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Previous by Date: Subject: Re: [CSHEMA-L] University of Washington Hazardouse Waste Incident Date: Sat, 31 Mar 2007 06:43:36 -0400 Author: Ralph Stuart |
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I have to respectfully disagree with Jay's opinion below. Aqua regia is technically a 1:3 (or sometimes 1:4 depending on your source) ratio of HNO3:HCl. These solutions are unstable, and liberate NOx, NOCl, and chlorine gas. This makes the hazards of the mixed acids significantly greater than the sum of the individual hazards. The increased *hazard* of the mixed solution is undeniable. That said, the *risk* posed by the mixing of the acids is, of course, dependent on the quantities involved. 10 mL of each - low risk. 3 liters of each - run away! The *risk* assessment must also take into account the probability of the two containers being broken at the same time. Assuming these are stored in a cabinet without other incompatibles, then the chances of that are generally low. However, one can not discount the possibility of a pressure explosion of another bottle within that cabinet. For example, if someone accidentally introduced an organic into the nitric acid bottle, screwed the cap on, and put it away. Or if someone deliberately prepared an aqua regia solution and stored it in the acid cabinet: http://www2.umdnj.edu/eohssweb/aiha/accidents/explosion.htm#Two To summarize, the hazard is significant and the risk *can be* relatively low, but not infinitesimally so. Therefore, it is prudent to segregate the two acids. Rob At 9:23 PM -0400 3/30/07, Jay Young wrote: >To summarize, I see no significant hazard in the mixture of hydrochloric >and nitric acids which is greater than the hazards presented by the >individual unmixed, separate, acids. In my opinion, there is no good >reason to separate the two in storage. -- ===================================================== 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
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