I will shortly be using $90~\%$ or higher concentration nitric acid in a home environment for the purpose of decapping ICs. I understand the corrosive dangers of nitric acid, and most of the important dangers of its reactivity (e.g. exothermic with water, don't make nitrobenzene, explosive nitrations are bad) and will be performing the decapping in a well-ventilated clean area. I'll also be wearing the best thick acid-resistant gloves I could find, since it seems nothing is really rated for RFNA handling.

My primary concern is handling a spillage. I know a common disposal technique for liquid waste is to feed the $\ce{HNO3}$ very slowly into water to dilute it, then add a base such as sodium bicarbonate to level out the pH, using an indicator mixture to monitor it. However, that's not so easy if the spillage is a few splashes on the workbench — I need a reasonably safe way of wiping it up and disposing of it. Someone told me that acetone wipes are an option for cleanup, but they couldn't remember where they'd read it, so I'm wary of accepting that advice without having it verified.

So, what're my options? How can I clean up a splash of RFNA off a work surface without doing myself (or the environment) any real harm?


1 Answer 1


Of course, you’ll want to prevent a spillage as well as possible (making sure the bottle doesn’t fall over etc.) but sometimes you just run into bad luck. Let’s hope that your work bench is at least capable of withstanding the acid for a minute or two — if you have a tiled working surface that would be preferred since they will almost certainly withstand.

If the spill is small — a few drops or so — I would take care of it by quickly adding large amounts of water (more than ten times the volume of spilt acid). I would suggest a wash bottle or something similar. Once you have added water to dilute the acid, you can wipe it up with standard kitchen wipes.

Yes, people are always told to slowly add acid to water and not the other way around. However, if it’s only a small amount of acid and using a large amount of water (and if the acid is not sulfuric acid) you can ‘get away’ with doing it the wrong way; the water will absorb the heat quicker than it can boil.

In case you spilt larger amounts, I would also prepare some baking soda to have around. Carefully (really carefully: it will bubble vigorously) sprinkle some of the baking soda onto the spill until the gas evolution is markedly reduced. Then continue as above, i.e. add water and wipe up with kitchen wipes. This intermediate baking soda step would mainly be to reduce the acid concentration by evolving $\ce{CO2}$ — it would be an overkill to use it on small spills, too.

Have all the required material ready, before you unscrew the cap of the acid bottle.

Finally, I would not use acetone wipes. Acetone can react with nitric acid in may unpredictable ways that you really don’t want to run into. Use water and simple, dry kitchen wipes.

By the way: Having eye protection (safety goggles) is greatly recommended.

  • 2
    $\begingroup$ Thanks for the answer. My primary work surface will be glass (I'm using an old chopping board) on concrete, outdoors but sheltered from weather -- I don't fancy explaining chemical burns on the kitchen worktop to my landlord. Eye protection is a great shout; I would've remembered it at the time but I didn't explicitly think about it until you mentioned it. I have a few pairs of old airsoft goggles that should do the trick. Water and bicarb seems like the safest and easiest option for cleanup, so I'll make sure to have those around in abundance. $\endgroup$
    – Polynomial
    Nov 12, 2016 at 12:16
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    $\begingroup$ Storage: Also note that fuming acid does just that it fumes. So storage inside is a bit tricky. A real chem lab would have a vented cabinet. $\endgroup$
    – MaxW
    Nov 12, 2016 at 12:41
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    $\begingroup$ Personal Safety - Eye protection is not just recommended, it is mandatory. You'll also need leather shoes that are full covered, and an apron or lab coat (full sleeves / long pants). Some sort of rubber gloves. If you spill the acid on yourself then you'll need a method to wash yourself off. (make do emergency shower...). You need to strip with no clothes over the head. So you may need bandage scissors to cut off clothes. You should also have some method to wash your eyes (some sort of eye wash). $\endgroup$
    – MaxW
    Nov 12, 2016 at 12:43
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    $\begingroup$ We don't talk enough about safety on this site. A lot becomes second nature after a few years in the lab, but it is always a good idea to review the safety plan for all steps that you would do in an experiment. The best thing is also to plan for minor problems and not to turn small mistakes into major STUPIDS. // Long sleeves, long pants, and non-absorbing shoes are to protect your skin. After six months of use all my lab coats had small holes here and there. Better to sacrifice the lab coat than my hide. $\endgroup$
    – MaxW
    Nov 12, 2016 at 18:38
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    $\begingroup$ Since we're talking safety - you should also make sure whoever else lives with you knows what you are working with, and if they hear horrible screams coming from the shed what they should do about it. $\endgroup$
    – Grant
    Nov 13, 2016 at 1:08

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