Sciencemadness Discussion Board

aluminium sulphate to h2so4

Little_Ghost_again - 22-10-2014 at 14:34

Is it possible to make sulfuric acid from aluminum sulphate?
I know you can make aluminum sulphate from sulphuric acid but wondered if you could reverse this somehow and make sulphuric acid from aluminium sulphate

Metacelsus - 22-10-2014 at 17:27

Not easily. I'm not sure, but you might be able to drive off sulfur oxides from aluminum sulfate if you get it hot enough, and make sulfuric acid that way.

Oscilllator - 22-10-2014 at 19:10

Perhaps precipitating aluminium oxalate with oxalic acid may yield some results, but it's only an idea.

Oxirane - 23-10-2014 at 04:46

The compound decomposes to γ−alumina and sulfur trioxide when heated between 580 and 900 °C. (source=wikipedia)

In practice you would want to use 50-70% sulfuric acid that is cooled in a bath to bubble the SO3 through it. In theory you should get 3 mols of H2SO4 from 1 mol of Al2(SO4)3.

blogfast25 - 23-10-2014 at 05:41

Quote: Originally posted by Oscilllator  
Perhaps precipitating aluminium oxalate with oxalic acid may yield some results, but it's only an idea.


In dilute solutions that probably works but then you get very dilute H2SO4. In more concentrated solutions Al oxalate will remain somewhat soluble.

More promising would be displacement with phosphoric acid, because Al phosphate is very insoluble. But who would want to sacrifice H3PO4 for H2SO4?

Tidbit from Atomistry:

"When aluminium hydroxide is dissolved in hot, concentrated aqueous solutions of the alkali acid oxalates and the solutions allowed to cool, crystalline double or complex oxalates are obtained of the type M3Al(C2O4)3.xH2O."

Dilute H2SO4 would be the by-product.

http://aluminium.atomistry.com/aluminium_oxalate.html

vmelkon - 24-10-2014 at 11:05

Why not just buy drain cleaner? Some stores sell 90 to 98% H2SO4 but some of them add an organic coloring.
Or get old car batteries.

For you case, (decomp Al2(SO4)3), you would need a metal can and a copper tube and the heat of a fireplace will easily reach 700 °C.

ValenceOctet - 24-10-2014 at 12:08

Quote: Originally posted by vmelkon  
Why not just buy drain cleaner? Some stores sell 90 to 98% H2SO4 but some of them add an organic coloring.
Or get old car batteries.

For you case, (decomp Al2(SO4)3), you would need a metal can and a copper tube and the heat of a fireplace will easily reach 700 °C.


What drain cleaner is 98% pure H2SO4? :o




[Edited on 24-10-2014 by ValenceOctet]

Metacelsus - 24-10-2014 at 15:10

Rooto is around 96% (varies from batch to batch).

Little_Ghost_again - 25-10-2014 at 00:29

Its hard to get sulphuric acid around here. I have no near shops that sell it and internet dosnt always ship to Scotland.
I didnt think it would be easy, I have some copper sulphate so might make weak acid with that, then conc it then bubble in SO3. Bit of a faff. Just for some acid but not too many choices, I cant bloody get sodium free dishwasher tablets anywhere near here! And Mag Sulphate is proving hard to find without loads of other junk in it. phosphoric acid I can get easy from farm shop!

Oxirane - 25-10-2014 at 02:53

Quote: Originally posted by Cheddite Cheese  
Rooto is around 96% (varies from batch to batch).


We're not all living in America, my cheesy friend. :P

I have found drain cleaners that contain H2SO4 but I could not believe when I saw the price. I leave it for you to imagine but it was at least three-fold compared to extra pure lab grade ones per liter. Aluminium sulfate is sold at much lower rate, although it must be noted that it can be sold as hydrate which just doubles the molecular weight. Pure Al2(SO4)3 contains 84% in weight of sulfate so it is almost quantitive in weight per sulfuric acid in theory.

