highpower48
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Dark Sulfuric Acid
Last summer I bought a couple 850ml 98% sulfuric acid that came plastic bottles. I haven't needed them till now and noticed when I removed them from
the plastic bag and light free box that they have turned very dark, close to black. Guess my question is: Is there any issue with this acid? Pretty
sure the plastic bottles are the cause. But can i use the acid as normal 98% sulphric acid?
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highpower48
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By the way the acid came from Duda Diesel
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byko3y
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Sulfuric acid might have reacted with something. Your actions depend on purpose of the acid, it's either redistillation, destruction of organic matter
by peroxide, or just use the acid as is.
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AvBaeyer
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I have purchased sulfuric acid from Duda in the past. It arrived nearly colorless in plastic bottles but started to darken after a short time. I
transferred the acid to glass bottles and it has stayed nearly clear for almost 2 years. My advice is to get strong acids into appropriate glass
bottles as soon as you can.
AvB
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greenlight
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I have a large HDPE container with sulfuric acid that I pour smaller amounts into a 1 litre Duran bottle. The HDPE container is a couple of years
old.
I have attached a picture of the acid after it has been poured into the 1 litre storage bottle for the fridge.
Also attached, is a picture of the old stuff next to new acid from a smaller bottle brought 4 months ago.
The darkness seems to have no negative effect on the acid and the darker coloured acid works just as good as the new stuff. Just make sure it is
tightly sealed in its container.
[Edited on 25-3-2017 by greenlight]
 
[Edited on 25-3-2017 by greenlight]
Be good, otherwise be good at it 
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LD5050
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Should H2SO4 be kept in a light proof container? Does it matter? I keep mine in a clear glass jug. I distill it from drain cleaner. It comes pink but
after heat is added it becomes clear even before it condenses in receiving flask.
Maybe just try heating it and I bet it will become clear...
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greenlight
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I don't think it needs to be in a light proof (amber glass) container.
I keep mine in flass bottle in fridge so there is no light anyway in there.
I used to boil down 50% sulfuric acid to obtain a higher concentration and it was clear to start and always ended up darker coloured when finished...
I think my cause is just these HDPE containers darkening it after long expsoure
Be good, otherwise be good at it
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XeonTheMGPony
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H2SO4 is inert to normal light, I store my distilled in a 1L reagent bottle with a glass plug and some teflon to seal and it sits on my counter top.
http://www.alchemylabsupply.com/Narrow-Mouth-Reagent-Bottles...
As said simply ensure a good seal.
Nitric is Photo sensitive it must be stored in amber, HCl in water can be stored in clear
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Texium
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Read the title of this thread at first as "Dank Sulfuric Acid"
I have a large jug of 91% sulfuric acid in an HDPE container and it's a light brown color, but works fine in reactions where that concentration of
acid is sufficient, and I try to use that for whatever I can. Where that won't work, or I don't want to risk impurities, I also have some good, clean
96% acid in a glass bottle that came from VWR. I haven't purchased sulfuric acid from Duda before, but that always seems to be the case with their
stuff. It seems like they package it immediately before they send it, so if you're ready with a glass bottle when it arrives you should be able to
transfer it before it pulls anything out of the plastic.
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Jstuyfzand
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Wrong part of the internet! 
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Melgar
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The dark color is usually from the lining underneath the cap. It's often made from plastic-coated paper, but moving the bottles around inevitably
gets acid in the crack between the cap and the bottle and it seeps into the edge of that paper disk, turning it to carbon particles. The acid then
drips down the inside of the container back into the rest of the acid, darkening it.
Adding a few mL per liter of peroxide to the acid and then heating it to peroxide's decomposition temperature will virtually always remove the color.
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Herr Haber
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Quote: Originally posted by highpower48  | | Last summer I bought a couple 850ml 98% sulfuric acid that came plastic bottles. I haven't needed them till now and noticed when I removed them from
the plastic bag and light free box that they have turned very dark, close to black. Guess my question is: Is there any issue with this acid? Pretty
sure the plastic bottles are the cause. But can i use the acid as normal 98% sulphric acid? |
Storing acid next to high powered speakers do that.
(if you play heavy metal for too long: same thing with kids)
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Eyeborg
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Melgar is probably right that the sulfuric acid was reacting with something in the cap. For some applications, dirty sulfuric acid is fine, but if you
want to purify it, you can distill it.
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