Sciencemadness Discussion Board

PbO2

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Quince - 12-6-2005 at 02:17

Quote:
Originally posted by chemoleo
Well here it goes... the dissolution of lead metal with cheap OTC materials. I copied parts over of what I posted at E&W already:

Can the last step be speeded up with electrolysis or peroxide?

Copper acetate can itself be made by electrolysing a copper anode in vinegar (graphite cathode).

[Edited on 12-6-2005 by Quince]

Cyrus - 12-6-2005 at 12:54

Nah, I don't think you need to speed it up.

With stirring a few times a day to knock Cu off of the lead, and a HUGE excess of lead (lots of surface area too, lead turnings are easy to make) it only took 2-3 days for the solution to become colorless.

Quince - 12-6-2005 at 23:49

So I made copper carbonate and added a slight excess of vinegar, but it was going too slow so I started adding the lead filings while it was stirring.

The solution became darker blue as more copper left the carbonate form, and copper dust was settling to the bottom. But then -- WTF!

Instead of the solution becoming clear, as I was adding more excess of lead, it became milky grey, and the copper color of the dust also changed to grey! After filtering through a coffee filter, there's still a lot of fine grey dust in the filtrate. To test the solids, I put them in a bit of HCL with H2O2, and a milky green liquid with white-grey precipitate formed. I'm guessing the green indicates copper, but what the hell is the precipitate, lead oxide?

So I don't know, do I have lead acetate in the filtrate or not? Is the grey stuff probably just the excess lead? Rubbing the solids between my fingers, I don't see any of the copper color that was there at all.

neutrino - 13-6-2005 at 02:31

It sounds to me like either your lead was impure or the reaction stopped prematurely (as a result of too much lead), leaving undissolved lead particles floating around. The white precipitate would be PbCl<sub>2</sub>.

12AX7 - 13-6-2005 at 03:20

Lead + carbon dioxide = PbCO3.

It was probably entering solution as normal, then combining with carbonic acid that hadn't had time to leave solution.

Tim

Quince - 13-6-2005 at 04:03

Wouldn't the vinegar dissolve the carbonate? The solution is still acidic. Can I assume that there is some lead acetate in the solution, as that was my goal, and that all the copper would have been be precipitated?

[Edited on 13-6-2005 by Quince]

12AX7 - 13-6-2005 at 05:02

Hm true, it ought to dissolve carbonate. The acid may be too weak though, seems to me a double excess (or more) is needed to dissolve some things. If there was an excess of lead metal, yes it should be only lead in solution.

Tim

Cyrus - 13-6-2005 at 08:58

Quote:
Originally posted by Quince
...Rubbing the solids between my fingers...


Hmm. You might want to be (more) careful w/ lead compounds, even if they are in a solid form. I don't need to start listing off the various MSDS sheets and all that stuff, do I?;)

Quince - 13-6-2005 at 12:03

Bah, the ancient Romans used lead pipes for drinking water, and they did fine...oh, wait... :D

[Edited on 13-6-2005 by Quince]

Oxydro - 13-6-2005 at 14:35

Actually my Mom's Aunt's house in Leven, Scotland still aparently has lead pipes. She's in the high nineties, so no obvious ill effects! Very little lead evidently is dissolved, especially once the pipes have been used for a while.

Quince - 13-6-2005 at 14:41

I'd be worried about her fertility.

neutrino - 13-6-2005 at 16:20

Probably the scale in the water has built up a protective layer on the inside of the pipes. That's one of the reasons Romans didn't all suffer from lead poisoning.

Quince - 13-6-2005 at 18:31

I don't know about that. Quoting from http://www.reevesjournal.com/CDA/ArticleInformation/Retrospe...
Quote:
Still more alarming was the conspicuous pattern of mental incompetence that came to be synonymous with the Roman elite. This creeping cretinism manifested itself most frighteningly in such clearly degenerate emperors as Caligula, Nero, and Commodus. It is said that Nero wore a breastplate of lead, ostensibly to strengthen his voice, as he fiddled and sang while Rome burned. Domitian, the last of the Flavian emperors, actually had a fountain installed in his palace from which he could drink a never-ending stream of leaded wine.

Quince - 13-6-2005 at 22:29

I don't understand this. After I filtered the solution, it was still very light blue, so I threw in a chunk of lead. The lead didn't turn coppery, it turned dark grey-brown. Now, I had previously used a steel file to file down the lead, could contamination from the file be doing this? The color looks similar to lead sulfide, but I don't see how that can be.

