Sulphuric Acid Synthesis

[evilgecko]

I'm trying to make sulphuric acid using only suphur, potassium nitrate and water. All the H's, S's, and O's are there, that hard part is getting them in the right order. Thanks to axehandle (Sciencemadness board) for this idea, you burn sulphur and potassium nitrate in a closed enviroment with water present. Most of you will know that sulphur burns to produce sulphur dioxide, which needs to be converted to sulphur trioxide before dissoving in water, otherwise it will form sulpurous acid instead of sulphuric.

 

The NO2 actually catalyises the reaction of SO2 to SO3 in the air, and then the SO3 is dissolved in water.

 

I used a 75L rubbish bin as my closed enviroment. I filled the bottom with 2L of water and put a little inverted container on the water. Then I made a mixture of 60% sulphur/40% potassium nitrate. And put about five grams in a small metal container on top of the inverted plastic one (plastic resists the acidic water and the metal one resists the heat produced). Then the mixture is lit and the lid closed. The mixture burns slowly, releasing SO2 and NO2 into the air. I leave it overnight and then repeat. By morning only a faint smell is left.

 

I repeated this for a week and now I hope I'm left with a mixture of sulphourous and sulphuric acid.

 

Is there anyway of destroying the sulphourous acid? I want to be able to measure the concentration of the sulphuric acid and hopefully concentrate it.

[Mumbles]

UV light converts sulfurous acid to sulfuric acid. Just sitting also converts it. Boiling the solution will also help. Sulfurous acid is not very stable. Leaving it be will give you sulfuric.

[delta_echo]

I have to ask: Why? Just for fun or the challenge? I mean, if you're looking for a supply of H2SO4, they sell it as drain cleaner around here. At, worst, take an old car battery, extract the acid, and then boil (outside) to concentrate. Of course, if thats not the case, have a good time, I guess.

[evilgecko]

Ok so since I'm concentrating it anyway the sulphous acid should be destroyed. No its not for fun trust me I'd rather be building fireworks. There is no such thing as OTC H2SO4 over here trust me I've checked everywhere. Only people who can prove they have legimate reason to use it for their buisness can buy it (like a cleaner etc).

 

I'm trying to work out how much H2SO4 would be produced per gram of sulphur burnt. Assuming that it gets completely converted and no losses take place. Then I'll work out a sensible percentage and compare it to the real result for help if I do it in the future. I'm thinking maybe 10% will be converted? There are lots of losses, such as sulphur not being fully oxidised, escaping rubbish bin, and then not fully dissolving.

[aquaman]

Delta_echo-

Where do you live because where I live (IL) there is no H2SO4 drain cleaners any more. There used to be but for some reason there is no hardware store, grocery store, or pool supply that carry ~95% H2SO4. The best I could find was 1/2 a liter of 10% at lowes in the pool section.

[Draco_Aster]

If you had a large vessel with a vaccuum you could speed up the process greatly. But I dont think this is going to happen with a garbage can Maybe heating the garbage can up a bit?? This might speed the process up?

 

REMEMBER - Chemical reactions occur when molecules collide. (so speed the bastards up!)

[Rogue Chemist]

Perhaps adding some V2O5 into the KNO3/S8 mix would increase the sulfuric acid content as more SO3 would be produced. Not sure how V2O5 would behave with that mix of chems, but it might be worth trying.

[evilgecko]

If I had precious V2O5 I wouldn't be burning it up in a rubbish can. Rather I would use the contact process as used in the industry where they pass SO2 gas over heated V2O5 in a tube.

 

Heating the rubbish bin up would be hard. I though maybe if I spray the water into the atmosphere in bin. I havn't worked out how to do this though because I'm scared that the acidic conditions would eat up my water pump.

[delta_echo]

Delta_echo-

Where do you live because where I live (IL) there is no H2SO4 drain cleaners any more. There used to be but for some reason there is no hardware store, grocery store, or pool supply that carry ~95% H2SO4. The best I could find was 1/2 a liter of 10% at lowes in the pool section.

I live in AZ (US). They have 95% H2SO4 at every ACE hardware store that I've been to. A liter for a few dollars. No luck with Home Depot, however. Haven't checked Lowes. I've never heard of pool suppliers carrying it as they usually just stick with HCl.

[evilgecko]

Ok, I took the liquid out of the rubbish bin and evaported the water of by boiling it in a beaker. I started with 1000mL and stopped when it was 100mL. The end solution has and orange tinge (I think that is from the pottery boiling chips rubbing against other). But there was also white kinda fluffy crystals left in the bottom of the beaker??? I don't know what this is. I don't think the SO2, NO2 reations produce any solids, so it must be contaimination from somewhere. There are quite alot of them to.

 

Measured denisty was 1.175, meaning it would be a 25% solution of H2SO4. But that dissolved solid would bump up the density too. And since I boiled it down to 1/10, that meant there was a 2.5% H2SO4 solution in the bin. Next time I'm going to burn way more sulphur before I concentrate, evaporating all that water is pointless.

 

Is there anyway of removing the substance? I can freeze down to -18C (or whatever higher temp if starts to freeze at) and filter if that would help.

 

Grrr how do I resize?

 

 

changed to just a link. That is quite a large pic. To resize, you have to use a program, the forum will not automatically do it for you. -Mumbles

 

Shit, when I removed the attachment, it seems it deleted it permenantly. I hope he has another copy

 

Found out i had photoshop on my computer and used that to resize...sorry Mumbles

[Rogue Chemist]

A guess is that it could be potassium sulfate from K2O from the combustion of the mix reacting with your sulfuric making K2SO4.

No V2O5? It's not too hard to get ahold of from pottery suppliers.

[evilgecko]

Well actually I have got a source of V2O5 its the equipment I don't have. Like the glass tubes and acid-proof condeser. This way is easy as well! The solution is quite viscous, is this normal for 25% acid?

[Draco_Aster]

ACTUALLY.....Maybe its best not to heat it up. According to 'Mellors Modern Inorganic Chemistry' it would be best to cool down the water as much as possible. Snow? You might even want to try freezing off the water to cencentrate the end product. I have a graph on the freezing points of H2SO4 on my computer somewhere.

[evilgecko]

Well the first attempt didn't go well. I boiled down the litre untill I had 10mL left and was starting to emit acidic fumes. I let it cool and but a drop on sugar, hoping it would be concentrated enough to turn it into carbon. After that didn't work I put a little nail in. It vizzed for about 5 mins and then stopped. The nail wasn't gone.

 

So it can't of been that concentrated. And since I removed 100 times the water it must of been very dilute to start with. I'm going to try again, this time proberly using up 200g of sulphur altogether.

[alyks]

I read in PMJB that you can make sulfuric acid by passing the burning sulfur fumes through calcium chloride to purify it, then by passing it through a mixture of asbestos and Iron (III) Oxide (mix rust with wet asbestos, dry) to oxidize to SO3. Is this true? If so, why isn't it well known?

[Douchermann]

Hmm, couldn't you theoretically make fuming sulfuric acid using this process? Just put 98% sulfuric acid instead of water and repeat the whole lead chamber process with sulfur and KNO3.