When Pottasium Dichromate is mixed with Hydrogen Peroxide, Dichromate is reduced (as shown in answer key to test). However since H2O2 has a greater reduction potential than dichromate, should H2O2 undergo disproportionation rather than dichromate reducing.
Answers
Answer:
Explanation:
When hydrogen peroxide is added to a acidified solution of dichromate (or any other Cr (+VI) species) , a very complicated reaction occurs. The products depends on the pH and the concentration of Cr.
Cr2O72- + 2H+ + 4H2O2→2CrO(O2)2 + 5H2O
A deep blue violet coloured peroxo compound is formed. This decomposes rapidly in aq solution into Cr3+ and dioxygen.
In less acidic solutions of potassium dichromate an hydrogen peroxide give salts which are violet colored and diamagnetic. These are thought to contain [Cr(O2)OH-], but the structure is nt known as the compounds are explosive.
In alkaline solution with 30% hydrogen peroxide, a red-brown compound K2Cr3O8 is formed which is a tetraperoxo species [Cr(O2)4]- and contains Cr(+V).
In ammonia solution the dark red brown compound (NH3)3CrO4 is formed which contains Cr(+IV)