Sciencemadness Discussion Board

Another beginner question - lead (II) acetate

keithakers - 25-8-2018 at 07:06

I was preparing lead (II) acetate with metallic lead, vinegar, and h2o2. Since all I have available is OTC concentrations, I removed some of the solution into another vessel to evaporate in the oven while I added more to the original to continue reacting the remaining lead and put the 2nd container in the oven at around 250-300 f to evaporate.

Eventually it seemed most of the lead had reacted in the first container so I also put it in the oven to help speed the reaction. Some of the lead acetate definitely came over into the 2nd container because the compound had precipitated out before I pipetted it over.

I left it over night in the oven to evaporate at around 250 F. When I checked in the morning, it seems most of the lead in the original container had finished reacting (good) but the second had dried and then bubbled up and turned brown.

I'm wondering what I this brown substance is. I tried dissolving it in more vinegar and it doesn't seem very soluble. I filtered it with a coffee filter (I'm too broke to buy real equipment at the moment) and the filtrate is a brown liquid and a grayish brown substance has been left on the filter. I'm not sure if the filtraye is brown because whatever it is is soluble or if the particulate size is too small to be filtered by a coffee filter (I think probably the latter).

I've searched and tried to figure out what it might've turned into but I'm not sure. I've found at a certain temp lead acetate decomposes but I believe I kept it under that temp.

Any ideas on what I made? Some sort of lead oxide?

I know this probably has a simple answer, but we've all got to start somewhere after all.

By the way, my end goal here is again for pyrotechnics- lead tetraoxide (acetate to carbonate to tetraoxide) but I like keeping a bit of the compounds I make along the way in case I have need of them in the future.

[Edited on 25-8-2018 by keithakers]

CobaltChloride - 25-8-2018 at 07:29

The brown stuff is most likely burnt sugar from the vinegar. Vinegar has some sugars dissolved.

On another note, I hope that the oven used during these procedures isn't also used for food. Please be careful of cross contamination.

keithakers - 25-8-2018 at 07:43

I will admit it is used for food, but I'm very careful of spills and do not plan on working with it for very long as I will be able to purchase equipment soon. As long as there are no spills then there should be no contamination correct?

Also, if the brown stuff was sugar, shouldn't there be nothing left on the filter as it should dissolve? I will try rinsing the filter with hot water to see if anything happens. Thanks for your response!

Edit: Nearly boiling water did not dissolve the substance in the filter- the filtrate came out clear

[Edited on 25-8-2018 by keithakers]

CobaltChloride - 25-8-2018 at 08:05

You might just have formed some caramel which doesn't dissolve all that easily.

If the solution reached the boiling point in the oven, then a fine mist of lead salt containing particles could've settled on all the surfaces inside. It doesn't matter that you were careful in all other steps if the solution fizzed at any point during its time in the oven. I would personally stop eating food prepared in that oven if this were the case.

Corrosive Joeseph - 25-8-2018 at 08:24

Quote: Originally posted by keithakers  
I will admit it is used for food


Lead compounds are horribly toxic.........
https://en.wikipedia.org/wiki/Lead_poisoning

Please think about this if your loved ones eat out of that oven.



/CJ

keithakers - 25-8-2018 at 08:27

It probably did reach a light boil at some point considering the temp I set it out...looks like I'm cleaning my oven today. Though I'd doubt that the amount of lead sprayed into my oven would be high I have a respirator/goggles/gloves etc.

And I'll be evaporating with air for the rest of this. I know lead is dangerous, and I use PPE whenever dealing with it, I had just made (apparently wrong) assumption that the amount that would get into my oven would be miniscule.

