Sciencemadness Discussion Board - Reduction of Arsenic Trioxide with Lithium

Reduction of Arsenic Trioxide with Lithium

Chemistry Alchemist - 25-8-2011 at 04:23

i have an old container of arsenic, i dont know what compound it is, but im highly sure it is Arsenic Trioxide. now ive done a reaction of lithium and Sodium Hydroxide, the Lithium reduced the Sodium Hydroxide to form Lithium Hydroxide and Sodium Metal (Li+NaOH=LiOH+Na), would the same thing be possible with reducing Arsenic Trioxide with lithium and then clean the arsenic with Cont. Hydrochloric Acid? im wanting to collect elements and unfortunately arsenic is on the periodic table and want it over and done with, please help, my friend is coming over in a few days and i wanna show the reduction of one of my chemicals to yield the element

mario840 - 25-8-2011 at 04:43

Why you make things so complicated ? just add your arsenic trioxide to hot 25% HCl , filter, and start adding SnCl2 in conc. HCl , stir and heat to little boil for couple minutes, very clean arsenic will be at the bottom of baker, wash with hot water, alcohol and then ether and dry.

2AsCl3 + 3SnCl2 ---->2 As + 3SnCl4

Chemistry Alchemist - 25-8-2011 at 04:54

yeah ill think about that, sounds like a good method, but i dont wanna work with heaps of arsenic salts, i kinda want to get it over and done with if u know what i mean...

Endimion17 - 25-8-2011 at 05:16

Quote: Originally posted by mario840

Why you make things so complicated ? just add your arsenic trioxide to hot 25% HCl , filter, and start adding SnCl2 in conc. HCl , stir and heat to little boil for couple minutes, very clean arsenic will be at the bottom of baker, wash with hot water, alcohol and then ether and dry.

2AsCl3 + 3SnCl2 ---->2 As + 3SnCl4

Arsenic trichloride is a nasty compound because it's volatile. It's not that easy to do such an experiment. You wrote it as it's a cookbook dealing with eggs and flour. What ever happened to stoichiometry? This is inorganic preparative experiment, not a demonstration.

Chemistry Alchemist - 25-8-2011 at 05:20

yeah thats what i was thinking, ive looked it up many times and it looks like a very bad salt of arsenic, thats why i suggested my method because it reduces it directly to As and ill just clean the As with HCl to get rid of the Lithium oxide

mario840 - 25-8-2011 at 05:31

hahahahha in this process you generate AsCl3 in situ and there is no need to purify this compound by destilation in matter of THAT fact it's like boiling egg, every person who dealing with arsenic compound i think is aware of dangerous and should have proper equpiment etc. etc. flask and condenser with ice cold water will do the job try to minimalize volatile of AsCl3 and then adding SnCl2 give very fast, very pure compund.

Chemistry Alchemist - 25-8-2011 at 05:54

so you reckon my way is a viable route to getting arsenic? may not be the purest way but its safer dealing with AsCl3

Mixell - 25-8-2011 at 05:58

I found this equation on Wikipedia:
H3AsO3(aq) + 3 H+ + 3 e− As(s) + 3 H2O E(V): +0.24

Arsenous acid is formed by slow hydrolysis of arsenic trioxide (should be faster in hot water with good stirring), so I think there is no need for an intermediate of AsCl3.

The reaction should be as follows:

2As(OH)3(aq) +6HCl +3SnCl2 ---> 2As(s) + 6H2O + 3SnCl4.

blogfast25 - 25-8-2011 at 06:28

Messing with arsenic????

You guys out of your collective minds? Someone who obviously knows precious little about chemistry should stay miles away from any arsenic compound. Unless of course you want to create a potentially lethal HAZMAT case for yourself and possibly die in the process.

Chemistry Alchemist - 25-8-2011 at 06:31

Quote: Originally posted by blogfast25

Messing with arsenic????

You guys out of your collective minds? Someone who obviously knows precious little about chemistry should stay miles away from any arsenic compound. Unless of course you want to create a potentially lethal HAZMAT case for yourself and possibly die in the process.

doing this under certain conditions, knowing the dangers, knowing what can happen and all that, im sure if we know all that, then we can maybe preform it saftly

blogfast25 - 25-8-2011 at 06:38

Quote: Originally posted by Chemistry Alchemist

Quote: Originally posted by blogfast25

doing this under certain conditions, knowing the dangers, knowing what can happen and all that, im sure if we know all that, then we can maybe preform it saftly

Yeah, make sure to pour some napalm on it too...

