MgSO4 --> H2SO4

AHHH!!!! STUPID NO SUBJECT THING!!! I have to retype it all now!!! I spent 1/2 hour typing that!!!!

Anyways....

There seems to be a "sulfuric acid production race" going on here, with axehandle and his catalyst + burner, darkflame with his copper sulfate and me with electrolysis of MgSO4 (yes, im still working on that. Im a stubborn girl). I think I should start a new thread on this, because the old Copper Sulfate one was getting messy and deviating away from CuSO4

I attempted again to separate MgSO4 into H2SO4 and Mg(OH)2. I finally got some *real* carbon rods from D cells (not using those crappy pencil leads anymore ) and I replaced the papertowel salt bridge with a pvc tube to reduce all possibilities of contamination. A 30% (by wieght) MgSO4 solution was divided evenly into 2 containers and connected by the pvc tube and electrolyzed over night.

I woke up this morning and found that the anolyte was orange/amber AGAIN!! The catholyte seemed to be coming out ok like Mg(OH)2 was forming. Last time, this happened, we assumed it was iron. But this time, I am absolutely sure there was no ferrous materials in the cell. I had only glass containers, a pvc tube, carbon rods and solder (tin+lead) wires connected to the rods. I even wrapped the wired parts of the rods in tape to keep them dry. The wires also did not look corroded at all.







The only possibility of contamination would be from the solder wires I guess. I suppose I could try using copper wires hooked up the same way and see if the solution goes blue/green.

I am extremely confused now. Im not as into getting my H2SO4 now than I am in to finding out what this mysterious contaminant is. Its bugging the crap outta me!! Unfortunately, I do not have any NaOH, so I can't mix it with the anolyte to test for iron

Any ideas?

Edit: Filling a salt bridge is a REAL PAIN!!


Edit2: Stupid Tripod.....

[Edited on 25-3-2004 by Saerynide]

[Edited on 25-3-2004 by Saerynide]

If it is the solder, you could do as I did when trying to electrolyse FeSO4:

Have the connection wires be normal copper wires, stripped about 10mm, going to the electrodes through pvc tubes that barely slip over the end of the carbon rod, holding the copper wire firmly against the carbon rod as well as providing an airtight seal.

I'm sorry I don't have any pictures, I dismantled the electrodes after my spectacular failure (using a KNO3 based saltbridge made of paper towel pumping full bridge rectified mains 220V at ~10A through the towel, setting it on fire...)

PM me if you don't get what I mean and I'll draw you a picture, it's kind of hard to explain.

Edit: Pssssst...: This is a cleaner way of connecting the ATX PSU, it allows you to use multiple cells and higher currents (forces you to cut off the ATX mobo connector though):




Edit: Found the anode! Lousy pic quality, but:




[Edited on 2004-3-24 by axehandle]

[Edited on 2004-3-24 by axehandle]

[Edited on 2004-3-24 by axehandle]

[Edited on 2004-3-24 by axehandle]

Yeah I filled the pvc tube with the same solution in the jars.

Im out of baking soda now. I guess I'll try to run out at get some later today. To test for iron, I think I'll add vinegar to a bit of the solution and see if I get red insoluble ferric acetate. <-- Merk index is so useful

This idea is soooo good. Anyway, i was with my separation of two soluble salts(CuSO₄ and magnesium ethanoate)

I am going to try this out too as and when i have free time. The problem right now is that i cannot find graphite rods. Chemicals and equipment are pretty limited in Singapore. All we have is a homefix store and a pharmacy that caters to our health. I have got two choices: get carbon rods from batteries or buy those kind of charcoal drawing pencils, and try to get the leads out(i dun'y really know how )

As for the steel cathode, i am hoping to use a stainless steel bowl and connect this to wire. Is it ok to do so?


I also intend to do the flower pot method during the June holidays. Instead of using lead cathodes, can i use steel or carbon?

oh ya, Saerynide, could you post the pics again? The pics dun seem to be able to load correctly

[Edited on 25-3-2004 by darkflame89]

I tried charcoal pencils. They disintegrated really fast under high current or high voltage So I went for batteries. They seem to hold quite well (so far).

Yeah you can use carbon instead of lead, unless there's some strange mystical power of lead that I dont know of Stainless steel works too.