[Edited on 14-6-2005 by Quince]

neutrino - 14-6-2005 at 02:21

Sorry for straying off topic here, but the reason the rich had lead poisoning was different. They used to boil sour wine (vinegar) in lead pots and sell the lead acetate thus obtained to the rich (it was said to taste like sugar.)

sparkgap - 14-6-2005 at 03:59

Well, lead acetate WAS called "sugar of lead" in the olden days, at least before the deleterious effects of using this sweetener became evident.

It is said that the mechanism of its taste is similar to that of sugar in that they interact with almost the same set of receptors.

sparky (°_°)

Pyridinium - 14-6-2005 at 08:37

Quote:
Originally posted by Quince
I don't understand this. After I filtered the solution, it was still very light blue, so I threw in a chunk of lead. The lead didn't turn coppery, it turned dark grey-brown. Now, I had previously used a steel file to file down the lead, could contamination from the file be doing this? The color looks similar to lead sulfide, but I don't see how that can be.

[Edited on 14-6-2005 by Quince]


Try taking a sample of the solution and diluting it about 1:10. Try plating some copper out on a piece of lead using this solution. See if the habit of the plated metal is different this time. It may be that you are getting copper, but oftentimes the metals that plate out rapidly from concentrated solutions don't look at all like their normal selves.

Other than that possibility, we'd have to go over the species in solution (including possible contaminants) and see what else could be forming.

Cyrus - 14-6-2005 at 09:50

That sounds like copper to me. The copper sludge that forms really doesn't look at all like shiny copper. Try putting an iron nail in copper sulfate or copper acetate- the copper formed will probably closely resemble the stuff you're wondering about.

The light blue color of the solution dissapearing would be another indication that it is copper.

Be careful with lead dust/filings! I think turnings are better because there's no dust involved, they have plenty of surface area, and they probably can be easily removed from the copper sludge.

Cyrus

Quince - 14-6-2005 at 11:22

I've made a new batch of copper acetate, and as I don't want to ruin this one with the possibility of contaminated lead I was using, I'm wondering where to get pure lead.

12AX7 - 14-6-2005 at 13:34

Pure lead was (and to a small extent still is) used for sealing cast iron drain pipe joints. Matter of fact, there's a 5 pound ingot on the shelf down at Ace Hardware.

Tim

The Chain

MadHatter - 15-6-2005 at 06:19

Look for metals higher up on the chain as a possible source of contamination. There won't
be too many: Silver, Mercury, Platinum, Gold. Lead can displace any of these.

Lead "sugar" Acetate ? No wonder Rome fell !


[Edited on 15-6-2005 by MadHatter]

Quince - 15-6-2005 at 06:41

My second batch worked OK -- that is, until I accidentally knocked off the beaker with a couple of grams dissolved lead acetate off the radiator it was on for evaporation. I spilled it all over me and broke the beaker...

Pyridinium - 15-6-2005 at 07:44

Quince, here's a link for you

http://www.chelationtherapyonline.com/articles/p113.htm

Pb(OAc)2 can be absorbed through skin. I do not know the rate of absorption without looking it up.

You were wearing gloves and a lab apron, I hope?

Edit: Bromic it looks like you're right... did some further reading:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&a...

In that study, Lead acetate is only slightly more absorbed than lead oxide, which itself is basically not absorbed at all.

The calcium supplements (and magnesium) will help anyway. Calcium disodium EDTA is even better.

[Edited on 15-6-2005 by Pyridinium]

BromicAcid - 15-6-2005 at 11:32

Lead acetate isn't too readily absorbed, I would hardly worry about it, just take a bunch of calcium supplement tablets and don't give it a second thought.

Quince - 15-6-2005 at 19:37

Well, I have to do it a third time now, that's what I was pissed off, besides the fact that I've only one beaker left. I have no place left in my room to keep all my labware, so I've basically piled it all on an armchair...

Photos

12AX7 - 23-6-2005 at 23:52

Making lead acetate.

First off, the lead oxide. This was created electrolytically with a potassium chlorate solution (I would prefer sodium but I don't have any on hand) plus other ingredients (KClO3 alone seems to turn basic and plate lead out?), washed and calcined until orangish yellow. PbO is a light yellow and this is much darker. It's supposed to turn orange/red (Pb3O4) but it hasn't in an hour of good oxidizing heat, any thoughts on that?

Maybe 50-100g here. Haven't weighed it yet.

Tim

LeadOxide.jpg - 55kB

12AX7 - 23-6-2005 at 23:56

Copper acetate solution. Basic copper carbonate (obtained as posted http://www.sciencemadness.org/talk/viewthread.php?tid=271&am...) dissolved in vinegar. But it isn't very well dissolved, it's quite turbid and shows no signs of settling. I have heated it with no change. What's going on?

