Class 12 Chemistry D and F Block Elements Properties of Potassium dichromate

Properties of Potassium dichromate (K2Cr2O7)

Oxidizing properties

Potassium dichromate is a powerful oxidizing-agent in an acidic medium.

Cr2O7 2- + 14H+ + 6 electron --> 2Cr3+ + 7H2O


It oxidizes iodides to iodine.

Cr2O7 2- + 14H+ + 6I- --> 2Cr 3+ + 7H2O + 3I2


It oxidizes ferrous salts to ferric salts.

Cr2O7 2- + 14H+ + 6 Fe2+ --> 2Cr 3++ 7H2O + 6Fe3+


It oxidizes stannous salts to stannic salts.

Cr2O7 2- + 14H+ + 3Sn 2+ --> 2Cr 3+ + 7H2O + 3Sn 4+


It oxidizes H2S to sulphur.

Cr2O7 2- + 8H+ + 3H2S --> 2Cr 3+ + 7H2O + 3S

 

Action of heat

Application of heat leads to the decomposition of Potassium dichromate leading to the formation of potassium chromate, chromic oxide and oxygen.

4K2Cr2O7 -Heat-> 4K2CrO4 + 2CrO3 + 3O2

 

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