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Author: Subject: The lead salts preparation thread!
densest
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[*] posted on 24-2-2010 at 16:36


Cd is used to color glass - some "crayon" yellows,reds, and oranges.
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Panache
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[*] posted on 25-2-2010 at 03:33


Quote: Originally posted by 12AX7  


Calcining the Pb(OH)2 produces a yellow to drab orange product, which should be PbO with some Pb3O4. I have never been able to produce bright orange Pb3O4 thermally.


Tim

Why do you think this is? Are you certain of your Pb(OH)2?
When making some Pb(IV)Acetate late last year i had begun to go down this road as it seemed the logical way to Pb3O4, well I got as far as collating some lead scraps to begin when i found Pb3O4 for sale not shy of 1km from where i live. That made life much easier, but it appears from your experience i may have struggled making the Pb3O4 thermally.
For those interested in Pb(IV)Acetate the method in Brauer works as described, i used the method with acetic anhydride, am unsure regarding the method that is mentioned afterwards where the temperature is kept lower and no AA is used.




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[*] posted on 25-2-2010 at 12:28


This is what I got from roasting:



Maybe it wasn't hot enough, maybe it was too hot, maybe it was too uneven. Dunno.

Tim




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Panache
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[*] posted on 25-2-2010 at 19:41


Quote: Originally posted by 12AX7  
This is what I got from roasting:

[/img]

Maybe it wasn't hot enough, maybe it was too hot, maybe it was too uneven. Dunno.

Tim


I guess you weren't shocked when the commonly referred to procedure failed, how accurate is your temperature control in your kiln, can it be calibrated. I mean one really has to squint quite hard and be quite away from the srceen to see much orange in that sample. Whereas the commercial sample, which i dried at 200 overnight as per Braeur, is well, as you can see.

Image010.jpg - 18kB

[Edited on 26-2-2010 by Panache]




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[*] posted on 25-2-2010 at 20:05


That looks like good pigment-quality "red lead", Pb3O4, Panache. Although out-of-favor in final-coat paints because of the toxicity of Pb, it is still used as a pigment in timber paint primers, and in pottery glazes.

[Edited on 26-2-10 by JohnWW]
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[*] posted on 26-2-2010 at 02:10


Quote: Originally posted by JohnWW  
That looks like good pigment-quality "red lead", Pb3O4, Panache. Although out-of-favor in final-coat paints because of the toxicity of Pb, it is still used as a pigment in timber paint primers, and in pottery glazes.

[Edited on 26-2-10 by JohnWW]


Spot on John
Came from an artisan pigment supplier, for those fine art painters wanting to grind their own oil paints. I thought it was cheap $30.00 for 500g. I mean some poor dude out the back of the store has to repackage it.
They began to give me the 'moron's' treatment before i cut them off deftly saying 'yes yes i know, but i'm not using it to paint with' as the cautions were in regards to grinding it.
'Oh what are you using it for?', i had the attention of three shopkeeps and a customer now.
'I'm making tetra ethyl lead' i replied
'Whats that used for?'
Oh how quickly we forget. One of them was older as well. tut tut.




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[*] posted on 1-3-2010 at 06:23
Lead(II) acetate query


The photo 12AX7 posted of Lead acetate looks exactly like the photo at this site: http://webpages.charter.net/dawill/tmoranwms/Chem_Pb.html

This is how the person at the site posted above said he produced the Lead acetate:

Quote:
'Here's some more lead acetate. This was produced by dissolving stock lead oxide (the calcined stuff) in vinegar, however much a gallon of 4% acetic acid would take.'


SO...Can PbO (or is it PbO2) + vinegar/weak acetic acid be used to prepare lead (II) acetate or not? :)

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[*] posted on 1-3-2010 at 08:14


Quote: Originally posted by rajip  
The photo 12AX7 posted of Lead acetate looks exactly like the photo at this site: http://webpages.charter.net/dawill/tmoranwms/Chem_Pb.html
Holy non-secret identity!
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[*] posted on 5-3-2010 at 04:57


Quote: Originally posted by watson.fawkes  
Quote: Originally posted by rajip  
The photo 12AX7 posted of Lead acetate looks exactly like the photo at this site: http://webpages.charter.net/dawill/tmoranwms/Chem_Pb.html
Holy non-secret identity!



