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aga
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Sulphuric acid
Forgive me if this has been endlessly discussed elsewhere - i did search this forum and the web (in that order) for guidance, but found literally
nothing.
I've recovered and filtered about 5l of car battery acid, hoping to boil it down to get concentrated H2SO4
The first 600ml i have boiled down to 120ml of what appears to be useless garbage.
It has a very low pH, going red with methyl orange.
Dissolves kitchen towel rather quickly, but without blackening it, and refuses to react with NaCl.
It stubbornly remains a brownish colour, and seems to crystallise almost to a solid mass when cooled to RT. Maybe it's a polymer in there - hard for a
noob to tell.
Is there a particular additive generally found in car battery acid, or have i discovered TotalNoobolitic-TetraDumbide Acid as a new compound ?
[Edited on 1-5-2014 by aga]
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blogfast25
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If it came from an old battery, G-d only knows what was in there. Contaminated rain water rather than weak sulphuric acid is certainly a possibility.
You should take a sample and carry out a simple titration. Or use one of these handy little hydrometer thingies to measure car battery acid strength
with.
W/o knowing what you started out with, there's no way of telling what you'll end up with...
The methyl orange test only tells you pH is less than 3.1, that's not very low. You should be getting less than 1 by now (assuming the starting liquid
was real, weak SA battery acid) but MO can't tell you that. Universal pH paper is needed at a minimum.
For reaction with NaCl you need > 95 %, I'm fairly sure...
[Edited on 1-5-2014 by blogfast25]
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Zephyr
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Really? You didn't find anything on the web to help you?
Here are some threads that discuss the purification of sulfuric acid.
http://www.sciencemadness.org/talk/viewthread.php?tid=3722
http://www.sciencemadness.org/talk/viewthread.php?tid=14570
http://www.sciencemadness.org/talk/viewthread.php?tid=14857
https://www.sciencemadness.org/whisper/viewthread.php?tid=19...
Good luck!
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aga
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Yep. All from old batteries.
Some were 'recycled' and i know they had some sort of additive put in them.
Sadly can't titrate at the mo as i am still in mourning at the loss of my burette.
Well, i could, but it seems so much better with a burette 
Bugger. I've started at the wrong end again.
Best label the bottle 'brown stuff from old car batteries' and hide it at the back of the shelf.
If only i had a Tricorder ...
Oh well, reverse electrolysis of copper sulphate then, and back to boiling.
Thanks for the reply.
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aga
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Woo ! There's Hope !
Cheers !
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Bert
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Did you use a functioning car battery AFTER FULLY RECHARGING IT?
Perhaps a review of Lead acid storage battery chemistry will explain this?
Why work so hard for electrolyte?
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aga
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DOH !
Nice bottle of lead sulphate aga.
Shame it's contaminated with all that other mess, including a small quantity of Sulphuric acid ...
Thanks for the pointer to my obvious mistake Bert.
I'm way back at the Beginning, so learning how to actually do the simplest things is still all new and fun !
[Edited on 2-5-2014 by aga]
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hissingnoise
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| Quote: | | Best label the bottle 'brown stuff from old car batteries' and hide it at the back of the shelf. |
Your acid apparently contained SiC as a fine suspension ─ it was used as additive to minimise crystal-growth between plates!
Concentrating the acid decomposes SiC and released carbon causes a brown colouration; further heating oxidises the carbon, CO2 bubbles off
and SiO2 precipitates!
The acid is now water-white @~98% . . .
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vmelkon
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Why don't you measure the density?
All you need is a graduated cylinder and a balance. If you don't have them, buy it off of ebay, which is what I did.
It comes in handy for the ethanol I produce, the car battery that I distillled, the chloroform that I produced and many other liquids.
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blogfast25
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Careful with lead, aga. Very poisonous.
Not really worth extracting the H2SO4 from it. 95 % H2SO4 is available as drain cleaner, at least here in Old Blighty.
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aga
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@hissingnoise : cheers for telling me what the brown stuff is !
However, as Bert's link to cell chemistry pointed out, the batteries were flat, and so getting acid from them in that state would be silly.
@vmelkon : yes, good idea. I didn't think of testing the density, as i got fixated on the brown stuff.
@blogfast25 : Yes, very careful with lead, acid, but strangely not beer, and never mix the beer with either (dilutes it).
In Spain i have not encountered OTC sulphuric acid yet, but then, i have not looked too hard.
I guess i could just stuff the mix of Lead sulphate, oxide, acid and silicon back in the battery and send it off for recycling.
If i were to dump the nasty mixture, what would you peeps suggest to 'neutralise' the lead and acid ?
Would sodium bicarbonate do anything to render the Lead less toxic ?