It plates lead quite admirably, but the layer seals instead of flaking off. Does it need agitation, or less pure lead? (Mine's about 99.9%, it forms crystals on solidification, at least it used to, might be 99.5% after as much use and remelting as it's gone through.)

Tim

CopperAcetate.jpg - 20kB

Quince - 24-6-2005 at 00:05

Interesting. My copper acetate is not green but deep blue.

12AX7 - 24-6-2005 at 00:08

Had a feeling about that. Does it change color on dilution? (Does mine for that matter, hm better check that.) Addition of Cl ions? Maybe my carbonate contains residual Cl complexes.

Tim

Quince - 24-6-2005 at 00:16

Your carbonate in there is green as well. It should be blue.

I made the carbonate by mixing a sulfate solution with sodium carbonate (washing soda or roasted baking soda) solution. Sulfate supposedly is sold in hardware stores, but I've still got some left that I brought over from the Old World a dozen years ago...

zoomer - 24-6-2005 at 07:38

Quote:
Originally posted by Quince
Your carbonate in there is green as well. It should be blue.

Metastable basic copper(II) carbonate, Cu3(CO3)2(OH)2, results from the process you describe with room temp materials, and is a light blue in powder form. However, when oxidized, that material converts to the green stable form, Cu2(CO3)(OH)2, which is what appears to be in the pic in the referenced thread. Both dissolve nicely in acetic acid to form dark blue copper acetate.

12AX7, that ain't copper acetate. :) I'm sure you didn't use heavily chlorinated tap water, right? It's also possible that the green is some form of iron. I've found that to be a common impurity in "root killer" copper sulfate.

Z

[Edited on 24-6-2005 by zoomer]

12AX7 - 24-6-2005 at 11:57

Yeah I'm not concerned about the carbonate, malachite is green after all, and azurite eventually pseudomorphs into malachite. I am concerned about the acetate though, if it's always blue then something is indeed wrong. I didn't dilute it any, vinegar is dilute enough, so it must be fixed, in the carbonate.
Could it be something like, uh, (CuCl4)2CO3(OH)2?

Tim

zoomer - 24-6-2005 at 12:10

Or possibly Cu2Cl(OH)3 (which would make it an analogue of atacamite)?

The Cl (or Fe) may have been introduced in the copper sulfate itself, the water used to dissolve it, or by some really cheap vinegar. :)

Z

12AX7 - 24-6-2005 at 14:18

I started with self-made acidic CuCl2 solution, not sulfate. It could certainly be the source of green.

So how about the turbidity?

Tim

Doh!

zoomer - 24-6-2005 at 18:32

Sorry about the sulfate comments, my bad, got my threads mixed up.

Dunno, I'll see if I can reproduce it, that might answer the question about process, anyway.

Z

UPDATE -- I can't seem to repro your result, but that may have everything to do with the brand of shock. I use a local brand by Pool Time.

Z

[Edited on 27-6-2005 by zoomer]

Cyrus - 28-6-2005 at 20:00

Well, I decanted solution from the PbO2 I had made earlier 5 times, filtered it, rinsed it with dH2O, and set it to dry in a dessicator. This took to long, so I let it dry in the open. Then I put it back in the dessicator, and it dried nicely.

Anyhow, enough water had accumulated in the dessicator to make the CaCl2 liquid, and a week or so later I knocked over the dessicator, spilling the PbO2 inside and getting CaCl2 all over it. :(

I really don't feel like purifying it again.
I'm getting a good distilling setup to make some HNO3... so maybe I'll just use lead nitrate for electroplating/making PbO2 anodes.

Quince - 10-7-2005 at 18:11

I was evaporating the water from the lead acetate I prepared by boiling in the microwave. Unfortunately, later in some datasheet for the substance I read:
Boiling Point: ca. 100C (ca. 212F) Decomposes.
Decomposes? WTF! Does that mean what I've ended up is no good because I boiled it? Looks like whitish crystals to me, with a very slight tint of blue from remaining unreacted copper acetate, except a mark of brownish green in the center where it got the hottest. Should I assume the white crystals aren't lead acetate anymore due to heat decomposition?

12AX7 - 10-7-2005 at 18:17

Which reminds me, I've had an (reddish; ferric acetate color?) lead acetate syrup drying over the warm stove (no, no food is being prepared on it ATM :P ) for the last two weeks. And uh, yeah... kind of lacking crystallization here...