I get the sarcasm but could someone clear up the air (pun intended) for me?

CFan PbO or PbO2 be produced in a furnace or kiln from lead metal, and if so how?

Wikipedia states that litharge (PBO) + acetic acid (does this include weak solutions like vinegar?) can be used to form lead (II) acetate, is that true?



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[*] posted on 5-3-2010 at 06:39


PbO dissolves in vinegar just fine, that's how the ancients did it, and that's what I did on my website.

PbO can be produced directly (although also as indicated on my website, the yield can be poor, resulting mostly in suboxide and lots of granular metal), but probably not PbO2.

Tim




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[*] posted on 18-7-2010 at 02:17


Hi, I have opened up a small lead-acid battery to see if I can find any easily extractable PbO2 and Pb metal. The battery was old and unable to crank much but prior to the dissection I gave this battery a good charge to concentrate the H2SO4 and to convert as much of the PbSO4 to PbO2.

The anode consisted of pressed brown PbO2 in a Pb grid which was housed between the cathodes in a plastic sheath which must be a porous membrane. Due to the damaged (old) state of the battery the Pb grid had collapsed and the plastic sheath held a mass of brown muck with pieces of Pb grid-no wonder it couldn’t hold a charge!!

My question is: how pure is the PbO2 and has anyone attempted to isolate it and obtain the usable PbO2. I would like to know if such recycling is worthwhile before I attempt this messy and potentially hazardous (many precautions taken) separation.

Also apparently the cathode consists of Pb sponge pressed into a Pb grid. These pressed pieces certainly rush to a grey powder in a pestle and mortar. Such finely divided metal would probably be more reactive which could perhaps facilitate the Pb + acetic acid preparation of lead acetate? One would have to consider the likelihood of antimony and other additives participating in this reaction.

Any thoughts welcome.

Barbs



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[*] posted on 24-7-2010 at 15:08


Has anyone had any success making lead tetroxide? I'm having troubles.
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[*] posted on 11-9-2011 at 09:42


Sorry to revive this old thread.

I want to make some lead (II) acetate (trihydrate) from scrap (battery) lead and acetic acid (I have glacial acetic so can prepare any concentration). I’ve trawled through the entire thread but little definitive is said on a workable recipe for the acetate.

Garage Chemist claimed success with dissolving lead in hot 25 % HAc, combined with 30 % peroxide (first page) but he wasn't very explicit. And someone else warned about over-oxidising the lead to lead (IV) acetate.

12AX7 (Tim) claims lead dissolves even in commercial vinegar but isn’t very specific either. That sound pretty slow to me, lead’s not hugely reactive…

Lead acetate does have a strong differential in hot/cold water solubilities, which should serve well for recrystallisation w/o boiling to dryness (not recommended with acetates anyroads).

Does this jog anyone’s memory on a prêt-a-porter recipe to fairly clean Pb(Ac)2.3H2O?




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[*] posted on 11-9-2011 at 13:43


If you want to use the route I did, ie, via PbO, you'll have to make the PbO first using KNO3. This can be done as I show here:

http://www.sciencemadness.org/talk/viewthread.php?tid=52&...

That red mud is surely PbO.




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[*] posted on 12-9-2011 at 06:46


Thanks Magpie, but I'm looking for something a little more direct.

For instance I've got lead nitrate, so I could e.g. go nitrate > carbonate > acetate but that seems such a waste of nitrate, if direct (and swift) dissolution of lead scrap in HAc + H2O2 is indeed feasible (as garage chemist suggests).

Guess I'll have to experiment, huh? ;)




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[*] posted on 12-9-2011 at 06:58


Don't even need H2O2, just bubble air through the acetic acid with the lead in that. The more surface air the lead has the better.
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[*] posted on 12-9-2011 at 07:04


Quote: Originally posted by not_important  
Don't even need H2O2, just bubble air through the acetic acid with the lead in that. The more surface air the lead has the better.


