Epsom Salt -> Sulfuric Acid?

[Unsunghero]

Ok, so I discovered today that Epsom salt is essentially pure MgSO4...if this reaction would work it seems like it'd be a cheap way to produce H2SO4, whereas purifying battery acid or something along those lines can be expensive. Epsom salt is sold by the pound, HCl by the gallon...

I was wondering if the following reaction would work:
MgSO4 + HCl --> H2SO4 + MgCl2
To me this seems pretty likely because solubility rules don't apply to solids so SO4 wouldn't be soluble.

The only thing that concerns me is that I know Mg + HCl yields MgCl2 + H2...would the H2 combine with the sulfate? I can't think of anything else happening...

The only other thing I could thing of would be like
MgSO4 + HCl --> H2 + Cl2 + Mg
which would be useful at least for magnesium...you'd just have to keep away from it.

[fluoroantimonic]

Sadly, this will never work.. HCl is far more volatile compared to H2SO4. When you mix MgSO4 and HCl will get you a mixture of of H+, Mg++, SO4--, and Cl- ions. If you try to isolate H2SO4, say by boiling off the water to make MgCl2 crystallize out, you'll only end up boiling off the HCl.
Learn some more about basic chemistry.
There's a reason people buy drain cleaner or battery acid, it's pretty much the only way to get H2SO4 without a lot of trouble.

[iHME]

You can get some H2SO4 from MgSO4, by electrolysis.
In some process in "Kings chemistry survival guide" H2SO4 is produced as a waste product.
But any real production using this method would be ridiculously inefficient.

[Microtek]

If you had the equipment and experience for it, then it should be possible to first dehydrate the MgSO4 and then heat it further to cause it to thermally decompose to MgO and SO3 (I don't know how much SO2 you would get from 2 SO3 --> 2 SO2 + O2), then cool and absorb the SO3 in concentrated H2SO4 to make oleum and then dilute this (carefully) with water.

[fluoroantimonic]

thermally decompose to MgO and SO3

That would work in theory, but it would be massive waste of time and effort, MgSO4 decomposes pretty high as sulfates go, >1000*C meaning you would probably get >95% SO2.. Better to use NaHSO4.

[Bugger]

It just might be possible to do it metathetically if one could find a water-soluble acid (other than carbonic acid), which forms a very insoluble Mg salt, and of which the Mg salt (unlike carbonate) would not be decomposed or hydrolysed by aqueous H2SO4. Phosphoric acid might just work, at fairly low H2SO4 concentrations, but then it is probably too valuable for other purposes to be used just to obtain H2SO4.

[megalomania]

By direct chemical solution this is not possible, but by electrolysis it is. I have done just this while making magnesium hydroxide. Sulfuric acid forms at the other electrode in a divided cell. It took a very long time to get very little, and this is a terrible way of making magnesium oxides. Then all you end up with is some sulfuric acid contaminated with magnesium sulfate. It is not easy to purify that.

Far better to heat a mixture of sodium bicarbonate and magnesium sulfate in solution. This precipitates magnesium hydroxide while leaving sodium sulfate in solution. Sodium sulfate can then be decomposed into sulfur oxides far more readily than magnesium sulfate. I suppose if you could form iron sulfate from this mess you could directly decompose the solid into sulfuric acid like they did in the old days. This would involve checking some E degree or delta G tables to see which element sends the reaction in the correct direction (if it can even be done, I don’t remember off hand). This is old world 19th century chemistry here; the old science books would have a lot more detailed info on doing this.