As for your stainless steel bowl, that sounds like a very good idea. I think Ill try it on my next run Thanks.

Ok, I tried adding vinegar with no luck I did not get any precipitate at all. Maybe it's because the H2SO4 in there keeps the ferric acetate dissolved, preventing it from precipitating?

Im heading out now on bike to get some baking soda to test the strength of the acid.

[Edited on 26-3-2004 by Saerynide]

Ok. i bought my box of Epsom salts. I am so happy. Also bought 2 D batteries so that i can get the carbon electrodes.

Anyway, your brown solution looked like Fe(OH)3 to me...

Edit: Ok, not iron hydroxide as it is insoluble. Maybe some other iron (III) compunds..

[Edited on 26-3-2004 by darkflame89]

Fe(OH)3 is insoluble in water. I think it looks like FeCl3.

I highly doubt it FeCl3 though, the only anion in there should be SO4-, unless... the tap water was *that* impure?? (I used tap water on this try because I didnt feel like wasting dH2O on the first test run )

I wrapped them with clear mover's tape, but don't do that - it doesnt work too well. I suggest several layers of rubber electricians tape instead. I used that under water a few times and it kept stuff dry

I still havent gotten around to building my plastic-tube protected anode yet. I'll try doing it tonight and get something posted by tomorrow

Cl2 precense in the tap water.

Wow, Im not half bad at recognizing common chemicals Hehehehehe...

Thanks for those suggestions. They really helped put all the pieces together

Anyways, tomorow morning, I'll do the second run,with distilled water instead and with my new protected electrodes (if theyre dry by then).

If there's still any contamination... then, I'll be damned and its coming from the MgSO4

Must head to bed now, its 3:40 am

Quote:

Originally posted by Saerynide Ok, I tried adding vinegar with no luck I did not get any precipitate at all. Maybe it's because the H2SO4 in there keeps the ferric acetate dissolved, preventing it from precipitating?

Those dont give you back what you typed They just reload the page.



[Edited on 27-3-2004 by Saerynide]

Oh! Mine gives me back what I typed. Mabe its because I use OPERA?

Browser Cache

Blah! I have silicone all over my hands from doing the final sealing on my protected electrodes, so im typing with 3 fingers and its hard

I added the baking soda to the contaminated solution til slightly over saturation, it fizzed alot (there is H2SO4 ) but, I got no iron carbonate precipitate. The excess soda sat at the bottom, and the solution stayed brown, but it got lighter in colour + murkier.

I just checked the Merck index, and it says that ferrous carbonate is soluble in CO2 saturated water..... So maybe there was FeCO3,but it stayed dissolved? I didnt know this before, so i dumped the whole thing down the fscking drain instead of leaving it to settle out!!!!

Now we'll never know, and it's all my fault

OK, I need to sort this out; I'm new to electrochemistry, and i feel that electrolysis has a lot of potential to produce all kinds of acids, bases, and salts that i need.

In this case, at the cathode side, H+ ions and Mg2+ ions are present in the water. Mg(OH)2 is formed because of the discharge of hydrogen gas. Which leaves the hydroxide ions behind. This then reacts with the magnesium ions to form Mg(OH)2. At the anode side, the copper anode(if i use one) will dissolve to form copper sulphate. Correct??

Therefore, in such a setup, i can produce a base or alkali at the cathose side, and produce salt(if i use a active electrode) or acid(if i use a inert electrode) at the anode. Therefore i can produce all sorts of chemicals by this woderful method!

Darkflame, it should work, and does for most people. But the last time I tried to get CuSO4 like that, it didnt work. I dont know why but I just got a crapload of light blue copper hydroxide precipitate Maybe you'll have some luck or maybe I just messed up Tell me how it goes if you try it

Esplosivo, next time I get such a contamination, I'll be sure to:
1) not chuck the solution after the test
2) take a picture after the test
3) boil the solution
4) ask for more tests

If only I had NaOH

Oh well, Im setting up the second run now. Hopefully, we wont need to resort to the above 4 resolutions

Edit: Here's my new pvc protected electrodes. They're gonna be used for the HCl/NaOH cell Im planning on making this summer too



[Edited on 28-3-2004 by Saerynide]

[Edited on 28-3-2004 by Saerynide]

Dont judge a copper salt by its color.....

