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Author: Subject: The lead salts preparation thread!
kazaa81
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cool.gif posted on 12-3-2006 at 11:40
The lead salts preparation thread!


Hello,

I decided to create a thread about lead salts preparation, with the hope that everyone will help posting synthesis and preparations, so that we will make a pdf for the prepublications thread.

Here is a link of a zip containing tables extracted from Handbook of Chemistry and Physics, with lead salts properties:
Lead Salts properties.by.kazaa81
(thanks to my friend for hosting the file!)

So, lets start! :D

[Edited on 12-3-2006 by kazaa81]
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[*] posted on 12-3-2006 at 12:55


A few weeks ago I made a good sized quantity of lead acetate.
It was created by dissolving lead in a mixture of acetic acid (ca. 25% concentration) and H2O2.
The acetic acid must be present in considerable excess, since the mixture must never be allowed to become basic (the H2O2 would decompose violently and splash around the solution).

Lead sheet is added to an excess of 25% acetic acid, heated to nearly boiling and 30% H2O2 slowly dripped in, under constant stirring. The lead is dissolved rapidly, without gas evolution (only a very small amount of oxygen is generated).
The solution is then decanted, while still hot, from a small amount of undissolved lead and carefully evaporated in a warm place (don't boil the solution!), like on the heater in your room. A pleasant fragrance of acetic acid will fill the house during the process.

BTW, there is already a thread on this. Could someone merge this thread with it?
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[*] posted on 12-3-2006 at 22:50


a month or so ago after making litharge (lead oxide) as by product from sodium nitrate reduction, I added aqueous hydrochloric acid and the long needle white crystals formed were lead chloride.



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[*] posted on 12-3-2006 at 23:12


A while back I dissolved some shot in acetic acid and H2O2, filtered insolubles, and then added HCl. I wanted to make a lots of crystals of PbCl2, but I did not have the patience/balls to make large volumes of hot concentrated lead chloride solution(indoors). That and I used too much HCl so it was vaporizing while I was heating the solution.



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[*] posted on 13-3-2006 at 01:47


Lead hydroxide

Dissolve sodium or potassium nitrate, sodium chlorate or sodium perchlorate in water sufficient to make a conductive solution. (Potassium chlorate and sodium chloride also work, but KClO3 has low solubility and NaCl must be hot for this process to work; sodium acetate isn't a strong electrolyte.) Attach a bar of lead to a +5V supply and use any conductive material for the cathode (steel sheet, copper, graphite, titanium, etc.). Anode reaction: Pb = Pb(2+) + 2e- (lead dissolves into anolyte). Cathode reaction: 2H+ + 2e- = H2 (hydrogen ions are removed, causing a basic (excess of hydroxyl ions) catholyte). When solution mixes, hydroxide precipitates lead ions, forming white Pb(OH)2.

Some carbonate (as CO2 bubbled into the solution) can be added to produce lead carbonate (basic, I believe).

The process using chloride ions must be performed warm, else the lead ions will precipitate with chloride ions at the electrode, causing passivation and oxidation to brown PbO2.

Lead can also be heated in air and stirred (use ventilation!), but it does not produce much oxide; the product is essentially sand-sized lead droplets with a layer of suboxide (Pb2O) on the surface.

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[*] posted on 13-3-2006 at 05:30


Lead nitrate
I added 7 grams of lead shot to appr. 25 ml of 52% HNO3. The lead at first dissolves vigorously, but at the end, the reaction becomes very slow. Heating was needed to dissolve all of the lead in the acid. During the reaction, a white very fine crystalline precipitate of Pb(NO3)2 was formed. Be very careful at this stage. Lots of brown fumes of NO2 are formed and also fine droplets, containing lead (II) ions may be thrown into the air. Do this initial step outside or in a good fume hood.

I heated the solution carefully, until it almost was dry, with constant stirring to assure that no local hot spots are formed, where the lead nitrate decomposes.

The final drying was done by spreading the solid on a piece of glass and letting it dry in contact with warm air (e.g. a radiator will do). In summer, a hot dry place, also is suitable. After a few hours, a white crust and powder was obtained. The powder I have still is quite acidic, but I did not recrystallize it again. The acidity is advantageous with aqueous experiments (lead (II) tends to hydrolyse very easily), but for pyro-applications it certainly is not good at all.




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[*] posted on 13-3-2006 at 05:33


Thanks all for replying, any preparation welcomed!

I was thinking about electrolytical production of PbCl2...can one use lead as anode of a NaCl or HCl solution? The Cl- ions would combine with lead and form white PbCl2?

Also...from wikipedia:
"PbCl2 is used in synthesis of lead(IV) chloride (PbCl4): Cl2 is bubbled through a saturated solution of PbCl2 in aqueous NH4 forming [NH4]2[PbCl6]. The latter is reacted with cold concentrated sulfuric acid (H2SO4) forming PbCl4 as an oil."

