Arsenic Extraction From Realgar

[olmpiad]

YAAAY 20,001 post. Anyway, I typed this up the other day but I wanted to make sure that everything was accurate, is it?

 

 

As Extraction From Realgar

David Aldridge

 

Arsenic can be won from realgar by reacting the powdered mineral with Fe filings. The result will be solid As, and solid FeS. This needs to be done under a hood, as some of the As is vaporised into Arsine.

 

Fe: 1 Mole is equal to 55.847 g

As: 1 Mole is equal to 74.92159g

S : 1 Mole is equal to 32.066 g

 

If we break up everything into 1/10th of a mole for each of the elements (The As and the S are still attatched, we are just figuring out how much of each element is present), we would find that 1/10th of a mole of each would equal...

 

55.847g Fe = 5.6g Fe

74.921g As = 7.5g As

32.066g S = 3.1g S

 

Thus, the approxamite amount of each chemical that woud be needed it as follows...

 

10.8g AsS

05.6g Fe

 

In The End, we would obtain...

 

8.9g FeS

5.6g As

 

The equation for this reaction would be as follows...

 

AsS(s) + Fe(s) --> FeS(s) + As(s)

 

 

 

©2006 by David Aldridge

[ecoli]

I think you mean 20,001 threads.

[olmpiad]

oops, sorry about that

[woelen]

IIRC, Realgar is not AsS, but As2S3:

 

http://webexhibits.org/pigments/indiv/technical/realgar.html

 

The reaction will be As2S3 + 3Fe ---> 2As + 3FeS

 

Now you could redo you molar computations again.

 

If you really want to do this in practice (???), then be EXTREMELY careful. Arsenic is very very toxic and it is among the most toxic elements. It also is a carcinogen. Without proper lab stuff, this is insanely dangerous to perform.

[olmpiad]

IIRC' date=' Realgar is not AsS, but As2S3:

 

http://webexhibits.org/pigments/indiv/technical/realgar.html

 

The reaction will be As2S3 + 3Fe ---> 2As + 3FeS

 

Now you could redo you molar computations again.

 

If you really want to do this in practice (???), then be EXTREMELY careful. Arsenic is very very toxic and it is among the most toxic elements. It also is a carcinogen. Without proper lab stuff, this is insanely dangerous to perform.[/quote']

 

Actually, Realgar is AsS. As2S3 is the mineral Orpiment. Here are the references...

 

Acta Crystallographica: 5: 775-782.

 

Zeitschrift für Kristallographie: 136: 48-65.

 

American Mineralogist (1972): 57: 524.

 

Kyono, A., Kimata, M. & Hatta, T. (2005): Light-induced degradation dynamics in realgar: In situ structural investigation using single-crystal X-ray diffraction study and X-ray photoelectron spectroscopy. American Mineralogist 90, 1563-1570.

 

Realgar does turn to orpiment over time if it is exposed to air and light, however, pure realgar is indeed AsS.

[woelen]

Hey, nice to see that. I always thought it was As2S3. I've indeed done a google on arsenic sulfide and realgar in Google (without the quotes) and one of the pages is this:

 

http://www.galleries.com/minerals/sulfides/realgar/realgar.htm

 

It confirms what you say, it is As4S4, which of course has empiric formula AsS. Always nice to learn new things .

[olmpiad]

Yep, learning is fun. Realgar is one of those minerals that fools a lot of people. Orpiment and Realgar almost always occur together so the formulas are often confused.