Nutcase.

Endimion17 - 25-8-2011 at 07:04

Well, the reaction can be done using minute quantities and is safe.

2H3AsO3 + 3SnCl42- + 6Cl- + 6H+ → 2As(s) +3SnCl62- + 6H2O
(it doesn't matter how you choose to write the first reactant)

If you don't have arsenic trioxide, you can use any alkali arsenite.

You get a brown powder. It's a classic experiment from analytical chemistry and it's done in a test tube by adding drops of aqueous arsenite solution in aqueous tin(II) chloride solution.
I have maybe a pinch of arsenic made this way.

The important thing is not to mess with it afterwards, like burning it outside of the fumehood, heating it in chlorine, etc.
Arsenic is one hell of a poison, so I really don't reccomend doing this if "you found this equation on teh interwebs".
Just let it stay in your element collection.

Does anyone know what kind of allotrope is this? It might be black, but fine powdered, therefore brownish.

Sedit - 25-8-2011 at 07:07

Quote: Originally posted by Chemistry Alchemist

doing this under certain conditions, knowing the dangers, knowing what can happen and all that, im sure if we know all that, then we can maybe preform it saftly

You don't know the dangers and im sure you can not do this safely. I'm not insulting you even though I really want to because I fear, from reading your last few post, that you are inches away from killing yourself. Your method sounds a lot LESS safe then the one offered to you in this thread because you will be dealing with a heated salt that will more then likely vaporize when the Lithium startes to catch fire. Now you will have an entire area down wind contaminated with the Arsenic salt you where to afraid to work with.... kid, buy what you need for your element collection this time because your gonna get hurt or someone else will.

zhaokenb - 25-8-2011 at 07:08

Quote: Originally posted by Endimion17

Quote: Originally posted by mario840

I think you could make a James Marsh reaction.
As2O3＋6Zn＋12HCl＝2AsH3＋6ZnCl2＋3H2O
and arsine isn't very durable.Arsine is gas in normal temperature,so you can make arsine go through the glass pipe,and heat the glass pipe up.Then arsine will decompose to creat arsenic and Hydrogen.
But arsine is very dangerous,so you need some defence equipment.

This way is much cheaper and easier.

[Edited on 25-8-2011 by zhaokenb]

Sedit - 25-8-2011 at 07:11

Should we speak out or just let Darwin work his magic?

Chemistry Alchemist - 25-8-2011 at 07:12

Quote: Originally posted by Sedit

Quote: Originally posted by Chemistry Alchemist

doing this under certain conditions, knowing the dangers, knowing what can happen and all that, im sure if we know all that, then we can maybe preform it saftly

Thanks for you concern, i do relies the dangers, im going to be doing this reaction in a closed vessel with 1 hole so any gas's produced will escape and will not explode, and ill make sure its not windy when i do it

Sedit - 25-8-2011 at 07:26

You don't understand, you should not do it at all.

The method provided for you is immeasurably safer and given that you do not see the dangers and/or short comings in your method means your a huge liability to yourself and those near you right now.

Bot0nist - 25-8-2011 at 07:27

"ill make sure its not windy when i do it"

Good, That way you may only kill yourself.

blogfast25 - 25-8-2011 at 08:03

Quote: Originally posted by Sedit

Should we speak out or just let Darwin work his magic?

Definitely another one intent on f*cking himself out of the genepool!

Relax, don't do it!

http://www.youtube.com/watch?v=yPLrXFw76Qg

And with the money spent on cracking open expensive virgin Li batteries you could probably buy a nice ampouled sample of pure As for your collection...

I strongly suggest also reading this SM thread, very related:

http://www.sciencemadness.org/talk/viewthread.php?tid=16067&...

[Edited on 25-8-2011 by blogfast25]

Endimion17 - 25-8-2011 at 08:16

Quote: Originally posted by zhaokenb

Marsh probe is for making arsenic mirror. It's for analytical, minute quantities and very impractical for any actual production.
The probe is used to show that a sample contains arsenic and not for getting arsenic.

Quote: Originally posted by Sedit

Should we speak out or just let Darwin work his magic?

It is ethical to speak. We are animals, but not just animals.

Quote: Originally posted by Chemistry Alchemist

Ummm, no. Just don't do it.

