Consider the reaction: Cr2O72– + 14H+ + 6e 2Cr3+ + 7H2O. What is the quantity of electricity in coulombs needed to reduce 1 mol of Cr2O72–?

Cr2O72– + 14H+ + 6e 2Cr3+ + 7H2O


For reducing one mole of Cr2O72–, 6 mole of electrons are required. Hence, 6 faraday charge is needed. Hence, 6F = 6×96487 = 578922 C. Thus, the quantity of electricity is needed is 578922 C.


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