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darkflame89
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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:
Ignis ubique latet, naturam amplectitur omnem.
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darkflame89
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And another one:
Ignis ubique latet, naturam amplectitur omnem.
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darkflame89
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And another one:
Ignis ubique latet, naturam amplectitur omnem.
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Esplosivo
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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.
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Saerynide
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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
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darkflame89
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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!!!
Ignis ubique latet, naturam amplectitur omnem.
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Saerynide
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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
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Esplosivo
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I have set up and run the electrolysis for approximately 13 hrs right now. At the anode the pH is already acidic and there is no sign of
contamination. There is also a white precipitate of magnesium hydroxide at the cathode. The only problem is that the carbon electrodes I've used
are disintegrating into small black particles. The carbon electrodes are from battries. Does anyone have a suggestion to prevent this?! These
particles can be easily filtered off though. If I will have the time I will carry out a titration and a simple analysis after another 12hrs.
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Quantum
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Like I said before I have already run my cell and it works fine but sadly its realy not good for making sulfuric unless you can get 10s of liters of
the very dilute acid.
Now I have 5 liters sitting around along with some Mg(OH)<sub>2</sub>
I am going to pick up some battery acid soon along with a cheap hotplate.
What if, what is isn\'t true?
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hodges
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| Quote: | Originally posted by Esplosivo
The only problem is that the carbon electrodes I've used are disintegrating into small black particles. The carbon electrodes are from battries.
Does anyone have a suggestion to prevent this?! |
Keep the temperature of the solution down and keep the voltage down. You might try putting a lamp of the same voltage as your power supply in series
with your circuit to drop some of the voltage. You really only need a few volts across the electrodes; a higher voltage speeds up the proocess but
produces fast erosion of the carbon rods and may also result in production of other products (such as reducing the sulfate ion to sulfite or even
sulfide).
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Organikum
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I guess the main problem which arises here whilst electrolysing MgSO4 is connected to the ph.
A ph of 10 in the anode chamber just doesnt sound favoirable to me.
MgSO4 is just not very good for this, I would suggest to use FeSO4 so any available, which would for sure work much better and doesnt even require a
diaphragm.
If you want to stick with the MgSO4 I would suggest to change the liquid in the anode chamber often, removing the basic MgOH and refilling with
saturated MgSO4 solution. The cathode liquid should stay the same, H2SO4 in the cathode chamber favors the process.
god luck!
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darkflame89
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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.
Ignis ubique latet, naturam amplectitur omnem.
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Esplosivo
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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]
Theory guides, experiment decides.
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Saerynide
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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]
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Marvin
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darkflame89,
You learned the wrong lession. Wear eye protection when doing chemistry.
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darkflame89
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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?
Ignis ubique latet, naturam amplectitur omnem.
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Saerynide
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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]
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Saerynide
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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
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Esplosivo
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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.
Theory guides, experiment decides.
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Saerynide
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Finally! Something about the contaminants!
| Quote: |
Clear, colourless, odourless, dense, oily liquid when pure; yellow to dark
brown when impure.
Sulfuric acid is sold or used commercially in different concentrations,
including technical (78 to 93%) and other grades (96, 98-99, and 100%).
Impurities include metals such as iron, copper, zinc, arsenic, lead,
mercury and selenium, sulfurous acid (as SO2), nitrates and
chlorides.(6,14) |
From http://www.uwm.edu/Dept/EHSRM/EHS/SARA/MSDS/sulfuricacid2001...
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Organikum
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The brown color comes from oxidized organic matter - simply burned stuff. It is not related to concentration but to purity - high purity H2SO4 is
clear. But I know of no use of H2SO4 (except for analytical purposes) where the decolorization matters in any way. Industrial/technical grade H2SO4 is
utmost always brownish to almost black, I guess this depends mostly on the containers in which it was transported.
Battery acid is even more contaminated also it looks clear - on concentrating this stuff I alsways had a yellow precipitate which had to be filtered
out and the concentrated H2SO4 had a yellow tint whci I disliked. (looked like piss).
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Saerynide
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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]
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darkflame89
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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.
Ignis ubique latet, naturam amplectitur omnem.
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Organikum
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You wont get happy with Al electrodes, at least not in the H2SO4 compartment.
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Esplosivo
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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.
Theory guides, experiment decides.
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