How many Faradays of charge are required to convert

1. 1 mole of Mno4 to Mn2+

2. 1 mole of Cr2O7 2- to Cr3+

Hi,

·  The reaction can be represented as:

MnO₄^-   →   Mn²⁺

The oxidation number of Mn in MnO₄^- is +7 and it changes to +2

Hence the 5e^- change has taken place, thus

Quantity of charge required=5F=5×96500=482500F

·  The reaction can be represented as:

Cr₂O₇^2-   →    Cr³⁺

Change in 3e^- charge

Quantity of Charge required =3F=3×96500=289500F

Hope it helps.

Cheers!