Diy H2SO4

[weknowpyro]

I know alot of people own highly concentrated sulphuric acid already (including myself) but i thought i would share my method of making a diluted sulphuric acid from limited chemicals, also please share your ideas.

 

You will need:

 

5g sulphur powder.

 

40ml distilled water.

 

Syringe (something to bubble oxygen through the solution).

 

2 test tubes.

 

Tongs.

 

Pour the sulphur powder into a test tube and then get the other test tube and reverse it so it is resting on top of the first test tube and secure it in place with tape or anything else.

It should look like this: http://www.apcforum.net/files/PICT0337.JPG

 

Next hold the test tubes using a pair of tongs and use a heat source to melt the sulphur into a liquid (I used a camp stove) it should now be producing a yellow gas - sulphur monoxide SO.

The gas should hopefully be making its way into the top test tube. So keep the test tubes in the flame for aslong as possible to collect enough gas.

Once enough has been collected turn off the heat source and start to take off the tape that is holding the two test tubes together. As soon as the top test tube is free put a bung in the top as quick as possible.

 

The next step is slightly hard, you have to add the water to the test tube without losing to much gas. Once this has been completed you will need to bubble the oxygen O2 through the solution.

Get the syringe and fill it with air and bubble this through the solution, i repeated this about 12 times.

After this just filter out your solution and throw away the solid.

This should be now a dilute form of tetroxosulphuric acid.

I tested my solution with litmus it was around p.h 3.

http://www.apcforum.net/files/PICT0336.JPG

 

Equation:

 

S(s) +(heat) -------> SO(g)

 

SO(g) + H2O(l) -----> H2SO2(aq)

 

H2SO2(aq) + O2(g) --------> H2SO4(aq)

[pudidotdk]

Sounds kinda easy, but the step about "adding water to the testtube" is somewhat unclear for me. Do you just put the testtube down in in some water so water comes up the test tube like you do when making HCl?

[weknowpyro]

Well all i did was to take the bung off the test tube and pour the water in by hand. This isn't exactly efficent because alot of Sulphur monoxide is lost whilst I did this. I expect anyway will work aslong as you add water into the same test tube as the gas.

[Mumbles]

If thats what you think is happening, you need to learn some more chemistry. Try on these reactions for size. They should cover everything you observed. I can guarantee you have no SO, or H2SO2.

 

S + O2 ---> SO2 Main reaction

2 SO ---> SO2 + S What happens to any SO actually formed

S (s or l) ---> S (g) The yellowish tint to the gas

SO2 + H2O ---> H2SO3 The actual initial acid formed

2 H2SO3 + O2 ---> 2 H2SO4 Converting it to sulfuric acid

3 H2SO3 ---> 2 H2SO4 + H2O + S A second reaction that happens accounting for the sulfur deposition, as well as the sulfur vapor condensing

 

 

Might I add that you have roughly 5x10^-4M H2SO4. Acidic rain water is usually around 10x as acidic as that. Why not just bubble the gas formed from the burning sulfur into water?

 

Another thing to look into is on science madness. A mixture of Sulfur and potassium nitrate, possibly some charcoal is mixed together and ignited in a closed container. The container has some water on the bottom, and the burning container, tuna can generally I believe, suspended above on a block of wood or glass. The sulfur di and trioxide formed dissolves slowly in the water below.

[weknowpyro]

Opp's, ok thanks for solving that mistake. The only reason I thought i had sulphur monoxide instead of sulphur dioxide is because when i was looking over the equations, I thought by adding oxygen to sulphurous acid i would form peroxysulphuric acid because i was adding 2 oxygen atoms to the existing three, i had not thought about by-products.

But my mistake, so thanks for correcting.

[Mumbles]

Peroxysulfuric acid is more commonly known as pirahna fluid. It's a mix of sulfuric acid and hydrogen peroxide. Mainly used as a cleaning agent. Oxygen itself doesn't really form peroxide bonds easily.

 

It's not a big deal, I just figured you'd like to more accuratly know what was happening.

[durfeedog]

 

Why not just bubble the gas formed from the burning sulfur into water?

 

I have a lot of sulfur about 150 lbs. Is this the best way to make SA on a laboratory scale from sulfur ? If not what is the best way to make SA from raw sulfur..

[asilentbob]

I have been reading about this kinda thing for a while now.

 

There is some great info at SMDB, especially in the article on SO3 and oleum.

 

When sulfur is burned, IE not simply heated, but really burned SO2 is formed. Passing it into water gives H2SO3, but not very readily based on solubility IIRC. SO2 to SO3 in the open air doesn't happen very readily. SO2 to SO3 at high temp and/or high pressure over V2O5/substrate or whatever catalyst happens much more readily. NOx is a catalyst for SO2 to SO3, but this doesn't work too well either.

 

SO3 + H2O is a very exothermic reaction. Some sources say that adding SO3 to straight H2O causes an explosion as it pretty much flash boils the H2O. Also SO3 will ignite things like wood. Nasty stuff.

 

H2SO4 + SO3 is much more manageable... Then the H2S2O7 that is formed is diluted with H2O forming 2 mols of H2SO4 from every mol of H2S2O7. Though generally they don't pump enough SO3 into the H2SO4 to make solid H2S2O7, just a solution of SO3 in H2SO4.

 

SO3/H2S2O7 have other possible uses. Both are fantasticly powerful dehydrators. Acetic anhydride production comes to mind.

 

SO2 + HNO3 ---> H2SO4 + NOx

Or something like that is a possibility. I can't remember if nitrogen oxides are expelled or stay in solution... if they stayed around you could dilute the mix with H2O and distill off the majority of the HNO3 (recycling it), then boil concentrate the H2SO4... Could be wrong somewhere screwing up the whole thing though...

 

Edit: Completely forgot to add:

The general way of preparing SO3 on a lab scale is the pyrosulfate way...

 

"Sulfur trioxide can be prepared in the laboratory by the two-stage pyrolysis of sodium bisulfate:

 

1) dehydration

2NaHSO4 → Na2S2O7 + H2O @ 315°C

2) cracking

Na2S2O7 → Na2SO4 + SO3 @ 460°C

 

This method will work for other metal bisulfates, the controlling factor being the stability of the intermediate pyrosulfate salt."

-wikipedia on sulfur trioxide

 

Sodium bisulfate is sold at pool supplies as a dry acid. It can also be used in many synths in place of H2SO4.

 

NaOH + H2SO4 → NaHSO4 + H2O

In that ratio atleast.

NaCl + H2SO4 → NaHSO4 + HCl

If you have some particular use for HCl gas... Now HBr or HI on the other hand... lol j/k... but there are very legit uses for both.