Date: Tue, 17 May 2011 19:24:13 -0400
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: "Bell,Martin" <mwb32**At_Symbol_Here**DREXEL.EDU>
Subject: Re: Piranha solution
In-Reply-To: <5B0B5ACDD36F9340940DAC5575821D870112D364**At_Symbol_Here**>

This is what I know about piranha solution:

- add the hydrogen peroxide to the sulfuric acid.
- use Pyrex in the hood. 
- keep container open until cool due to strong exothermic reaction.
- do not store the mixture due to pressurization and explosion. If storage necessary use one way vented cap. 
- do not add water to mixture.
- search glove selection charts for the material or each chemical. 

Martin Bell, CSP CHMM
Environmental Health and Safety Manager
Drexel University

On May 17, 2011, at 7:02 PM, "Johnson, Amy Carr" <amy_johnson**At_Symbol_Here**HARVARD.EDU> wrote:

I have been reading about how to make Piranha solution and I keep coming across this statement,  "Add the acid to the peroxide, although some authorities disagree"   Why would authorities not agree that adding acid to water instead of water to acid is best?

I have seen some say add acid to peroxide for initial solution, but when refreshing, add aliquots of hydrogen peroxide to Piranha mixture.  Is that ok?

We recently had an incident when Piranha came in contact with ferric chloride and instantly reacted

violently Was this due to the metal, the fact that both are oxidizers, both, or something else?

I have read that neoprene gloves should always be worn.  True?

What type of glass is appropriate for containment?

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