Sciencemadness Discussion Board

Lead Dioxide Electrodes

mrjeffy321 - 25-10-2005 at 08:47

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?

BromicAcid - 25-10-2005 at 08:54

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.

mrjeffy321 - 25-10-2005 at 14:06

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?

Chris The Great - 25-10-2005 at 14:49

Couldn't you just use an electrode from a car battery, and regenerate the PbO2 surface of defects by electrolysing phosphoric or sulfuric acid?

Eclectic - 25-10-2005 at 15:08

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).

mrjeffy321 - 25-10-2005 at 15:22

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?

chochu3 - 7-11-2005 at 04:01

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.

mrjeffy321 - 7-11-2005 at 10:24

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.

Eclectic - 7-11-2005 at 10:53

Sounds like it's time for an experiment to me. :D

Never accept an expert opinion of "it can't be done".

mrjeffy321 - 7-11-2005 at 16:09

Quote:
Originally posted by Eclectic
Sounds like it's time for an experiment to me. :D

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]

neutrino - 7-11-2005 at 16:36

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?

mrjeffy321 - 7-11-2005 at 19:07

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?

Eclectic - 8-11-2005 at 03:39

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.

12AX7 - 8-11-2005 at 13:19

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

mrjeffy321 - 8-11-2005 at 14:20

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.

12AX7 - 8-11-2005 at 21:34

- 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

Pommie - 13-11-2005 at 16:28

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.

12AX7 - 13-11-2005 at 16:49

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?


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?


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

Pommie - 13-11-2005 at 18:10

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.

mrjeffy321 - 13-11-2005 at 18:34

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.

chemoleo - 13-11-2005 at 19:22

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]

mrjeffy321 - 13-11-2005 at 20:46

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.

BromicAcid - 13-11-2005 at 21:09

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.

mrjeffy321 - 13-11-2005 at 21:31

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.

bio2 - 13-11-2005 at 23:03

.....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.

The_Davster - 13-11-2005 at 23:13

A while back I was able to dissolve lead in vinigar by adding a dash of 35% peroxide. However after the reaction there was some solid white lead compound on the bottom of the beaker that had to be removed before further use.

[Edited on 14-11-2005 by rogue chemist]

Pommie - 14-11-2005 at 05:04

I just tried the Ca(NO3)2 + CuSO4 combo.

I dissolved 118g Ca(NO3)2 in 200mL water and 125g CuSO4 in 200mL. They both dissolved completely as expected. I then mixed them. I instantly got what I can only describe as about 600mL of ice cream consistency gunk. To try and recover something, I topped it up to 1L and have left it to settle. It's now about 25% clear liquid which I can decant. Guess I'll decant and wash a few times to get my copper nitrate. At least I've learnt something - reactions that have CaSO4 as a product need LOTS of water or should be avoided.

Anyone any suggestions beside sticking it in the spin dryer?

Mike.

garage chemist - 14-11-2005 at 06:17

Vacuum filter it through a sintered glass filter. That's what I used for the CaBr2 + H2SO4 reaction to get dilute aqueous HBr.

This also forms "ice cream" like you described, but on scooping this onto the glass filter and applying vacuum, the voluminous precipitate drastically shrinked and I got a good yield of HBr, only minimal washing of the CaSO4 being necessary.

Boiling the liquid with the precipitate also helps to improve the filterability (I made up this word). It coagulates the fine CaSO4 particles into larger ones.

[Edited on 14-11-2005 by garage chemist]

mrjeffy321 - 14-11-2005 at 07:51

So how long is it expected to take for the lead to react with the Calcium Acetate? I expected a few days atleast. The best I can come up with for lead is melted chunks that I can pound out flatter and thinner to make more surface area.
I never through of suspending the lead in the solution, I will try that too.
Quote:
A while back I was able to dissolve lead in vinigar by adding a dash of 35% peroxide. However after the reaction there was some solid white lead compound on the bottom of the beaker that had to be removed before further use.

With the lead I have sitting in the acetic acid right now, there is a very small amount of white powder sitting at the bottom (perhaps the same thingas what your talking about), but I never added any H2O2 to m batch.

chemoleo - 14-11-2005 at 08:01

You mean copper acetate, not calcium acetate.