If you don't know from what lead salt preparation start to post, just check the tables...there are plenty of lead salts and even more reactions to make them!


[Edited on 13-3-2006 by kazaa81]
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[*] posted on 13-3-2006 at 07:46


PbCl2 is easily prepared by dissolving lead in HCl of moderate strength, the reaction taking some time (few weeks). The reaction is faster when the HCl is heated.

When NaCl solution is electrolysed with two lead electrodes, mainly Pb(OH)2 is formed due to the OH- ions being formed at the cathode reacting with the initially produced PbCl2.
However, by stirring this Pb(OH)2 with HCl, PbCl2 is formed.

PbO2, lead dioxide, is very easily made by electrolyzing 20% H2SO4 with two lead electrodes. At the cathode hydrogen is evolved, at the anode PbO2 is formed as a dark brown powder.
The electrolysis can be continued until the entire anode is converted into PbO2. The PbO2 is isolated by filtering the solution, washing and drying the PbO2.

PbO2 is a powerful oxidiser, capable of forming very energetic pyrotechnic mixes, especially with powdered metals.
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[*] posted on 13-3-2006 at 10:07


Quote:
Originally posted by garage chemist
PbCl2 is easily prepared by dissolving lead in HCl of moderate strength, the reaction taking some time (few weeks). The reaction is faster when the HCl is heated.

When NaCl solution is electrolysed with two lead electrodes, mainly Pb(OH)2 is formed due to the OH- ions being formed at the cathode reacting with the initially produced PbCl2.
However, by stirring this Pb(OH)2 with HCl, PbCl2 is formed.

PbO2, lead dioxide, is very easily made by electrolyzing 20% H2SO4 with two lead electrodes. At the cathode hydrogen is evolved, at the anode PbO2 is formed as a dark brown powder.


As I mentioned, anodic corrosion of lead in NaCl leads to Pb(OH)2 when sufficiently hot, or a soft crust of PbCl2 and PbO2 when cooler. This is not a satisfactory method to produce PbCl2 or PbO2.

Anodization of lead in sulfuric acid leads to PbO2, as a crust. Some flakes off, but not much. This method does not produce useful amounts of PbO2, unfortunately.

The best method for PbCl2 is to oxidize the metal and then react with HCl. Direct reaction with HCl is slow (weeks) and/or painfully annoying (boiling HCl, my nose rejoices), or else wasteful of oxidizer (H2O2, etc.), though the latter depends if it's a concern of yours...

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[*] posted on 13-3-2006 at 13:01


What if one try to use lead anode and/or cathode in a strong HCl solution? Would be the production of PbCl2 better?
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[*] posted on 13-3-2006 at 14:03


Yes, lead anode in HCl should make PbCl2 in good amounts.

Although I don't know why you'd want PbCl2... its solubility is too low for it to be of real value.
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[*] posted on 13-3-2006 at 21:32


Well, you can't use acid because the metal plates across...

Even in concentrated HCl, hot enough to dissolve a reasonable amount of PbCl2, I doubt it'll hold too much before lead metal plates out. It's just not very reactive.

For synthesis you want Pb(NO3)2, true, but I like PbCl2 for its hot solubility and furry crystal texture. 8)

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[*] posted on 14-3-2006 at 00:14


The metal will plate across but if you preform the electrolysis in a manner completely unconducive towards electroplating you can dissolve the anode much faster then it will plate on the cathode. For instance I did electrolysis with nickel electrodes in HCl with 14 amps and 12 volts. The solution heated to boiling within a few mintues but before it could go any further what was left of the anode had broke off at the surface and the cathode only had some strange spires on it. I let it cool and repeated a few times and before I knew it I had a saturated solution of nickel chloride.

To get over the low rate of solvoylsis of Pb in HCl couldn't you just get an aquarium bubbler and bubble air into it? This would prove useful to make the acetate. One of the older methods involved hanging lead plates above a bath of acetic acid, the combination of the fumes and the air attacking the plates and the sugar of lead being scraped off periodically.




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[*] posted on 16-3-2006 at 05:41


Actually, I am leaving some pieces of Pb in 30% HCl, but as expected, the reaction is very slow, so slow that it can't be even imagined to be posted in the pdf we will make... :o
I am thinking about dissolving the "sponge" Pb made from NaCl electrolysis...
I will soon try electrolysis of Pb in HCl (maybe using only one Pb electrode) and reaction of Pb with Cl2...If someone can try something too, we will appreciate this!

[Edited on 16-3-2006 by kazaa81]
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[*] posted on 16-3-2006 at 07:24


Extract from "The Preparation of Pure Inorganic Substances", E. H. Archibald, Wiley, New York, 1932.

