Iron(III) chloride "catalyzes" (not sure it is a true catalyst as the resulting mixture ends up red-orange rather than the original yellow-orange). the decomposition of hydrogen peroxide. I do a chemistry demo wherein I add 1.5 g of iron(III) chloride (dissolved in about 10 mL of water in a 20 mL vial) to 150 mL of 10% H2O2 (freshly diluted from the commercial 30% solution) in a 1-L Pyrex graduated cylinder. If the 30% H2O2 used was "fresh" (if not as "potent", use less than 100 mL of water and 50 mL of H2O2), the mixture turns black/brown and effervesces. As the exothermic reaction proceeds, it goes even faster, a column of foam rising to near the top of the cylinder before the reaction subsides. I can see where adding any solution containing >10% H2O2 to iron(III) chloride would result in an immediate, violent reaction. Regards, Larry Wilkinson Jim Tung
To Sent by: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU DCHAS-L cc Discussion List Subject 05/18/11 09:41 AM Please respond to DCHAS-L Discussion List Might the violent reaction between the solution and the ferric chloride be the result of forming Fenton's reagent? http://en.wikipedia.org/wiki/Fenton's_reagent On Tue, May 17, 2011 at 1:20 PM, Johnson, Amy Carr wrote: I have been reading about how to make Piranha solution and I keep coming across this statement,Ê "Add the acid to the peroxide, although some authorities disagree"ÊÊ 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.Ê 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.Ê True? What type of glass is appropriate for containment?
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