Tim

S.C. Wack - 10-7-2005 at 18:49

The 100C figure is probably the point where it begins to lose acetic acid. It probably isn't a good idea to boil it or leave solutions exposed to air for a long time, it forms basic salts and absorbs CO2.

Quince - 10-7-2005 at 19:05

12AX7, there won't be crystallization until almost all the water is gone if it's very warm. When there's only a little water left, in my case it formed a very viscous substance, which crystallized upon cooling.

Maybe vacuum drying at 90*C is the way to do this.

I don't think air is a problem, since the procedure for making it directly from vinegar and lead needs the mixture being exposed to the air for months to a year:
http://www.sas.org/tcs/weeklyIssues_2005/2005-05-20/feature1...

[Edited on 11-7-2005 by Quince]

S.C. Wack - 10-7-2005 at 22:02

Yes, that process has been known for a very long time - as a preparation of basic lead carbonate "white lead".

The vinegar dissolves the lead, forming acetate which becomes a basic acetate, which absorbs CO2 from the air.

Inorganic Preparations says that the basic acetate doesn't crystallize and somewhat prevents the normal acetate from doing so.

Yes, I have personally dissolved lead with vinegar, and attest that in air the initial acetate crystals on the surface of the lead crumble into insoluble powder, and clear solutions of acetate turn cloudy and precipitate crap. It takes a while but I assure you that it happens, in a major, unsubtle way.

verode - 2-8-2005 at 19:34

very easy:
Lead electrodes with conc, sulphuric acid H2SO4 (electrolysis)

Pb + electrolysis ----yields Red Coated PbO2 and very resistent to chlorine you may use later..like electrode

[Edited on 3-8-2005 by verode]

Fleaker - 2-8-2005 at 20:40

IIRC, you can buy lead *monoxide* as litharge for flux/fire assaying for a decent price. I'm sure there's a thermal way to make the monoxide into dioxide.

Best Solvent!

SAM4CH - 24-10-2005 at 14:57

What is the best solvent that could dissolve lead dioxide (PbO2) powder completely!?:(

12AX7 - 25-10-2005 at 08:17

Hmmm, well it's not water. Molten NaOH? But that forms a compound so it's not acceptable. You might be able to form a liquid solution with neighboring oxides e.g. Tl2O, In2O3, Sb2O3, etc.

But I don't know why you would specifically want it in liquid state... somehow I get the distinct feeling you either don't know how to communicate your thoughts or you don't know what the heck you're doing.

Tim

SAM4CH - 26-11-2005 at 14:02

Is this method work for plating lead dioxide? (Electrooxidation of lead acetate in acid solution.14 Lead acetate (100 g) was dissolved in 0.5M acetic acid solution. A platinum anode and lead cathode were suspended in the solution and a current of density 1.0 mA cm-2 was passed. The deposit was ground and washed with water.)!!
If it is work for which one PbO2 will plat on +Pt or on -Pb!?
Thanks

Nerro - 27-11-2005 at 03:03

On a small sidenote I recently dissolved Fe in HAc 80% and H2O2 30% with great succes. The Fe dissolved extremely quickly. Perhaps this is an idea for lead?

[Edited on 27/11/2005 by Nerro]

jpsmith123 - 27-11-2005 at 16:14

The platinum anode will be plated with PbO2.

What I want to know is, will it be the alpha or beta form of PbO2?
Quote:
Originally posted by SAM4CH
Is this method work for plating lead dioxide? (Electrooxidation of lead acetate in acid solution.14 Lead acetate (100 g) was dissolved in 0.5M acetic acid solution. A platinum anode and lead cathode were suspended in the solution and a current of density 1.0 mA cm-2 was passed. The deposit was ground and washed with water.)!!
If it is work for which one PbO2 will plat on +Pt or on -Pb!?
Thanks

SAM4CH - 28-11-2005 at 07:43

It is beta form..
I want to ask about using graphite aerosol .. is it a good idea to paint any surface with conductive graphite paint.. is it will work to make PbO2 from lead/copper nitrate solution.!!?

[Edited on 28-11-2005 by SAM4CH]

jpsmith123 - 28-11-2005 at 12:54

Hello SAM4CH,

I'm wondering, how do you that it is beta form that is deposited form lead acetate/acetic acid solution, do you have a reference dor that?

Also with regard to your graphite coating, I can't say from experience, but as long as it's a conductor and as long as it's compatable with your plating solution, it should work. (I assume you will make your electrical connection directly to the PbO2).

Regards,
Joe

SAM4CH - 11-12-2005 at 13:55

What about Silver for using as anode for plating Lead Dioxide from Pb-Cu/Nitrate solution!??

