution once the electrode is put into normal use (as an anode) would it not?
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Eclectic
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Pb on one electrode, PbO2 on the other.
Mixed electrolyte of 50/50 PbAc2 and NaNO3 should keep Pb from plating out.
Why is left as an exercise for the student.
BTW: Lead sulfate is almost completely insoluble in battery electrolyte, which is why discharged lead batteries left in summer heat become
"sulfated" and ruined.
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12AX7
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I know matter-of-factly electrolysis of lead acetate will only result in lead metal plating out. I don't know what the presence of nitrate ions
will do.
Tim
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mrjeffy321
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| Quote: | Originally posted by Eclectic
Pb on one electrode, PbO2 on the other. |
Then that will work out quite nicely then.
| Quote: | Originally posted by 12AX7
I know matter-of-factly electrolysis of lead acetate will only result in lead metal plating out. |
Really? But several other people seem to claim experimentally otherwise.
http://www.sciencemadness.org/talk/viewthread.php?tid=1932&a...
If you look at axehandle's post on 18-9-2004 at 09:37 PM (with two big pictures), he seems to conclude it works quite nicely, ss does janger on
20-9-2004 at 12:26 AM.
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12AX7
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- With a significant amount of metal deposited, mind you.
I don't remember any PbO2 being deposited when I attempted the same. No doubt a variety of conditions affect the deposit.
Tim
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Pommie
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| Quote: | Originally posted by 12AX7
I know matter-of-factly electrolysis of lead acetate will only result in lead metal plating out. I don't know what the presence of nitrate ions
will do.
Tim |
On Wouter's page, he uses a mixture of lead and copper nitrate with a copper cathode. I assume that the copper stops any lead from plating out.
Has any one tried this with the acetate. I.E. 250g/L lead acetate and 50g/L copper acetate with a copper cathode?
One more question. I have some calcium nitrate and wondered about converting it to copper nitrate with copper sulphate and then onto lead nitrate with
metallic lead. Is this a feasible path?
Mike.
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12AX7
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| Quote: | Originally posted by Pommie
Has any one tried this with the acetate. I.E. 250g/L lead acetate and 50g/L copper acetate with a copper cathode?
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Hum, hadn't thought of that. Could make a Cu(Ac)2 solution and cementate it partially (with Pb metal), leaving a lead-heavy but still
cupric-colored solution (very quantitative I know  ).
| Quote: | One more question. I have some calcium nitrate and wondered about converting it to copper nitrate with copper sulphate and then onto lead nitrate with
metallic lead. Is this a feasible path?
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Sure, just remember to add the sulfate slowly (over days maybe?) while warm, so it forms large crystals of CuSO4 that are easier to filter and wash.
Tim
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Pommie
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| Quote: | Originally posted by 12AX7
Sure, just remember to add the sulfate slowly (over days maybe?) while warm, so it forms large crystals of CuSO4 that are easier to filter and wash.
Tim |
I assume that was a typo and you meant CaSO4. Will Calcium Sulphate form crystals? I was going to use a large amount of water and let it settle before
decanting. Any suggestions?
Mike.
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mrjeffy321
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I am in the proccess of making the Lead Acetate solution by reacting metalic lead with [20%] vinegar.
It has been about 2 days now since the lead chunk was added to the vinegar, and nothing appears to be happening. I figured the reaction would be
slow, but so far, very little if anything has happened. Is the vinegar too dilute? Do you think it is done perhaps? and all the acetic acid has
been used up? it still smells like vinegar.
I could test it by adding some Calcium Hypochlorite and percipitate out some Lead Dioxide, but that would of course ruin my solution.
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chemoleo
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Numerous ways have been described that involve making lead salts from lead metal.
I'd add H2O2 for starters.
Otherwise - try using a Cu(Ac)2 solution with lead metal. This produces Pb(Ac2) and Cu.
Search the PbO2 and PbO threads for more details.
[Edited on 14-11-2005 by chemoleo]
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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mrjeffy321
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I was wondering why simply reacting the straight metal with the acetic acid will not work [very well]? Why not just lead + acetic acid - > Lead
(Ac)2,
or Copper + acetic acid -> Cu (Ac)2 ?
Why be some complicated and go the long way around by first reacting the acetic acid with calcium carbonate, then reacting the calcium acetate with
Copper sulfate, then reacting the Copper acetate with lead. Lead is above Hydrogen in activity series, it should be displacing the Hydrogen from the
acid to form lead acetate directly.
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BromicAcid
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| Quote: | Why not just lead + acetic acid - > Lead (Ac)2,
or Copper + acetic acid -> Cu (Ac)2 ? |
The copper one is pretty obvious, it lies below hydrogen in the activity series (at least according to mine, there is some variation in some tables in
some books). However lead is only slightly above hydrogen in my activity series so yeah it may displace hydrogen but its not that favorable, it is
slow, even slower with acetic acid, if you had a nice strong haloacid you get a nice dissolsion rate (axehandle tossed a large hunk of lead in HCl and
it bubbled vigorously for days) but with acetate its slower... much slower... I once tried to dissolve lead powder in acetic acid with no luck, the
powder did not dissolve immediately and the powder just clumped together over time.
Lead acetate was origionally made (at least some of it) by hanging lead plates over a vat of acetic acid, the lead acetate being scraped off
periodically. What the key ingredient was here was air, bubbling air though lead in acetic acid will increase the dissolution rate but it may lead to
some carbonate impurites that would have to be removed (further acidification and boilng likely). Really though my point is, although the reaction
happens, lead is so close to hydrogen that the reaction is just slow. In a similar experience I tried to dissolve bismuth in HCl, and it
wouldn't even bubble but it lies above hydrogen in the activity series, nitric dissolve it no problem though.
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mrjeffy321
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Alrightly then,
I am planning to go the long way around making Pb (Ac)2 starting tomorrow and ending who knows when.
I probably will use about 100 grams of "Bon Ami" cleanser, which is suppose to be plain Calcium Carbonate with no addititives, reacting it
with about 2.3 Liters of 5% vinegar (no sense in using the concentrated stuff for this reaction).
The I will boil it down until I start getting a percipitate, then add the Copper (II) Sulfate solution. Filter, cool, filter.
Then I will get a couple lead chunks and toss them in and wait.
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bio2
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.....then I will get a couple lead chunks and toss them in and wait.......
You will be waiting a looooong time too.
Even using very fine lead filings (or copper) it takes days when placed in a strainer suspended above the acetic acid (glacial) with air slowly
bubbled through. Place a loose cover or reflux condenser over the strainer and stir it around a couple times a day. Rinse the acetate off the filings
with water when it starts clogging up the works.
This method works well and after a few days with a large strainer a kilo or two will be had.
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