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Author: Subject: Making Lead Nitrate
aga
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[*] posted on 23-6-2014 at 10:57
Making Lead Nitrate


Lead Nitrate was one of today's 'Make This' compounds, as the stuff to make it was at hand.

So,
Pb(s) + 4HNO3(aq) -> Pb(NO3)2(s) + 2NO2(g) + 2H2O(l)

The Lead was a 10g solid chunk of lead, used as a ballast weight in a model airplane.
The Nitric acid was 6.8[M]and an excess of 30% was added over the stoichiometric quantity required.

Pretty orange gas evolved.

What i ended up with was a grey-white precipitate, with some (about 10%) unreacted metal, which was a surprise.

Reading that Lead Nitrate is soluble in water, i decanted the liquid from the reaction beaker, leaving mainly the grey/white precipitate, then added 100ml of water.
The precipitate refuses to dissolve.

What i get is a milky liquid, with most of the grey-white powder remaining as a solid.

Is it obvious to anyone where i went wrong ?




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Zyklon-A
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[*] posted on 23-6-2014 at 11:18


Lead impurities are the only things that come to mind.
Are you sure of the purity? It likely contains antimony, tin and other impurities if it was just a weight.
Either way, it's probably possible to use the solution you have, as it should be reasonably pure lead nitrate (aq).
Two recrystallizations should do the trick.




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aga
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[*] posted on 23-6-2014 at 11:20


ahhh. so the precipitate is SOS* and the lead nitrate is still in solution !

Obvious ! Doh ! Well, obvious now.

So i'll filter out the SOS and boil down the liquid.

Many thanks.

*Some Other Sh1t

[Edited on 23-6-2014 by aga]




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blogfast25
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[*] posted on 23-6-2014 at 12:37


Careful boiling in lead bearing liquors: avoid things getting airborne with an hourglass (or similar) on the beaker. Lead (II) salts are very poisonous.

The state symbols (s), (g) etc are not usually written as suffixes. Just plain old Pb (s) will do...




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aga
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[*] posted on 23-6-2014 at 12:50


I will be careful.
Fume hood, fan over the beaker, as low a heat as possible to remove the water.

Sub tags are a pain to put in, so i just left the (s) etc as subscript.

Edit : Which is right ?

1. NH3(aq)
2. NH3(aq)

You mean #2 right ? Do it non-subscripted ?


[Edited on 23-6-2014 by aga]




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jock88
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[*] posted on 23-6-2014 at 14:22



Had a similar problem. The SOS I think is Tin Oxide.
The 'Lead' sheet may be old and contain Tin. The Tin is worth a few bob.

How would you be sure if it is Tin Oxide?
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[*] posted on 23-6-2014 at 16:53


After filtering and getting a clear solution you could add nitric acid to it. The nitrate precipitates out of solution and you can filter out. Give it a few washes with cold Ethanol (to clean excess acid) and let it dry. It's the safest way to make dry Lead (II) Nitrate. No eating required.
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[*] posted on 23-6-2014 at 23:01


Well I'd suggest not eating lead compounds. Checking for tin oxide is not so easy. Here's an old journal entry that might help: http://pubs.acs.org/doi/abs/10.1021/ja02042a009



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[*] posted on 24-6-2014 at 00:38



Guys,it is too complicated and maybe all of you are right.The lead it self can form lead oxides in nitric acid(I mean PbO that has 2 colors and PbO2) like dissolving Fe in nitric acid that forms iron oxides and just a tiny amount of iron go to the solution and make ferric nitrate(this problem contains nitrate of Pb/Fe/Hg/Bi/Sn/Ag/and some other elements)

For this problem I read somewhere to use a special procedure that I have
forgotten but I think he was using a certain concentration and density of nitric acid:o

I don't think so if it has Sb or Sn impurities.because they are valuable enough to not
use in toys and lead has a easy procedure for purifying.

I suggest you guys to use mixture of acetic acid and hydrogen peroxide to make

soluble lead acetate instead of using nitric acid.