I just added hot concentrated NaOH solution to a concentrated CuSO4 solution and got some dark-green precipitate which dissolved under the addition of more water to give a almost black solution.

Then I added some CuSO4 to an cold NaOH solution and got a deep-blue precipitate.

Temperature and concentration matters

[Edited on 28-3-2004 by Organikum]

And after my quick and dirty experiments the hard truth from the MERCK-index:

- copper sulfate dibasic: Cu3H4O8S, blue-green, rhombic, bipyramidal crystals. Practically insoluble in water.

- copper sulfate tribasic: Cu4H6O10S, very finely divided, light-blue, gelatinous particles. Practically insoluble in water.

- Copper hydrate: Cu(OH)2, blue to blue-green gel or light blue crystalline powder. Stability is dependent on the method of preparation, may decompose to black CuO on standing a few days or upon heating. Practically insoluble in water. Sol. in concentrated alkali when freshly precipitated.



So I got CuO mostly in my first experiment and a mixture of everything in my second experiment I guess (no CuO up to now though)

Quote:

Originally posted by Saerynide Here's my new pvc protected electrodes. They're gonna be used for the HCl/NaOH cell Im planning on making this summer too

Yeah I know. Im making bubblers for the Cl2

I wouldnt dare mix H2 with Cl2. It becomes explosive

Also, the HClO formed would break down into HCl and O2. Ive tried shaking Cl2 into water before, and it does yeild HCl. I saw the O2 bubbles coming out of the water

There was some thread awhile ago saying that NO3- can be reduced at the cathode. Which makes making HNO3 this way would be very hard and tedious, but if there's a will, theres a way I forgot which thread it was though...

Im gonna put the HCl/NaOH maker outside anyways, so there'll be lotsa light for it. Im so not getting Cl2 poisoning again, so it wont be anywhere near indoors

Mg(OH)2 is insoluble and it precipitates out of the solution You get a slightly milky solution if its dilute, but you get a layer of white amorphous stuff if its concentrated.

Edit: Nooooooo!!!! Contamination again!!!!

How far do you hafta go to have no fscking contamination?!?! I already washed ALL the equipment with dH2O TWICE already Maybe the silicone doesnt make as much of a water proof seal as I hoped




The contamination's not as bad this time though. I tested the pH of the two solutions. It was 3 and 11 only

[Edited on 29-3-2004 by Saerynide]

Come on Saerynide. Look at it on the good side, now you can carry out an analysis on the stuff . Its fascinating though. I cannot immagine the source of impurity. What water did you use? What was the source of the chemicals electrolyesed?

Lol, I guess I could have some fun with it now But no H2SO4 for making sugar turn to carbon or making oil of wintergreen

I used bottled distilled water from the supermarket and MgSO4.7H2O from the drug store, so it *should* be pretty pure. I also covered the cell with Glad wrap to keep dust from getting in.

I just thought of something. There would be an equilibrium in the cell because the electrodes can only draw so many anions and cations to them at any moment, so some ions would be crossing the salt bridge and reacting back with the acid and base to make the salt again, right? That would mean, the pH can only go so low, and would level off. So, if after each run, I filter the catholyte out to remove the Mg(OH)2, then run it again, and keep repeating this, I would eventually remove all the Mg2+ from the cell? That would leave me with a salt free acid?

Considering the fact that I am extremely tired/sleepy right now, it might be all gibberish

Ohh!!!! The time when I tried to make CuSO4 using a paper towel salt bridge, MgSO4 electrolyte ,and a copper penny anode, I *did* get CuSO4 but I thought I got Cu(OH)2. So that light blue precipitate was the tribasic stuff??

Btw, I looked up the definition of di/tribasic, and I dont understand how CuSO4 could fit the definition. Also, I dont understand why there are all those extra O's, H's and Cu's

What should I try tomorrow? I could 1) filter out Mg(OH)2 and electrolyze again or 2) Try to plate out the metal ion contaminant.

Id like to try plating out the metal, because it will either remove the contaminant (best case scenario), or end up concentrating the acid to the point that the bit of metal is irrelevant (still good)

But, how am I gonna keep the freshly made metal from reacting with the H2SO4? More over, what if the H2SO4 reacts with my cathode??

