Hello Student ,

Heat and pH have the following effects on Potassium Dichromate

Effect of Heat on K2Cr2O7 (Oxidation State of Cr remains constant)

4K2Cr2O7 ----Heat----> 4K2CrO4 + 2Cr2O3 + 3O2

Effect of pH on K2Cr2O7 (Oxidation State of Cr Remains Constant)

1. Cr2O7^ 2- + H2O ---pH = 8----> CrO4^ 2- + 2H+
2. CrO4^ 2- + 2H+ ---pH = 4----> Cr2O7^ 2- + H2O

Please note the Oxidation number of Cr is constant in both the cases .