[Edited on 25-8-2018 by keithakers]

fusso - 25-8-2018 at 08:28

You used the kitchen oven to heat/boil lead solution?! Congratufuckinglations! You've ruined the oven for everyone who will be cooking with that! :P

[Edited on 25/08/18 by fusso]

keithakers - 25-8-2018 at 08:33

Quote: Originally posted by fusso  
You used the kitchen oven to heat/boil lead solution?! Congratufuckinglations! You've ruined the oven for everyone who will be cooking with that! :P

[Edited on 25/08/18 by fusso]


Alright I get, don't follow my my example I fucked up.

fusso - 25-8-2018 at 08:47

Quote: Originally posted by keithakers  
Quote: Originally posted by fusso  
You used the kitchen oven to heat/boil lead solution?! Congratufuckinglations! You've ruined the oven for everyone who will be cooking with that! :P

[Edited on 25/08/18 by fusso]


Alright I get, don't follow my my example I fucked up.
You should notify everyone living in your house immediately to never use that oven to prepare food again.

[Edited on 25/08/18 by fusso]

Deathunter88 - 25-8-2018 at 08:50

Ignoring the fact that you have also likely coated the heating elements with a film of lead which will now slowly evaporate lead vapors as you make food, it's a good idea to refrain from heating/boiling to dryness salts of acetic acid and nitric acid, as they tend to decompose or form insoluble basic forms of the salt. A better way would be to evaporate most of the water at room temperature, then if the salt is very hygroscopic, put it into a ziploc bag with some silica gel or sodium hydroxide.

JJay - 25-8-2018 at 08:52

You can buy toaster ovens at thrift stores for around $10. Given a choice between paying $10 and organ failure, I'll take $10 every time!

keithakers - 25-8-2018 at 09:10

Quote: Originally posted by fusso  
Quote: Originally posted by keithakers  
Quote: Originally posted by fusso  
You used the kitchen oven to heat/boil lead solution?! Congratufuckinglations! You've ruined the oven for everyone who will be cooking with that! :P

[Edited on 25/08/18 by fusso]


Alright I get, don't follow my my example I fucked up.
You should notify everyone living in your house immediately to never use that oven to prepare food again.

[Edited on 25/08/18 by fusso]


Well I live by myself so that should be fairly easy

@JJay thanks I will definitely follow that advice for now on as I do enjoy having working organs

[Edited on 25-8-2018 by keithakers]

RogueRose - 25-8-2018 at 10:15

The brown is often a result when using food vinegar, even white distilled. I wondered if it possibly could be Pb2O3 or some other lead oxide. I had a hard time following the procedure you described but it seems like you heated to evaporate and when it got to the syrup'y state (melted hydrate form) this is probably when it started to get brown, is that correct?

There are a couple options and I don't remember what I did - you should search my username for my thread on lead acetate - I'm too tired to do that now - very long day.

I do recall filtering it through activated carbon and I had to powder it, turn it into almost a dust, then added some to the solution and shook the mixture and then stirred for a while - followed by filtering a few times to remove all the carbon (it is slow, but use the same filter as the carbon filters out the smaller pieces each time it passes through). I believe this was the best method for removing the color as I got pure white crystals of trihydrate and anhydrous.

If you go for anhydrous, do it slowly and cover it with aluminum foil (it may react if it touches the foil) with a few holes poked in to let vapor come out. You should stir it and break up the chunks as it dries b/c if you don't you will get a very hard brick of acetate which is a major PITA to break up, so do it before it turns into a brick stuck on the evaporating dish.

I also found that when going for anhydrous I still sometimes get a slight tan tint when it is a crystal, but if it is powdered, it turns pure white. I think this might be a characteristic of the compound but I do know that the carbon filtration makes a big difference.

If the carbon filter doesn't do it, then you have some oxides (was it done in a steel pan? Could it be Fe2O3?? I believe hot peracetic acid can react with steel and stainless steel though I can't remember). If there is Pb2O3 then you will need to add more acid and H2O2 and heat to mild heat (~120-140) and allow to sit for a few hours. Having excess acid and H2O2 when going to either filter or evaporate, seems to give a cleaner, whiter product. I think when making copper acetate you need to have excess acetic acid while boiling off water or you will end up with CuO and maybe Cu(OH)2 so maybe lead has a similar reaction - so adding some extra acetic acid before evaporating might be a good idea, but make sure to filter it through activated carbon (AC) first

I know some people will say that the AC shouldn't remove the sugars like this, but I can attest that it does for certain. I had the same problem with sodium acetate, I had a brown/orange color crystal before I filtered it with AC, then I got a pure white product.