Analysis would have to wait til Friday. Ive got a ton of tests to study for

Btw, how do you guys fill your salt bridges? I had to shove a smaller tube into my bridge, dunk that under the solution, and use a syringe to suck up the liquid. This way is *very* painstaking cause I have to do it many times. Bubbles always get in and liquid goes into the syringe! I was so desperate once I even tried syphoning up the solution. That left me choking on a mouthful of nasty MgSO4

Does anyone pity poor me?? *sniffle*

got somthing to help in the quest for purer sulphuric acid

See attachment:

Dont run on batteries. It'll cost you a fortune If you have an old computer that you're not using, take out its power supply, short the green to a black on the mobo connector and voila! Instant electrolysis powersupply To run a cell, hook up a yellow or red for the positive and a black for the negative. Check the key stuck on the power supply to see the voltages and amperages of each lead.

Nice idea for the acid filter But can we get activated charcoal here in drug stores? Also, were could we buy fiberglass cloth

I dunno, but i will check up real soon in the stores. As for your old computer idea, its good but will it damage the computer permenently?

Well, I heard that power supplys can get killed from overloading and stuff, but mine has been abused for a long time and its still alive

Just take the power supply OUT of the computer to keep your hardware safe.

Ask axehandle, hes good with this stuff

Sweet I must check my local aquarium shop

Btw, how does it "absorb" ions? Does it react with the ions?

Edit: About how many times can the carbon be reused?

[Edited on 31-3-2004 by Saerynide]

My god, thats like burning it. I might as well buy some new stuff cause it'll probably cost less than the gas needed to heat it

Progress!

I electrolyzed the contaminated H2SO4 for a few hours. The stainless steel knife was coated in a tan coloured stuff that looked like MgO which could be easily scraped off the knife. Then I filtered the solution 4 times, using more and more filters each time. The acid is now almost clear, and the pH has decreased slightly, from 4 to 3.5ish, judging from the indicator strip.

Tomorow, I will electrolyze it some more, then try to concentrate it to about half its volume

I just had to give this a shot

I got a flower pot with the hole plugged and a plastic box where I placed 5000ml of cold tap water in the box and 1500ml in the pot. I took a sheet of pglass and drilled a hole in the middle to support the electrode. About 330g of MgSO₄ was disolved into the water in the box and 100g in the pot. both electrodes were made of lead from fishing weights.

I am running this at 5v/20amps. At first nothing seemed to happen but after a while small bubbles streamed off so the current densitry is low but this seems to be ok. The pH of the outer solution is red at about 4 using my paper. The solution is beautifly clear no hint of contamination from the electrodes. In the inner pot solution the pH is green at about 9 due to the pressance of Mg(OH)₂. I don't see a persipitate of Mg(OH)₂ yet but I have only run the cell for a few hours so it may be yet to come.

My cell is huge; 6500ml total! If I can get good cheap clear H₂SO₄ from it then I may never buy the stuff again! A good cheap source of Mg(OH)₂ will be handy as well. If this trial run is good then the "S Cell" may be a permanent addition to the garage/lab area. I could just push it into the corner.

The salt bridge Saerynide is using seems dubious to me. Filling it would be hard and it may contaminate the 2 solutions resulting in the formation of more MgSO₄!

Next day I will pipit off some liquid and do my "Acid Test"(pun intended) by heating my 200w soldering iron up and sticking the tip in the liquid. If all goes well I will see SO₂ fumes(hopefully not so much as to injure me <b>again</b>!

Wait till the 'morro for the latest results!

The only I reason Im using this salt bridge is because I cant find an unglazed flower pot

Living in Singapore can't be so good for free market capitalism; its the size of one of our states! It seems to me that rockwool inside pvc tube would be a better bridge and that a wooden bowl could act as a better bridge but not for strong acids/bases! It might contaminate the solutions even then. You might want to try a 'glazed' pot even then. I got one I thought was glazed(it felt smooth) but it works. Now if its shiny and a difrent color then its a safe bet it realy is glazed

I'll give one of those orchid farms or those warehouse-sized flower shops a try. Probably wont have time to get one til around May cause of all the exams coming up

I heard that 30% salt (by wieght, I would assume) was best for electrolysis. I have no idea why though, maybe it has something to do with diffusion and equilibrium? Maybe someone here can explain it to me or correct me

Results!