Yes, that was mentioned higher up but my (limited) experience with air oxygen as an oxidiser is that it's pretty slow. I used it once to oxidise Fe (II) in hot (80 C) acid solution and although it worked it took a long time to get to completion. Not highly practical from that perspective.

Worth a try though...




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[*] posted on 15-9-2011 at 10:44


Lead Acetate from battery lead, glacial acetic acid and hydrogen peroxide

I took some pictures of this experiment but due to a Blogger glitch I can’t upload. Maybe tomorrow…

A 58.3 g lead button (about 0.26 mol) was obtained as part of a defunct car battery electrode and cleaned up (a bit) with some sanding paper.

I then mixed 47 ml of water, 36 ml of glacial acetic acid and 26 ml of 35 % H2O2. This is the theoretical stoichiometric amount for:

Pb === > Pb2+ + 2 e
H2O2 + 2 H+ + 2 e === > 2 H2O
2 x [ HAc === > H+ + Ac- ]

Pb + 2 HAc + H2O2 === > PbAc2 + 2 H2O

And would yield (at 100 % yield and no losses) a saturated solution of PbAc2 at 40 C (sol. 116 g/100 g water, acc. Wiki). Of course this is ‘theory’ and nothing more than a starting point…

The lead button was then added (everything at RT) and reaction started immediately, with strong evolution of gas (oxygen? hydrogen?). The reactor (an oversized tall 1 l pyrex beaker with a cooled lid for reflux) was then moderately heated on an electrical hot plate.

After simmering away for about 35 min the reaction more or less died, and the solution/suspension was dark grey with plenty lead left. In total I revived the reaction about three times, each time by adding 10 ml HAc and 10 ml H2O2 and stopped after about a total time of 105 min. I then hot-filtered the grey solution/suspension on a #1 filter: it filtered easily to a clear solution. But there’s plenty metal left: visually I’d say only about half of the lead had actually dissolved. The left-over sludge, left mainly in the 1 l beaker, was subjected to the same treatment as described above and also filtered. But even after that second treatment grey-black sludge with pieces of lead are left!

One ml of the first filtrate was treated with KI solution and tested very strongly for lead: lots of yellow PbI2 precipitated. And after about 30 minutes when the PbI2 had precipitated to the bottom completely, some I2 could also be seen: oxidation of iodide by residual peroxide? Oxidation of iodide by Pb (IV)?

Both solutions are now being iced overnight but I somehow doubt I will obtain PbAc2.3H2O crystals because I think the solubility limit at 0 C (19.8 g/100 g water, acc. Wiki) will not be exceeded.

So far this has not been a ‘quick and dirty route’ to lead (II) acetate.

Does any one know the main contaminants in electrode lead? It seems harder than sheet lead e.g.


[Edited on 15-9-2011 by blogfast25]




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[*] posted on 15-9-2011 at 12:42


Quote: Originally posted by blogfast25  
Does any one know the main contaminants in electrode lead? It seems harder than sheet lead e.g.
Not sure about your sample in particular, but antimony is the most common lead hardener for alloys. There's likely some others in there, although likely not at higher percentages than Sb. I'd suspect As and Sn as well.

Arsenical alloys for batteries: http://www.keytometals.com/Article88.htm
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[*] posted on 15-9-2011 at 12:58


Quote: Originally posted by watson.fawkes  
Not sure about your sample in particular, but antimony is the most common lead hardener for alloys. There's likely some others in there, although likely not at higher percentages than Sb. I'd suspect As and Sn as well.

Arsenical alloys for batteries: http://www.keytometals.com/Article88.htm


Antimony: I thought as much. That would not dissolve in this mixture I think (but it may turn to oxide). Later on this week I’ll be dissolving the filter residues in aqua regia, that should roughly separate any Pb from Sn/Sb. Trouble is that the latter two aren’t easy to separate or test for with wet methods…

I was kind of surprised at the hardness of this lead: fairly though to hacksaw too…

Thanks for the link.