Nitric acid has more difficult chemistery.in solutions with different concentration it
behaves differently.It's not just a simple acid like HCl,it is more complicated

Industry production of lead nitrate involves treating of lead oxide and nitric acid,or
treating its ores with nitric and subsequent crystalization.

I have same problem with mecury that I have dissolved its orange oxide in nitric acid and got a white precipitate.and I don't know what is this white material(maybe mercury(I)nitrate).I should use acetic acid and hydrogen peroxide but it is too late and mercury have a high price in Iran:D
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aga
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[*] posted on 24-6-2014 at 01:54


Seems that some of the SOS is PbO judging by the colour and wiki image.



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HgDinis25
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[*] posted on 24-6-2014 at 02:33


If you used excess Nitric Acid there is no room for PbO formation. Many Lead alloys have Tin that reacts wit Nitric Acid to form Tin Dioxide (insoluble).
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MrHomeScientist
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[*] posted on 24-6-2014 at 10:34


Yes, aga, non-subscripted for the state.
Lead is almost always alloyed with something to improve its mechanical properties - it's too soft to be useful for much of anything as the pure metal. Lead fishing sinkers are alloyed with antimony, so I'd expect your lead weight to also have some additives.
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[*] posted on 24-6-2014 at 10:39


In bags of those small crimp weights (I think that's what they're called, they're the tiniest size of lead weight) I have sometimes found individual weights made out of tin. It's a rarity, but it just goes to show that they aren't inspected for purity. (Tin itself needs to be alloyed to prevent the alpha form from destroying the weights.)



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[*] posted on 24-6-2014 at 10:45


When I made lead nitrate last year not everything dissolved. It's pretty common for lead to be alloyed with other stuff. Just filter it out.



As below, so above.
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[*] posted on 24-6-2014 at 10:51


@Sasan:

What MrHomeScientist said. For real applications Pb needs to be alloyed for strength. Sb is a very common lead hardener. There are others. For battery lead I've even read about Ca as a hardener.

And I can confirm from experience that pure lead (> 99 %) dissolves in nitric acid quite easily and completely.

Lead acetate from lead, GAA and peroxide is no sinecure either: once the peroxide has been used up/depleted too much the reactions stop. You need to keep topping up with peroxide, much of which get wasted in side reactions. I've done this and it ain't easy.

[Edited on 24-6-2014 by blogfast25]




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aga
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[*] posted on 24-6-2014 at 11:20


Well, i filtered, got a clear liquid, then started boiling.

At 50% original volume there were many shiny white glistening crystals on the bottom of the beaker.

So i got greedy and boiled down to 10%.
Now there is just white powder that will not dissolve in water.

Bugger.




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[*] posted on 24-6-2014 at 11:29


Quote: Originally posted by aga  
Well, i filtered, got a clear liquid, then started boiling.

At 50% original volume there were many shiny white glistening crystals on the bottom of the beaker.

So i got greedy and boiled down to 10%.
Now there is just white powder that will not dissolve in water.

Bugger.


Chances are that you've hydrolysed it, greedypants!

Not to worry: add a 'good dollop' of nitric acid and some water and gently heat with stirring to about boiling: the hydrolysate should redissolve but it could take some time. Add a bit more NA to dissolve the last stubborn bits.

Then allow it too cool and see if you get crystals. Lead nitrate has a strong solubility - temperature dependence, so boiling dry wasn't necessary: thermal recrystallization would force most of the lead nitrate out of solution anyway, after having evaporated say 50 % of the water.

http://en.wikipedia.org/wiki/Solubility_table#L





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[*] posted on 24-6-2014 at 11:36


Quote: Originally posted by blogfast25  
Chances are that you've hydrolysed it, greedypants!

Not to worry: add a 'good dollop' of nitric acid and some water and gently heat with stirring to about boiling

Yay ! Cheers for that. I will give it a go.
Dollops away !

Thanks also for the Solubility table link.
I've been looking up each substance individually and then trying to find the solubility data in the blurb.




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[*] posted on 24-6-2014 at 12:19


Don't forget the Lead Salts Preparation thread.

http://www.sciencemadness.org/talk/viewthread.php?tid=5490
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[*] posted on 24-6-2014 at 12:29


Thanks for the Lead Salts Preparation link.