Little_Ghost_again - 25-10-2014 at 03:14

Its anhydrous. Yeah I found some drain cleaner in Glasgow but like you said ££££££

hyfalcon - 25-10-2014 at 03:57

Quote: Originally posted by Little_Ghost_again  
Mag Sulphate is proving hard to find without loads of other junk in it.


You can't get Epsom Salts from the drug store or farm store?

blogfast25 - 25-10-2014 at 04:57

Quote: Originally posted by Little_Ghost_again  
Its anhydrous. Yeah I found some drain cleaner in Glasgow but like you said ££££££


Really? Here about £5 for 1 L. Hardware store round the corner. Mine is dyed a vivid red though but for many applications that hardly matters.

Epsom Salt from the same shop, about the same price and very clean, clear crystals. Also from garden centres.

[Edited on 25-10-2014 by blogfast25]

aga - 25-10-2014 at 11:19

Do you specifically Need sulphuric acid ?

Perhaps some other acid(s) would be useable, and more easily available where you live.

Is there a reaction you have in mind ?

Little_Ghost_again - 25-10-2014 at 15:29

M problem is nearest big town is a city! Glasgow or 140 miles round trip, not much around me. Farm shop is bulk buy, so I can get 1 metric ton ammonium nitrate for £135, but fucking 1 Litre drain cleaner is 140 miles and £25. Mag sulphate again by the metric ton and not used much here, the farm lime with calcium because of the peat.

blogfast25 - 26-10-2014 at 06:25

There are various eBay sellers that will sell reasonable amounts of these chemicals for reasonable prices and with shipping to the farthest corners of Albion.

Little_Ghost_again - 27-10-2014 at 03:48

Except Scotland! The problem we have is very slightly different rules to England, so no one is really sure what rules apply with shipping. actually its unfair as we are under less restrictions, live north of Glasgow and the double shipping!
Have you seen the number of ebay sellers that have dropped off now for chemicals? Last I looked there were 3 maybe 4 that sold acid.

Amos - 27-10-2014 at 03:53

Quote: Originally posted by blogfast25  

More promising would be displacement with phosphoric acid, because Al phosphate is very insoluble. But who would want to sacrifice H3PO4 for H2SO4?



Would the sulfuric acid not just react with the salt of a weaker acid to turn it back into phosphoric acid and alumininum sulfate? And as far as finding phosphoric acid, not sure where you're from, but I found a gallon of it at Home Depot or Lowes for $15.

blogfast25 - 27-10-2014 at 05:53

Quote: Originally posted by No Tears Only Dreams Now  

Would the sulfuric acid not just react with the salt of a weaker acid to turn it back into phosphoric acid and alumininum sulfate? And as far as finding phosphoric acid, not sure where you're from, but I found a gallon of it at Home Depot or Lowes for $15.


Not if the solubility product of AlPO4 (Ks = 6.3 x 10<sup>-19</sup>;) is low enough and the formed sulphuric acid is not too strong.

But aluminium phosphate would probably dissolve in very strong sulphuric acid.

[Edited on 27-10-2014 by blogfast25]

Amos - 27-10-2014 at 06:25

Quote: Originally posted by blogfast25  
Quote: Originally posted by No Tears Only Dreams Now  

Would the sulfuric acid not just react with the salt of a weaker acid to turn it back into phosphoric acid and alumininum sulfate? And as far as finding phosphoric acid, not sure where you're from, but I found a gallon of it at Home Depot or Lowes for $15.


Not if the solubility product of AlPO4 (Ks = 6.3 x 10<sup>-19</sup>;) is low enough and the formed sulphuric acid is not too strong.

But aluminium phosphate would probably dissolve in very strong sulphuric acid.

[Edited on 27-10-2014 by blogfast25]


Yeah, there's going to be some kind of equilibrium that would be established. Seems like it'd be terribly difficult to purify and concentrate sulfuric acid made this way.