Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: Bill.D.Katt. on 25/04/2011 05:02:33

Title: Can barium chloride (BaCl2) be made from barium sulphate (BaSO4)?
Post by: Bill.D.Katt. on 25/04/2011 05:02:33

I've been wondering how I could make BaCl2 from BaSO4. Wikipedia states: "BaSO4 + 4 C → BaS + 4 CO" then "BaS + CaCl2 → BaCl2 + CaS" (http://en.wikipedia.org/wiki/Barium_chloride) It states that this is performed on an industrial scale, could this be done on a minor scale, and are there any other methods?

Title: Re: Can barium chloride (BaCl2) be made from barium sulphate (BaSO4)?
Post by: lightarrow on 25/04/2011 12:34:46

BaSO₄ + 2Al --activation energy--> Al₂O₃ + BaO + S

or, maybe:

3BaSO₄ + 8Al --activation energy--> 3Al₂O₃ + 3BaO + Al₂S₃.

Then you dissolve BaO with HCl. Al₂O₃ doesn't dissolve in it, Al₂S₃ forms, I think, AlCl₃ (soluble) and H₂S (very poisonous).

To favour the first reaction, I would use an excess of BaSO₄ with respect to Al. Furthermore, the reagents should be in powders mixed extremely well.

Title: Re: Can barium chloride (BaCl2) be made from barium sulphate (BaSO4)?
Post by: Bill.D.Katt. on 26/04/2011 05:05:18

Oh, wow. That was an energetic reaction. Not as bright as thermite, but hot enough to burn through the steel pan it was on. So I just throw the powdery stuff left over into some HCl? Once it has fully reacted to AlCl3 and BaCl2 do I force it out of solution by fractional crystallization (after evaporating off excess HCl)? Or can I through a base into solution and only precipitate out one species?

Title: Re: Can barium chloride (BaCl2) be made from barium sulphate (BaSO4)?
Post by: lightarrow on 26/04/2011 16:42:21

Quote from: Bill.D.Katt. on 26/04/2011 05:05:18

Oh, wow. That was an energetic reaction. Not as bright as thermite, but hot enough to burn through the steel pan it was on.

I hope you used an excess of sulphate as I said, otherwise I think it is, as or more bright than thermite...

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So I just throw the powdery stuff left over into some HCl?

Yes, you should first disgregate it in powder if it's in greater pieces. Then I would use diluted HCl (it's enough to react with BaO and it's not enough to react with Al₂O₃).

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Once it has fully reacted to AlCl3 and BaCl2 do I force it out of solution by fractional crystallization (after evaporating off excess HCl)? Or can I through a base into solution and only precipitate out one species?

Better the second: Al(OH)₃ precipitates just from pH > 4. At pH = 6 is completely precipitated. You can increase pH up to 9; for pH > 9 the Al(OH)₃ begins to dissolve as alluminate, so I would adjust the pH to ~ 7. Ba(OH)₂ is soluble so you don't have the problem of this precipitate.