I ran the cell over night and the pH is 10 for the Mg(OH)₂ and 2 for the H₂SO₄! The pot has lots of milky white Mg(OH)₂ coating the inside of it and on the bottom. After doing the Acid Test by sticking a hot soldering iron in it and looking for SO₂ I saw some! Now I am going to boil the 5000ml down outside!

Nearly free Sulfuric Acid at last!

woooohoooo

Quote:

Originally posted by Quantum I ran the cell over night and the pH is 10 for the Mg(OH)<sub>2</sub> and 2 for the H<sub>2</sub>SO<sub>4</sub>! The pot has lots of milky white Mg(OH)<sub>2</sub> coating the inside of it and on the bottom. After doing the Acid Test by sticking a hot soldering iron in it and looking for SO<sub>2</sub> I saw some! Now I am going to boil the 5000ml down outside! Nearly free Sulfuric Acid at last!

Damn!

I have not yet been able to boil it down but somehow I don't think my yeilds will be very good I may be better off with buying it but I called the only hydroponics store nearby and they don't know whats in the acid solutions! They do however have 35%H₂O₂!

Do you guys think its worth buying some "pH Down" and then testing it by heating a drop till I hopefully see SO₂ fumes is a fairly safe bet? Im willing to try most anything.

Great Progress!

Tried this crude version over the sunday. I set up 2 bowls with MgSO4 dissolved in them.The anode side ihas slightly more solution than the cathode side. For the salt bridge, i used a paper towel. Then i connected the whole thing to a 9V battery. I used copper electrodes as i do not have any carbon electrodes yet. Over 1 night, the anolyte turned blue and at the cathode side, there is a white coating of Mg(OH)2. Additionally, there are pieces of copper in the anolyte as the copper electrode corroded away.

The cell is still running now, and i am so excited!! There are pictures attached:

And another one:

And another one:

Good work. Seems to be working pretty fine. After you've changed the electrodes to carbon rods just post a picture (1 not 3 ) of the apparatus after a run. This is just to check for any brownish coloured solution, which might have been 'masked' by the copper (II) sulphate formed in your case. Thanks.

God dammit. I ran the cell again, and this time there was contamination AGAIN. Same tan/brown shit. I swear, the MgSO4 must be contaminated.... Shit like this doesnt hapen 3 times in a row

Im getting myself a NEW box of MgSO4 tomorrow

Ok, liked to add this pH test for my catholyte is 10. And also i can have a nice blue colour for anolyte, with some pieces of copper inside.

I don't have any carbon rods at the moment, i tried to pry the metal cap off the battery but i can't!!!

You guys wont believe what happened last night. I had my cell running on my desk, and my cat was kinda frisky for some reason. He trampled all over my desk like he usually does, but he usually stays away from where I run my cell. Well last night, he wandered over there to take a look, and as he turned around to leave, he swipes the anolyte RIGHT OFF the desk before my very eyes I caught the container as it fell, so thankfully i didnt get a mess of broken glass. But I did get a huge splash (complete with long trickle marks) on the wall and a huge splash + puddle on the floor. I had to clean the whole mess before mom came up stairs and was rushing like freak to soak up the mess. Paper towels dont absorb salty + acid water very well

Gaaargggghhhh!When i tried to prise off the metal cap of the battery today, some black stuff presumbaly carbon, spurted out of the can!!!It reached 1.5 metres from the table and hit the ceiling. Everything within 1 m radius was affected. I had to clean up!! Worse still, i was hit by it in the right eye!!!!


I will never ever try to get carbon rods from batteries.


Regarding the porous pot for use as diaphrahm in electrolysis, can i use multiple filter papers as a diaphramn?? Other than using ceramic pots.

After running the cell for so long I have also got the same brownish tinge at the anolyte. Analysis ahead.

Thanks for the info. hodges. Will reduce the voltage next time, probably using some small resistors in parallel to the electrolysis set-up.

Could copper sulphate be used instead of magnesium sulphate. Copper sulphate is much more available and much more cheap (in my case at least). It contains only some impurities such as sodium sulphate and chloride in small quantities.

darkflame89, the black substance in the can is mostly MnO2. It is very difficult to clean. Next time try pulling the carbon rod out slowly, rotating the rod slowly as you pull it out. It only requires some patience As half the rod is out, the rest of the rod can be easily pulled out. The metal cap can be filed out.