It should be windy, you should be upwind together with everyone and everything.
It's a messy reaction. Impractical and expensive. Spending elemental lithium instead of tin(II) chloride in hydrochloric acid solution? If you're that rich, you ought to buy arsenic. And a fumehood.

No, really. Dude, don't do it. If you want arsenic, use the wet tin method. Otherwise, you'd probably get severely hurt.

Chemistry Alchemist - 25-8-2011 at 08:23

yeah i dont know if its happening now, i just put a tiny sample in water to see if it dissolved and it didnt >< plus! its a light pink colour... not a white... but the label clearly says arsenic poison... you guys win... i guess u can all celebrate now.... illl just stick to the less toxic reductions

Mixell - 25-8-2011 at 08:38

All this talk about arsenic made me want to transfer my silicon to a transparent vessel, after that I did it with germanium...
And when I was trying to shove my nice 2.2g germanium crystal into the vial, it fell from hand and into the bushes bellow (I was doing it there because there was a bit of very very fine germanium powder that was prone to getting airborne).
Just wanted to share my "crappy incident of the day".
Searching for it yielded nothing, except for a few ants on my toes.

[Edited on 25-8-2011 by Mixell]

Bot0nist - 25-8-2011 at 09:15

Quote: Originally posted by Chemistry Alchemist

yeah i dont know if its happening now, i just put a tiny sample in water to see if it dissolved and it didnt >< plus! its a light pink colour... not a white... but the label clearly says arsenic poison... you guys win... i guess u can all celebrate now.... illl just stick to the less toxic reductions

You are the winner here if you don't do it. I know it seems like we were having a piss at your expense, but we were trying to prevent you from applying for a Darwin award. Tough love.

Now maybe you will be around for awhile to learn from, and contribute to SM.

MrHomeScientist - 25-8-2011 at 09:45

Amidst the chorus of "don't do its", I looked around a bit and found another possible method. It's actually the very first way it was made: "...discovery has been attributed to Albertus Magnus in 1250AD. He isolated arsenic when he heated soap and orpiment (arsenic trisulphide, As2S3)." (Source - also mentioned on the wiki)

So another method would be to convert the trioxide to the sulfide by heating it with sulfur:
2As2O3 + 7S → As4S4 + 3SO2 (speculated reaction path)
Then, react that with sodium hydroxide to form elemental As. (Source: Handbook of Inorganic Chemicals, Patnaik)

Of course, I agree with everybody else: don't do it. Arsenic is really too dangerous to mess with. The fully aqueous chloride method above is the safest option, but still quite dangerous. I just present this alternative for academic interest, and the interesting tidbit about its original discovery. The sulfide method adds the additional danger of SO2 of course, as if this needed to be any more dangerous.

Endimion17 - 25-8-2011 at 09:56

I guess this lady will have an extra hour off.

@MrHomeScientist: That is also messy, as elemental sulphur in almost all dry reactions tends to mess up the reaction mixture. That would require excess sulfur, mixing (too complicated) and time. Not to mention one has to heat up a vessel full of the nasty trioxide, which sublimes.

Buy yeah, from an academic standpoint, it's nice.

Chemistry Alchemist - 25-8-2011 at 09:57

Thanks MrHomeScientist, I've given up on it

not_important - 25-8-2011 at 20:03

Good chance you had lead arsenate. I bought some decades ago when it was still a common pesticide, and it was coloured pink and is practically insoluble.

Chemistry Alchemist - 25-8-2011 at 20:09

any way of separating the 2 SAFELY?

not_important - 26-8-2011 at 06:40

What does your use of the term "safely" mean? You're dealing with fairly toxic materials, safety depends on what precautions you take.

I used the stuff to make elemental As by mixing with powered wood charcoal, and heating in a retort make from steel pipe with the traditional condenser for As - a long tube formed of rolled up iron sheet. The Pb remained behind as the metal, while the Na ended up as carbonate.

A safer means might be to heat with aqueous Na2CO3, forming sodium arsenite solution and leaving the Pd as basic carbonates which can be filtered out (real filter paper, not coffee filters or paper towels. After that pick one of the aqueous based reductions, adding concentrated HCl and then SnCl2 would seem to be easy. But do some research on your own, download some o the older free chemistry books to be found as they often have preparative methods.

Chemistry Alchemist - 26-8-2011 at 09:50

safety as in the safest way with out killing anyone

Endimion17 - 26-8-2011 at 10:05

There is a whole spectrum of stuff that can happen between "nothing" and "killing someone". It involves chemical damage to the body.