The reaction can take up to several weeks, depending on the surface area of the lead. Poor molten lead into water, that will give you small pieces (high SA).
Have an excess of lead too.

The end of the reaction is easily told: The CuAc2 colour disappears. Also add some extra HAc to keep the solution acidic.

mrjeffy321 - 14-11-2005 at 10:36

Quote:
Originally posted by chemoleo
You mean copper acetate, not calcium acetate.

Yes, of course, I mean Copper Acetate reacting with lead.

I will try that idea of pouring liquid lead into water.

mrjeffy321 - 14-11-2005 at 18:39

I just got done with phase 1 of the experiment and I have a problem.

I reacted all the Calcium Carbonate with the Acetic acid giving me a bubbly white mixture. I heated it up for a while in the stove, but didnt boil it. I then took it and dumped it in a bucket whcih I then inten added the Copper Sulfate solution. Nothing appears to have happened. I am suppose to get a very thick mixture after the Calcium Sulfate forms, "Like Ice Cream" as one person puts it, I didnt not, mines was still very watery. I am also suppose to be forming a dark green solutuion of Copper Acetate....I did not, I still have a dark blue solution, just like the copper Sulfate was before. I do seem to have a white percipitate that when I stir up the mixture, it becomes light blue, but other than that, I fear that I have done something wrong, my results are not like those described.

If you want to check my math on how much of everything I was suppose to have added,
I reacted about 100 grams of Calcuim Carbonare with about 2.4 Liters of 5% vinegar. Seperately I prepared about a 1 Liter solution of Copper Sulfate by dissolving about 250 grams of Copper (II) Sulfate Pentahydrate crystals in water.

Pommie - 14-11-2005 at 19:56

Quote:
Originally posted by mrjeffy321
Nothing appears to have happened. I am suppose to get a very thick mixture after the Calcium Sulfate forms, "Like Ice Cream" as one person puts it, I didnt not, mines was still very watery.

If you want to check my math on how much of everything I was suppose to have added,
I reacted about 100 grams of Calcuim Carbonare with about 2.4 Liters of 5% vinegar. Seperately I prepared about a 1 Liter solution of Copper Sulfate by dissolving about 250 grams of Copper (II) Sulfate Pentahydrate crystals in water.


You have got much more water than I had. Your light blue colour when stirred is the precipate. You have 1 mole of each substance in 3.5L - I had 0.5 mole of each in 0.4L.

When your precipitate settles, you should end up with about a Litre of the stuff.

Mike.

mrjeffy321 - 15-11-2005 at 17:37

But that wouldnt change the color would it?

I let it settle completely, then decants and filtered off the liquid and I was left with a light blue filtrate. The liquid was a deep blue.
I then boiled some of the liquid down for a while until I began to notice a smell and stopped. At this point, I boiled away about 700 to 800 mL. I had a pale green solid that settled to the bottom and a lighter blue solution, not nearly as deep as before but still very blue. The to my horror, I examined the pan I boiled it in....there is a dark green substance caked onto the bottom. I have scrubbed and scrubbed and put a lot of efort into cleaning it, but I have made little progress.
Right now I am cooling the liquid I just boiled to see if I can percipitate out anything else and desperately trying to clean by pan.

EDIT:
OK, I cooled the remaining liquid to its freezing point (where it was just begining to solidify), and I got no additional percipitate. After letting the solution settle all night, I got a small amount of pale green stuff at the bottom. The liquid above is the same deep blue as it was before I boiled it. So there is something green, but there isnt very much of it, and it isnt in solution.

I had to resort to use very corse sand paper to clean the bottom of the pan. The green stuff that is caked on, it not easy to get off, but it would appear to be the same stuff that is settling to the bottom of my blue solution.

So I must have done something wrong, but what. My only guess is that it has something to due with either the purity of my calcium Carbonate, or the fact that I had very diute solutions of everything, possible preventing the reaction from taking place.

[Edited on 16-11-2005 by mrjeffy321]

Graphite Aerosol!??

