Here is but a small extract from Atomistry.com on ZnO2 on a much larger discussion of Zinc peroxide based on extracts from the literature (link: http://zinc.atomistry.com/zinc_peroxide.html ), which the reader should note includes dated research:
"Thenard obtained an incompletely peroxidised oxide of zinc by (a) dissolving zinc hydroxide in hydrochloric acid containing hydrogen peroxide and
precipitating with an alkali hydroxide; (b) acting on gelatinous zinc hydroxide with hydrogen peroxide. "
Now, Zn(OH)2 + [2 HCl + 2 H2O2] is, in my opinion, not necessarily the same as ZnCl2 (aq) + H2O2. The reason is due to the unspecified concentration
of the HCl in question, for one, as for dilute HCl:
HCl (dilute) + H2O2 --> HOCl + H2O
This reaction is cited by Watt's as one of several preparations for Hypochlorous acid. To quote from "Watts' Dictionary of chemistry", page 16. "—6.
Addition of H2O2 Aq (containing 2.45 p.c. H2O2) to a large excess of Cl Aq produces HClOAq, according to Fairley (B. A. 1874, 57); if much H202 is
added, the HClO Aq is decomposed forming HCl Aq, H20, and evolving O." Link: http://books.google.com/books?pg=PA13&dq=Watt+preparatio...
But, with concentrate HCl, the interaction of HCl and Hypochlorous acid forms chlorine water:
HCl + HOCl = Cl2 + H2O (see http://books.google.com/books?id=zVIpX7rkk7oC&pg=PA15&am... )
In addition, with respect to the ZnCl2, if subject to concentration by evaporation, for example, the products could include say, ZnCl2.ZnO, but based
on recent work, more correctly, a tetrabasic zinc chloride, ZnCl2.4Zn(OH)2.H2O (see Wikipedia article on Zinc chloride hydroxide at http://en.wikipedia.org/wiki/Zinc_chloride_hydroxide_monohyd... ). My speculation is that perhaps the later compound, upon be reacted upon by the
H2O2 or HOCl, may be the source of the ZnO2.
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Here is another source, previously quoted in part below and also somewhat dated, available at http://tera-3.ul.cs.cmu.edu/NASD/4dcb85c3-9fee-4c83-9e6d-fe6... to quote:
"J. F. Eijkman boiled a soln. of zinc sulphate, which had been treated with enough aq. ammonia to dissolve the precipitate first formed, with30 per
cent, hydrogen peroxide. The pale-yellow granular precipitate is stable up to nearly 130°. It is soluble in aq. sodium hydroxide with the evolution
of oxygen; it explodes when heated to about 212°"
[Edited on 7-2-2014 by AJKOER] |