Next time i will know what search terms to use !

Edit:
@blogfast25 : that worked. Thanks !

[Edited on 25-6-2014 by aga]




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[*] posted on 25-6-2014 at 11:22


One more thing:

Quote:
then added 100ml of water.
...
What i get is a milky liquid, with most of the grey-white powder remaining as a solid.


You used plain tap water, didn't you? The milkyness is due to a finely divided precipitate formed from the lead and carbonate/sulphate/phosphates/etc in tap water.

You should definately use deionized or distilled water when working with lead salts.
Solutions of silver salts also give a similar precipitate when mixed with tap water.

[Edited on 25-6-2014 by phlogiston]




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[*] posted on 25-6-2014 at 11:45


Nope.
I use Distilled De-ionised water in all things.

As soon as i threw the empty used beaker in the wash bucket, it turned the whole bucket of tap water milky white.

Amazingly i also have Silver Nitrate experiments on the go at the same time, and yes, they do the same to the tap water.

The milkiness in the lead nitrate beaker was lead oxide/hydroxide or similar, formed because i was greedy and tried to boil the liquid too far.

Edit: i should have mentioned that the solution had a stirbar running in it at the time.

[Edited on 25-6-2014 by aga]




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[*] posted on 25-6-2014 at 12:01


as i just some time ago decided to get my lead and copper back from one of my lead acetate 'cells' (Pb + CuAcetate) i had to decant it off a few times
to remove lead i reacted the liquid with NaHCO3 to get PbCO3
i decided to make Pb(NO3)2 from this
the solution seemed very cloudy, although there was excess HNO3 in it, and it was all totally dissolved
the salt of this then turned somewhat greenish when heated, heating it more removed all colour, strange.

i actually also recall some strange precipitate when i was making Pb(NO3)2 from HNO3 and Pb, but i think i managed to dissolve it.. if a solution goes cloudy you can add some acid to it, add too much and you will have a problem when you boil it away, though..




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
http://www.trimen.pl/witek/calculators/stezenia.html
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[*] posted on 29-6-2014 at 12:58


No HNO3, try starting with NH3, H2O2, and PbCO3. Now, per Atomistry.com, from an intermediate, Lead nitrite (see http://lead.atomistry.com/lead_nitrites.html ) to the nitrate to quote:

"Lead nitrite solution slowly decomposes thus:

3Pb(NO2)2 + 2H2O = Pb(NO3)2 + 2Pb(OH)2 + 4NO

a decomposition similar to that which nitrous acid itself undergoes"

I would assume one could treat Lead carbonate with Nitrous acid as a path to Lead nitrite:

PbCO3 + 2 HNO2 ---) H2O + CO2 (g) + Pb(NO2)2

Per Atomistry.com on Nitrous acid ( http://nitrogen.atomistry.com/nitrous_acid.html ), one of many paths to Nitrous acid to quote:

"Oxidation of ammonia with hydrogen peroxide produces nitrous acid, but there is always some ammonium nitrite present in the solution:

NH3 + 3H2O2 = HNO2 + 4H2O"

[Edited on 29-6-2014 by AJKOER]
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[*] posted on 29-6-2014 at 14:24


Er, Jokey A ?

The Lead Nitrate is already crystallised and in a jar, happily awaiting its next adventure.

Assume nothing, do the maths and do experiments.
Tends to work out as more fun, and more reactants !

Do you get your kicks out of randomly Googling chem stuff in order to respond to someone actually Doing some chemistry, or is it a Kick just to get some random chemist (as in an Actual Chemist) responding to to the stuff you've just googled ?

What is with the ammonia gig anyway ?
It's a chemical, yes, loosely bridging OC and IOC (in my mind at least), but nothing more.

Chemistry, to me, is Exploring the Theoretical, then Testing by Experiment.
Not Einstein's cheapskate Thought Experiments, but by Actual Experiments, to see what Actually happens.

You seem to be fixated on doing No experiments, and simply Googling to elcit any kind of response.

Brother or Sister, you are missing out on so so much, and appear to be learning less than i have in the past 3 months.




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