SAM4CH - 26-11-2005 at 13:17

Can I use Graphite Aerosol instead of using graphite rods, in aerosol we can paint any surface and it will be conduct electrisity and then I can coat it with PbO2 using lead/copper nitrate solution!!?
Please see this
http://www.a-m.de/englisch/produkte/spray-gs.htm

mrjeffy321 - 29-11-2005 at 21:46

I dont see any reason why not, other than if the layer is too thin, too much graphite might errode before a good coating of PbO2 gets on the electrode. It is definatly something to try I think.


Also, it would seem my previous method of making lead acetate has failed.
I am trying another method now,
I am making some Lead Chloride by reacting metalic lead with Hydrochloric acid (the reaction is going on right now). The I will take that and react it with Sodium Carbonate (I will substiture NaHCO3), to make Lead Carbonate. The I will react the Lead Carbonate with acetic acic to produce Lead Acetate.

neutrino - 30-11-2005 at 03:24

That sounds like it will be dificult given the low solubility of PbCl<sub>2</sub>.

12AX7 - 30-11-2005 at 09:05

Nah. Reactivity is less though. You need to boil it (reflux preferred since HCl is nasty) to dissolve it reasonably fast. As a plus, you can pour off the liquor, cool it and PbCl2 drops out nearly quantitatively (though I forget how much PbCl2 is soluble in cold HCl).

Tim

neutrino - 30-11-2005 at 14:35

Sorry, I was referring to the carbonate step. Neither the product nor reactant are very soluble.

chemoleo - 30-11-2005 at 15:27

Oh dear... axehandle himself did that. Lead dissolves VERY badly in HCl. Mainly due to the bad solubility. I don't think he ever got significant yields out of that.

mrjeffy - by the sound of it, your first step went already wrong.

Calcium acetate is SOLUBLE. When you neutralise CaCO3 with HAc, you should be left with a CLEAR solution, not a white bubbly mixture. Only then you add the CuSO4, which is a CLEAR blue solution.
When mixed, the solution turns dark green, and the CaSO4 precipitate forms, which can be filtered off.
If you didn't even get to that stage, it's no point putting lead into it.

Use 25% vinegar concentrte, that's what I used at the time, and clean powdery CaCO3. REmember you are left with a clear solution, before you even put the CuSO4 in.

mrjeffy321 - 2-12-2005 at 10:35

I got the Carbonate idea from this site,
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
The idea is to get solid Lead Chloride and solid Sodium Carbonate and react them together in boiling water.
As it says,
Quote:

This should produce pretty pure PbCl2. Now, weigh the PbCl2 (You do not have to dry it first). Place the PbCl2 in a container and to every 100 grams of PbCl2 add 50 grams of sodium carbonate. Add 300 ml's of water (or more if it doesn't seem enough) and boil the mixture for about 15 minutes. Stir well. Then, let the PbCO3 that has formed settle and decant the liquid. Add 300 ml's of fresh water and boil again. Let settle, decant and repeat one more time. This should remove any Na2CO3 that is left in the PbCO3.(lead carbonate)



My Calcium Carbonate source is of questionable purity. I am using a cleaning product called, "Bon ami", Which is suppose to be plain CaCO3 without any other "extras" other cleansers put in. The reaction was kind of slow (very slow by a comparison to NaHCO3 and vinegar), and possible left a white color to it since there was a suspension of unreacted/undissolved particles?
Whatever happened, no reaction seemed to occur when I mixted it with my dark blue, clear, CuSO4 solution (except the formation of a mysterious green powder) and I did not continue on after that step.

12AX7 - 2-12-2005 at 12:31

Geez, go out to the garden with a dropper of acid and look for rocks that fizzle when you drip acid on them. More than likely these will be either limestone or dolomite.

In the case of dolomite, you'd want to react with sulfuric acid, wash the precipitate (the solution contains magnesium sulfate and the precipitate is calcium sulfate), add sodium bicarbonate (to give calcium carbonate) until it stops bubbling, wash the precipitate (removing excess sodium sulfate and carbonate), then use this. Should be, oh I'd guess 99% or better calcium carbonate, aka whiting.

In the case of limestone, grind it and use as-is.

For the most part you can ignore the magnesium and iron impurities, so either may be suitable to start with anyway.

Tim