DCHAS-L Discussion List Archive

At 2:00 PM -0700 3/29/07, Larry D. McLouth wrote:
>What is your practice for storing  nitric and hydrochloric acids? 
>Do you keep them separated to prevent mixing?
>
>I realize they are intentionally mixed to make aqua regia, (under 
>controlled conditions using a fume hood).  But this evolves chlorine 
>and nitrosyl chloride gases...so there is a concern about storing 
>these two acids together.
>
>I plan to tell our users that it's okay to keep these two acids in 
>the same storage cabinet but that they should be kept on the same 
>shelf and in individual photo trays to prevent accidental mixing in 
>the event of a spill, leak etc.

Hydrochloric and nitric acids are incompatible and should NOT be 
stored together.  It says so on the MSDS for either.  Just because 
"everyone does it" without major problems doesn't mean that the 
practice is recommended safe, and suggesting otherwise could set one 
up for some serious liability, no doubt.

I actually see the gas phase reaction of the two being more likely 
than a double spill in the same cabinet.  For example, many folks 
store their acids and "ammonium hydroxide" (concentrated aqueous 
ammonia) bottles in the same cabinet....and wonder why they are 
always coated with a white substance (ammonium hydroxide).   Bases 
should always be stored away from acids, of course.

 From a practical sense, I know from my lab experience that many 
(most?) chemists store their hydrochloric and nitric acids in the 
same cabinet, if only because they can't dedicate a separate space. 
While trays are a good idea, a subdividing the cabinet so the two 
halves can't exchange air or liquid - or perhaps a sealed 
overcontainer within the cabinet, are probably better ideas.

At the risk of self-promotion, Eagle Manufacturing and other 
companies make polyethylene acid storage cabinets that make the 
segregation of nitric and hydrochloric easier.  Some of these have 
internal dividers/compartments.  Alternatively, one can buy a small 
cabinet (4 gallon) for the nitric acid as hydrochloric and many other 
acids can be stored together.  See here: 
http://www.safetyemporium.com/ILPI_Site/WebPagesUS/safety/cabinets.htm 
and click on any of the items for more detail and bigger pictures.

Rob Toreki
-- 
   =====================================================
Safety Emporium - Lab & Safety Supplies featuring brand names
you know and trust.  Visit us at http://www.SafetyEmporium.com
esales**At_Symbol_Here**safetyemporium.com  or toll-free: (866) 326-5412
Fax: (859) 523-0606, 4905 Waynes Blvd, Lexington, KY 40513-1469