I combined and the solution went brown and slowly turned orange.with the evolution of a gas.. please write the equation between them.. very important and I need it for my science fair!
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3(H2O2 --> O2 + 2H+ + 2e-) ......................... oxidation
14H+ + Cr2O7^2- + 6e- --> 2Cr3+ + 7H2O.... reduction
-------------------- ------------------- -----------------
14H+ + 3H2O2 + Cr2O7^2- --> 3O2 + 2Cr3+ + 6H+ + 7H2O
simplify
8H+ + 3H2O2 + Cr2O7^2- --> 3O2 + 2Cr3+ + 7H2O ... acidic net ionic eqn
8H2O + 3H2O2 + Cr2O7^2- --> 3O2 + 2Cr(OH)3 + + 2OH- + 7H2O ... added 8 OH-
simplify
H2O + 3H2O2 + Cr2O7^2- --> 3O2 + 2Cr(OH)3 + 2OH- ... basic net ionic eqn
Molecular equation
3H2O2 + (NH4)2Cr2O7(aq) --> 3O2(g) + 2Cr(OH)3(s) + 2NH3(aq) + H2O
With no source of acid, the solution will be basic, and the chromium in the dichromate will be reduced Cr3+ and chromium(III) hydroxide will precipitate. The final color is due to either an excess of the dichromate ion, or some oxidation of chromium(III) to chromate (CrO4^2-).
Try it with less of the dichromate.
14H+ + Cr2O7^2- + 6e- --> 2Cr3+ + 7H2O.... reduction
-------------------- ------------------- -----------------
14H+ + 3H2O2 + Cr2O7^2- --> 3O2 + 2Cr3+ + 6H+ + 7H2O
simplify
8H+ + 3H2O2 + Cr2O7^2- --> 3O2 + 2Cr3+ + 7H2O ... acidic net ionic eqn
8H2O + 3H2O2 + Cr2O7^2- --> 3O2 + 2Cr(OH)3 + + 2OH- + 7H2O ... added 8 OH-
simplify
H2O + 3H2O2 + Cr2O7^2- --> 3O2 + 2Cr(OH)3 + 2OH- ... basic net ionic eqn
Molecular equation
3H2O2 + (NH4)2Cr2O7(aq) --> 3O2(g) + 2Cr(OH)3(s) + 2NH3(aq) + H2O
With no source of acid, the solution will be basic, and the chromium in the dichromate will be reduced Cr3+ and chromium(III) hydroxide will precipitate. The final color is due to either an excess of the dichromate ion, or some oxidation of chromium(III) to chromate (CrO4^2-).
Try it with less of the dichromate.