12AX7 - 11-12-2005 at 16:04

Sure? I don't see why not, since it gets covered immediately.. after a moment your anode surface becomes PbO2 plating on PbO2... LOL

Actually using it is different matter, bad things probably happen... although in a chloride electrolyte, insoluble AgCl would form, no?

Tim

SAM4CH - 12-12-2005 at 14:12

I perpared solution but it is no PbO2 on Silver anode!!? the solution became slightly colloidal with white color!!

Oxidizing PbO2

12AX7 - 4-5-2006 at 18:17

I'm thinking about Mn(III) and (IV) tonight. I wonder is there any reasonable way you could oxidize Pb(II) with them? Mn is a pretty strong oxidizer, though I'll have to check since Pb(IV) is pretty strong itself.

How would the reaction proceed? Both make brown oxidized smudge. Mn(III) is sort of soluble in acid (very burgundy :) ), but it seems to hydrolyze like nuts. Plus, it would take nitric to allow Pb(II) ions in solution (unless PbSO4 ppt can be oxidized). Hydrochloric acid would be long ago oxidized by either product, so that's no good.

Tim

kazaa81 - 6-5-2006 at 17:12

Can one reduce the sodium plumbate (produced by fusing NaOH with metallic Pb) to a lead-only salt (without sodium)?

Thanks

12AX7 - 6-5-2006 at 19:13

Quote:
Originally posted by kazaa81
Can one reduce the sodium plumbate (produced by fusing NaOH with metallic Pb) to a lead-only salt (without sodium)?

Thanks


Er, wasn't it posted earlier that Pb basically doesn't respond to alkali?

Anyways, do you mean the acid ion (plumbic/plumbous) or anhydride (which would just be the oxide), or a lead salt of the lead anion (i.e., plumbous (II) plumbate (IV), otherwise known as, get this, Pb3O4)?

I'm sure adding HNO3 to drop the pH will free plenty of the acid component, as with any insoluble acid compound (borate, etc.).

Tim

12AX7 - 6-5-2006 at 23:37

Quote:
Originally posted by BromicAcid
Then take your lead salt and add the hydroxide of your choosing, like NaOH to precipitate the lead hydroxide. Take the lead hydroxide and add a hypochlorite like Ca(OCl)2 or possibly NaOCl and your lead dioxide will precipitate out.


Seems to work well- I grabbed some crude PbCl2, neutralized what acid was left as well as the salt with some NaHCO3 (hmm, I'm out of it), added Ca(OCl)2 flakeybits, hmm turning color good, yellow, drab ugly brown, eventually to a "vivid" brown. Oh noes, I smell chlorine.. better...um... I know, limestone gravel!

And that's where I've left the experiment for the night. Tomorrow I'll see how the product looks and compare it to other PbO2 I've collected (mostly electrolytically).

Edit: looks good. Got less than I expected, but reasonable I suppose. Solution was still acidic (*cough* chloriney) despite the gravel, oh well. Color is comparable to my electrolytic PbO2, but cleaner. :D A lot like clay, but still filtered reasonably- a lot of fine particles still got through though.
/Edit

In other news, my PbO junk is ever so slowly dissolving in vinegar. It's weak ass, but cheap, 4% stuff. I dropped half a pound of PbO to a gallon of the stuff (~4L), which should be about right. I also added what PbAc2 I made a long time ago, all contaminated with probably Fe. The vinegar solution is now brown. :rolleyes: Question: what's the azeotrope for acetic acid, and is it affected by the salt present? ISTR it's something low in acid (3%?), which is dangerously close to all my acid evaporating from solution. That doesn't make sense to me since GAA is hard to make.

Tim

[Edited on 5-7-2006 by 12AX7]

My try with PbO2 electrode

quest - 23-2-2007 at 05:06

Hi guys,
I tried making pure PbO2 electrode today.
I used 2 shits of Al 3 m"m thick and used electrolysis in PbNO3/CuNO3 solution.
The current was 1.05 A and the voltage about 2 V. I warmed the solution to 55 C.
After an hour I came to see if this worked and found that my anode has corroded a little and on my cathode I got very thick Cu coating.
the anode look a little gray but this isn't coating, I tried scraping the gray coat and it just don't scrap.
*The anode became less thick too.

is there any reason for not using Al electrodes in this experiment?

anode:


catohde:


the cell:


[Edited on 23-2-2007 by quest]

12AX7 - 23-2-2007 at 10:00

Obviously, aluminum is NOT a suitable substrate. Seems obvious to me given its reactivity (especially with copper in solution, especially as the anode).

Tim
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