Its only 3 pdf pages, but such is my scanning skillz that its ~1Mb. Contains the preparation of pure lead, lead nitrate, lead chloride and lead bromide. If one, for whatever reason needed it "pure".

http://xfiles.ft100.net/images/pure_inorganic_substances-lea...
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[*] posted on 16-3-2006 at 10:34


Thank you Axt...I've searched some about this on Brauer "handbook of inorganic preps" but if you read in the lines...
"LEAD, PUREST FORM
Commercial electrolytic lead (about 99.995%) is sufficiently pure
for most laboratory purposes. However, it contains, depending on
the method used in its production, varying concentrations of minute
amounts of Cu, Bi, Fe, Zn, Cd, As, Sb, Sn, Se, Te and rare metals,
totaling about 5-50 • 10^-6 g. of impurities/g"

:o of course here we are claiming that 99.995% isn't enough pure for we!
I think you can understand these aren't really the preparations needed by an amateur chemist, and so, for our pdf.
I've an idea about how to structurate it (the pdf):
- A general part talking about lead and a table with lead salts properties
- A part concerning about how to change metallic Pb in soluble-salts Pb
- A last part concerning about methasynthesis of soluble-Pb-salts, because some of these are otherwise difficult to obtain without a methasynthesis.
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[*] posted on 22-5-2006 at 06:21
Lead Acetate


Am finally crystallizing some lead acetate today.

The solution is brown with, I presume, iron acetate, and probably some amount of copper acetate as well. This was obtained by reacting vinegar with my lead oxide, which has been produced variously by reacting lead with HCl and neutralizing the PbCl2; electrolyzing lead in a neutral chlorate or acetate solution; etc. The iron impurity is probably from the metal sheet I calcined the product on.

There is also some (probably basic) lead acetate now in solution, from the first product I made (which didn't crystallize very well).

The solution has gone from a gallon down to er.. maybe 16 ounces in a jar. Funny story, I stuck the syruppy liquid in the freezer to attempt to crystallize it. When it was cool, I came back and it was completely solid, even with the round crystallization fronts like when supersaturated sodium acetate is seeded into growth.

I have since melted the mess and it seems to be better behaved now. It is currently cooling to room temperature and forming mats of variably brown crystals, which I will filter, wash and recrystallize to, hopefully, a much happier white product...

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[*] posted on 27-5-2006 at 16:24


Question: does your lead acetate trihydrate typically clump?

My product is currently a crystalline/prismatic, free flowing powder with some clumps not broken up, but when left to sit in free air for a day or two it gets sticky and needs to be shaken to get it free again. It also smells of acetic acid.

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[*] posted on 27-5-2006 at 16:56
Lead Acetate


The credit for this procedure belongs to many people but I thought it worth mentioning.

Some copper carbonate(cheap from the pottery shop) is added slowly to hot vinegar and
stirred until no more CO2 is produced. Number 9 bird shot or any other suitable small lead
pieces is put into the solution. After a few days the lead will displace the copper ions and
the blue-green colour will disappear. Filter out the remaining lead and copper formed.

I prefer to keep the lead acetate in solution to plate PbO2 onto gouging rods.




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[*] posted on 30-5-2006 at 20:24




Recrystallized (once) lead acetate, still a yellowish tinge. Still caking up and smells. Haven't weighed it but probably around a pound. Still more to recrystallize and add to the pile.

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[*] posted on 10-12-2006 at 11:08


I had recently prepared some crystals of lead (II) acetate*3H20 using assay grade PbO, of which I have a supply good enough for several lifetimes. Then I got to making FeS (or attempting to) and needed to test my products to verify the synthesis. My method was to treat a few mg in a small test tube with 6N HCl then carefully waft a few vapors in my direction to check for H2S. I had heard of lead acetate papers being used in some of the old lab manuals for detecting H2S and was wishing I had some. So yesterday I made up a 5% aqueous solution of lead acetate*3H2O in an evaporating dish and soaked some 7cm filter papers in it. These were then hung up to dry overnight. Today I cut the papers into strips and tried them out on some H2S. They worked as you can see in the photo below:

lead acetate paper.jpg - 86kB




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[*] posted on 10-12-2006 at 12:02


I prepared lead acetate from Pb3O4 "was used in paint" and let it react with acetic acid over night at room temp. and I got very clear and colorless solution, then I recrystalized very nice crystals with no yellow or red color.
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[*] posted on 10-12-2006 at 12:43


Hey, did anyone get an insoluble salt while recrystallizing Lead acetate? I think it could be lead subacetate, but it wont dissolve in excess acetic acid either.



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[*] posted on 10-12-2006 at 13:46


Did you use tap water? Hell, even the "distilled" vinegar I have makes white junk (most likely sulfate or chloride) when lead ions are added. :(

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[*] posted on 10-12-2006 at 15:12


Quote:
Originally posted by 12AX7
Did you use tap water? Hell, even the "distilled" vinegar I have makes white junk (most likely sulfate or chloride) when lead ions are added. :(

Tim


I used Distilled Vinegar only. So its not the carbonate? Thats cool then, I can just filter it off then.




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