Chemical Forums
Chemistry Forums for Students => High School Chemistry Forum => Topic started by: SinkingTako on October 19, 2013, 04:24:20 AM
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When Fe2+ is reacted with H2O2, in the presence of H+, the following reaction should take place:
2Fe2+ +H2O2 +2H+ :rarrow: 2Fe3+ +2H2O
However, in the lab, When H2O2 is added to the apple green solution of Fe2+ (without any acid), the solution turns orange, which is very very similar in colour to that of the Fe3+ solution. When acid is added, the solution changes colour back to the apple green.
Yet I think the green solution of H2O2, acid and Fe2+ formed is not simply Fe2+ again. When NaOH is added, a almost black ppt is formed, which is distinctly different from the brick-red ppt of Fe(OH)3, or dirty green ppt of Fe(OH)2. Also HCl (which is the acid I used) would definitely not been able to reduce Fe3+ to Fe 2+ again.
What can this black solid be, and what is the reaction of H2O2 and Fe2+?
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Fenton reaction
http://en.wikipedia.org/wiki/Fenton%27s_reagent