SnailsAttack
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Irritation hazard of oxalic acid powder
If you've worked with acids you've almost certainly noticed the burning sensation from inhaling fumes or aerosols. I've found that the unique
properties of oxalic acid make it an especially potent irritant, documented in this short post.
Oxalic acid is by far the strongest acid that can be isolated as a dry solid. The crystals are brittle and easily crushed to a fine powder, and even
minute quantities of aerosol are highly irritating to the respiratory tract.
In my experience, manipulating even a few grams of the powder in an enclosed space requires the use of an aerosol respiratory mask (the COVID N95's
work fine) or fume hood. The aerosol does not significantly affect the eyes, but eyewear is still a good idea when working with the powder.
Simple actions like pouring or gently stirring the powder are enough to produce a noxious aerosol, which takes around 10-20 seconds to fully disperse.
I want to emphasize that spilling powdered oxalic acid poses a legitimate threat, likely comparable in effect to volatile acids such as glacial acetic
acid or concentrated hydrochloric acid.
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Alkoholvergiftung
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Thats why when i need an oxalic acid solution. I boil water and pure it over the oxalic acid. When you heat water and you put the oxalic acid powder
inside it you smell it sour imidataly. So do not boil an oxalic acid solution except you are outside or under a fumehood.
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bnull
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That crap is also volatile. I prepared a solution of oxalic acid in a test tube and gave it a few days to dissolve a small piece of metal. When I
checked the result, there was a fluffy white deposit at the mouth of the tube.
Keep all oxalic acid solutions in a capped flask, use stoppers in test tubes, avoid leaving them open to the atmosphere, especially in hot weather.
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Fery
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Oxalic acid is used to prevent clogging of blood samples taken from patients. The mechanism is by bounding free Calcium ions. Aside strongly acidic pH
the effect with Ca may also cause pain and damages of living cells. Cells cannot live without free Ca, it is important on membrane electric potential,
also second messenger transferring various signals from membrane receptors into effector organelles and also into cell nucleus.
Citric acid is used as anticlogging agent for blood samples too (binding Ca), heparin (different mechanism, blocking 1 step in protein cascade) and
various new anticoagulants.
When you eat Rhubarb it contains some amount of oxalic acid so there is a limit of that plant to eat. Excess of oxalic acid precipitates in kidneys in
a form of Ca oxalate and causes oxalate kidney stones (nephrolithiasis).
Small amount of oxalic acid in food does not cause any harm (strawberries).
bnull - oxalic acid also sublimes, it is used in treatment of varroa destructor infestation of honeybee colonies, beekeepers use
sublimators/vaporizers.
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violet sin
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Oxalic acid used as wood bleach.for taking dark stains out of fence and deck boards. As far as the strongest dry acid, idk about that. What about
sulfamic acid? Also available to the public in the form of tile haze remover/etchant. Nice chems to have around for home improvement projects. I've
not found either one to be particularly troublesome or irritating when using a few oz. Dare say I had far more trouble applying pool shock to my
pool, and even then it's only temporary irritation from inhalation/air-to-eye capture.
I'm in no way insinuating they are harmless. Though, I would point out all of those are used daily by the general public, generally safely too. It's
unfortunate you had a poor experience with oxalic acid; perhaps the form had a lot to do with your reaction. IIRC the wood bleach is crystalline
dihydrated version, little bigger than sugar crystals with very little powder for airborne spreading.
Good luck and safe handling
-VS
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SnailsAttack
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Quote: Originally posted by bnull  | | That crap is also volatile. I prepared a solution of oxalic acid in a test tube and gave it a few days to dissolve a small piece of metal. When I
checked the result, there was a fluffy white deposit at the mouth of the tube. |
Really, at room temperature?
I'll try to verify this by gravimetry.
First time I've heard of it,
but the internet says it has almost the same pKa as oxalic acid.
| Quote: Originally posted by violet sin | | I'm in no way insinuating they are harmless. Though, I would point out all of those are used daily by the general public, generally safely too. It's
unfortunate you had a poor experience with oxalic acid; perhaps the form had a lot to do with your reaction. |
I'm actually fine, haven't had a real accident with the oxalic acid powder. You'd have to screw up big time to maim yourself with
this stuff. Wish I could say the same about my liter jug of sulphuric acid drain cleaner, that thing puts the fear of god in me every time I have to
open the bottle.
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bnull
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| Quote: | | Really, at room temperature? |
Yes. It gets more noticeable as ambient temperature gets higher. It had been a rather hot week, about 27 to 32 °C.
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