[Edited on 9-4-2004 by Esplosivo]

OMFG... Im so sorry that you got sprayed right in the eye! Are you ok?? I feel so bad cause I suggested you to get them from batteries

Pressure mustve built up in that battery, like how faulty batteries explode for no reason.

Wow, youve gotten the brown tinge too? So Im not alone... I thought MgSO4 just didnt like me.

Btw, Organikum, what do you mean by H2SO4 in the cathode side?? Isnt it on the anode?

Edit: Someone said something about how sulfates can be oxidized by electrolysis. Maybe electrolysing it for so long changes it, so its not contamination??

[Edited on 9-4-2004 by Saerynide]

Yah, learning that fire is dangerous by burning the hand is a hard way to learn. I going to have glasses on next time anyway. There must have been a pressure built up. But it is a new battery!!! Its a Energizer battery, the battery cap is not directly connected to the carbon rods. Therefore I still don't have the rods.

So now i have got to wait until after the mid year exams to buy some graphite drawing pencil and somehow get the leads(I have no idea how )

About the brown coloration, maybe it is because you all left it out for too long?

Dont use energizer! Those are alkaline. Get those el cheapo ones like Eveready (S$ 2.50 for 2 - the ones in my guide pics) or the S$1.20 for 2 ones (the red ones with silver rings/stripes).

Edit: I also need to learn to use eye protection. I once had a container of acetone I was distilling shatter and splash me right in the face

[Edited on 10-4-2004 by Saerynide]

Look at this:

http://www.bartleby.com/61/56/S0875600.html

http://www.chemicalland21.com/arokorhi/industrialchem/inorga...

http://tis.eh.doe.gov/web/chem_safety/Docs/h2so4.pdf

http://www.twistedinternet.com/library-files/Drugs%20n%20Stu...

All four sources say that H2SO4 can be brown, but depending on its purity. However, not a single source (Ive searched for a LONG time) *defines* "depending on purity". So, do they mean concentration?? Contaminants?? And if so, what *kind*??

So, maybe we do have H2SO4, but just the brown kind

Btw Esplosivo, since youre the analysis expert, tell me how the analysis goes. Im very eager to know your results

This dark brown colouration of sulphuric acid is new to me. I have 98.9% GPR sulphuric acid at home and it is a colourless viscous liquid. Could any one provide more information about what this colouration of sulphuric acid is due to please.

Analysis is going to be carried, but not soon, since I'm am quite busy lately Currently I am also running the same set-up but using copper (II) sulphate. After 24 hrs the cathode was completely plated by copper and the anolyte gained a sort of greenish blue colour. I will let it run for an other couple of hours, then we'll see.

YESSSSS!!!!!! That means we've had H2SO4 all this time!!!!

Why didnt you tell us this earlier?? All this time Ive been trashing it thinking it was crap

All the money I wasted on MgSO4 just I was kept on starting over!!

Edit: Ooooooohhh!!! Maybe the organic crap is from the paper towel salt bridge!! I do realise half of my salt bridge goes brownish while the oher half stays white

[Edited on 10-4-2004 by Saerynide]

So the brown coloration is nothing??!!yay!!

OK, got a new idea here, using the same setup, but instead of carbon electrodes ,we could use aluminium ones!!
Thats because, aluminium sulphate will be formed in the anolyte. And this hydrolyses in water to give you insoluble gelatinous white solid as Al(OH)3 and SULPHURIC ACID!!! The products are still the same at the cathode side.

This means as long as i can get rid of the aluminium hydroxide, i can get sulphuric acid!!!

And, that means i don't really need to use carbon electrodes!! And no, spraying of MnO2 paste into my eye!!

In fact, FeCl3, hydrolyses too to HCl and Fe(OH)3.

I got this from a book called Chemistry potpourri. Singapore hardly sells books like this. I got from Science Centre here.

The process is taking too long to produce a small quantity of acid. The carbon electrodes, which are correded at high voltages must be replaced, but with what?! If the carbon rods could be replaced by some other inert material (which is not gold and neither platinum ) the process could be scaled up by increasing the voltage right? Does anyone have any suggestions.