[Edited on 15-9-2011 by blogfast25]




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[*] posted on 15-9-2011 at 14:52



Be aware that the gas liberation will cause a mist of liquid to come out of the container (like a fizzy drink throws up droplets of itself out of a glass). This will be toxic. Put a cover on the beaker.

[Edited on 15-9-2011 by dann2]
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[*] posted on 16-9-2011 at 02:56


Quote: Originally posted by dann2  

Be aware that the gas liberation will cause a mist of liquid to come out of the container (like a fizzy drink throws up droplets of itself out of a glass). This will be toxic. Put a cover on the beaker.

[Edited on 15-9-2011 by dann2]


There was. As reported.




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[*] posted on 16-9-2011 at 06:08


Quote: Originally posted by watson.fawkes  
...Not sure about your sample in particular, but antimony is the most common lead hardener for alloys. There's likely some others in there, although likely not at higher percentages than Sb. I'd suspect As and Sn as well.

...


Calcium is not uncommon, especially in the smaller sealed batteries but apparently also in extended life automotive types as well.
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[*] posted on 16-9-2011 at 06:36


Quote: Originally posted by not_important  
Calcium is not uncommon, especially in the smaller sealed batteries but apparently also in extended life automotive types as well.


The alloys used for outer electrodes and pressed 'panels' may also be different. Sn/Sb/As affect charge retention, acc. Watson's link. Hardness is definitely more important for the exterior electrodes.

It'd be interesting to test acetic acid/H2O2 on a pure lead sample but I haven't got any. Lead shot, wheel balancing weights, fishing weights etc are all likely to be adulterated.

As expected no lead acetate crystals formed in the iced solutions, concentration being too low by a factor 2 to 4 I believe. But glistening smallish crystals can be seen on the dried filters...

[Edited on 16-9-2011 by blogfast25]




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[*] posted on 17-9-2011 at 09:30


Lead acetate update:

Below: the 54 g button of lead I started off with:



1. Crystallisation of the lead acetate:

The solutions of both tests above were combined, giving 272 g of solution which was first boiled down to about half the volume and then cooled. No crystals were obtained. Today I boiled it down further to 89 g of solution at which point it kind of had stopped boiling altogether. No turbidity developed. On cooling the mass congealed into a perfectly clear, stiff but jelly like substance:



This is likely to be a supersaturated solution or a supercooled liquid. I added 50 ml of DIW and dissolved the mass on the hot plate, then added a small amount of seed crystals (some lead acetate that had crystallised on a spatula). Within minutes crystals started to appear:



On cooling on ice, within minutes even more crystals were forming but I didn’t have time to take a shot.

2. Treatment of the filter residue with acids:

One part was treated with HNO3 38 %, another part with HNO3 38 % + HCl 37 % (aqua regia). In both cases the residue turned to a much lighter colour and some NO>NO2 developed.

With the nitric only, some white crystals of Pb(NO3)2 formed on cooling. The lighter colour of the residual nitric insoluble matter could point to SnO2 and/or Sb2O5, as both are highly insoluble.

With the aqua regia, plenty of PbCl2 precipitated on cooling. But the residue didn’t completely dissolve and a white mass was left: hard to say whether it was PbCl2 or the said Sn/Sb oxides or both and I didn’t attempt separation.

3. Aqua regia and the original lead alloy:

Determined to try and show presence of Sn or Sb, I tried to dissolve 25 g of the alloy in aqua regia (110 g HCl 37 % + 20 ml HNO3 70 % - this is a formula that works excellently for pewter). It worked surprisingly badly here. At RT there is slight attack, but at BP reaction is vigorous with loads of NO>NO2 evolved. But the lead alloy only dissolves slowly and after about 1 h the reaction died and most of the metal hadn’t dissolved. On cooling typical PbCl2 crystals formed but the quantity was well below what to expect from 25 g of lead (0.116 mol). It’s pointless to try and demonstrate Sn or Sb when so little alloy had dissolved. Tomorrow I’ll have another jab at it with strong HNO3…




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