Good luck & let us know how you make out.

BTW, what lead did you use? What was the source?

AJKOER - 25-8-2018 at 14:04

A possible idea to decontaminate surfaces!

Get proper safety gear and using disposal paper towels clean all areas possibly contaminated with a film of Pb salt with an excess of a NaOH based spray oven cleaner. Follow safety instructions.

Chemistry:

PbAc2 + 2 NaOH (aq) = Pb(OH)2 (s) + 2 NaAc

2 NaOH (aq) + Pb(OH)2 (s) = Na2[Pb(OH)4] (aq)

Link: https://chemiday.com/en/reaction/3-1-0-240

Repeat cleaning exercise....

Children are generally more sensitive to Pb, so they should leave....

Adults with heavy metal exposure should consult a physician! Also, ask about EDTA, available as an over the counter heavy metal chelator (note, EDTA has been approved by the FDA for heavy metal chelation).

[Edited on 25-8-2018 by AJKOER]

fusso - 25-8-2018 at 14:18

Quote: Originally posted by AJKOER  
A possible idea to decontaminate surfaces!

Get proper safety gear and using disposal paper towels clean all areas possibly contaminated with a film of Pb salt with an excess of a NaOH based spray oven cleaner. Follow safety instructions.

Chemistry:

PbAc2 + 2 NaOH (aq) = Pb(OH)2 (s) + 2 NaAc

2 NaOH (aq) + Pb(OH)2 (s) = Na2[Pb(OH)4] (aq)

Link: https://chemiday.com/en/reaction/3-1-0-240

Repeat cleaning exercise....

Children are generally more sensitive to Pb, so they should leave....

Adults with heavy metal exposure should consult a physician! Also, ask about EDTA, available as an over the counter heavy metal chelator (note, EDTA has been approved by the FDA for heavy metal chelation).

[Edited on 25-8-2018 by AJKOER]
Then why not just use NaOH solution?

AJKOER - 25-8-2018 at 14:45

Fusso:

I suspect one needs a spray to properly cover all surfaces and a foam to pickup the insoluble Pb(OH)2 from say a first light spray application, which is all cleaned up with disposable wipes.

Follow up with a second light spray and a final application of perhaps a heavy dose possibly forming the soluble Na2[Pb(OH)4].

Not an expert on Lead decontamination, but an attempt, with safety gear, is, in my opinion, likely better than doing nothing assuming that the contamination is not spread (hence disposable wipes). Also, converting the acetate to the more insoluble Pb(OH)2 should decrease, but certainly not eliminate, toxicity concerns.

[Edited on 25-8-2018 by AJKOER]

RogueRose - 25-8-2018 at 18:35

What about just washing with dilute H2SO4. you'd get lead sulfate which isn't soluble in water or acetic acid. IDK if MgSO4 solution would work as well as you would get lead sulfate again and Mg acetate which shouldn't be harmful and can be washed away with the PbSO4.

another thought is oxalic acid or sulfamic acid solutions which might give lead oxalate or lead sulfate.

What do you think?

AJKOER - 25-8-2018 at 19:32

Quote: Originally posted by RogueRose  
What about just washing with dilute H2SO4. you'd get lead sulfate which isn't soluble in water or acetic acid. IDK if MgSO4 solution would work as well as you would get lead sulfate again and Mg acetate which shouldn't be harmful and can be washed away with the PbSO4.

another thought is oxalic acid or sulfamic acid solutions which might give lead oxalate or lead sulfate.

What do you think?


Between a strong base or a weak acid, I would select the strong NaOH.

H2C2O4 will also work but its salts are also considered toxic.