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blogfast25
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Quote: Originally posted by aga  |
If i were to dump the nasty mixture, what would you peeps suggest to 'neutralise' the lead and acid ?
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The best idea.
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annaandherdad
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If you can't find sulfuric acid on the forum, try spelling it "sulfuric" instead of "sulphuric". Also, google works better than the forum search
engine, include "sciencemadness" in your search.
It was a mistake to play with this stuff out of old batteries. Now you have an acidic mess of poisonous lead compounds. There is nothing you can do
to make the lead less poisonous, but with some effort you could precipitate it as a carbonate or other insoluble salt, which would be better than
something soluble. You'll have to get rid of it some place where they take lead. Maybe you could just pour the gunk back into old battery cases and
take them to a battery recycling center.
You can't concentrate sulfuric acid by boiling it, at least it's not practical at home. This has been covered on the forum elsewhere.
Any other SF Bay chemists?
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Manifest
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How can you not concentrate by boiling?
I have done it before with success.
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blogfast25
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| Quote: Originally posted by annaandherdad | | There is nothing you can do to make the lead less poisonous, but with some effort you could precipitate it as a carbonate or other insoluble salt,
which would be better than something soluble. |
Brilliant! Let's create loads of bubbles and froth by neutralising fairly concentrated sulphuric acid with sodium carbonate!
No. Just pour the mess back into the battery if possible and dispose of it as you should.
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unionised
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May I invite you all to consider briefly how a car battery works?
Given that the plates in a discharged battery are made of lead sulphate and sitting in a solution of sulphuric acid, how soluble do you think lead
sulphate is in those circumstances?
So "with some effort you could precipitate it as a carbonate or other insoluble salt"
Did anyone consider the sulphate as such a salt?
(Granted, the carbonate is about ten times less soluble).
Having said that, "Just pour the mess back into the battery if possible and dispose of it as you should. " is probably the best advice so far.
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HgDinis25
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Lead Sulfate isn't that giant scary beast that will poison you just by looking at it. It is fairly insoluble in water.
If you can't put everything back into the battery, I suggest you dilute your sulfuric acid and then add enough NaOH to neutralize it. Then add more
NaOH to neutralise any soluble Lead ions still present. This will make Lead Oxide, more or less harmless.
To any other solutions that may contain soluble Lead Ions, add NaOH too. Then, you can simply filter everything and discard your aquous phase. Then
put your insoluble Lead crap and stuff it into a ZIP bag, stuffed in another ZIP bag that has been stufed in yet another ZIP bag. Then garbage.
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unionised
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Do bear in mind that lead sulphate is reasonably soluble in sodium hydroxide solution.
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aga
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Concentrated Lead/Sulphuric mess all back in the battery, and goes for recycling tomorrow.
Another dead-end, but learning all the way.
The colours, and the changes thereof, are beautiful.
Same as my recent neodymium extraction : i now have beautiful pale violet iron III sulphate paste.
@Manifest : I was also surprised at the comment:-
"You can't concentrate sulfuric acid by boiling it, at least it's not practical at home"
@Annaandherdad : presumably you're saying to NOT do this in a home kitchen, with which i wholly agree.
Doing 250ml on a temperature controlled hotplate in a borosilicate vessel, in a fume hood, with a silicon sealed glass-trough base should be OK ?
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blogfast25
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Here's a decent 'how to?' on the subject. Jeffrey used to hang out here sometimes.
http://amazingrust.com/Experiments/how_to/Concentrating_H2SO...
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IrC
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Thank you for that link, never found this site before. He has a great page on making Bismuth crystals, a hobby of mine.
"Science is the belief in the ignorance of the experts" Richard Feynman
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S.C. Wack
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If you're producing fumes like that link does, you're not concentrating the acid...as I've said before the fumes seem to be the result of atmospheric
water, like the hot acid wants it so bad that it'll jump right out of the flask for it...
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hissingnoise
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| Quote: | | If you're producing fumes like that link does, you're not concentrating the acid... |
That fuming does actually lead to 98% H2SO4!
My first attempt filled the open shed I used with a choking vapour . . .
And I've used the procedure several times, since!
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blogfast25
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| Quote: Originally posted by S.C. Wack | | If you're producing fumes like that link does, you're not concentrating the acid...as I've said before the fumes seem to be the result of atmospheric
water, like the hot acid wants it so bad that it'll jump right out of the flask for it... |
How can he NOT be concentrating acid when the volume is decreasing and the BP of water is much lower than that of pure H2SO4?
Hot acid jumping out of the flask to grab water???? Explain?
@IrC: thanks. He has some interesting stuff.
[Edited on 5-5-2014 by blogfast25]
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Manifest
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Aga, you quoted wrong, I defended boiling acid to concentrate it.
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