140. Solving a chemistry problem

9. A sample of ore weighing m g was dissolved and iron was reduced to Fe2 +, and then it was quantitatively oxidized in a coulometric cell on a platinum anode at a controlled potential. The amount of electricity consumed was determined with a coulometer consisting of a platinum anode immersed in a KI solution. The titration of iodine released during the passage of the current required V ml of 0.0500 M Na2S203.
Calculate the mass fraction (%) of iron in the ore:
Option 1
m, g 0.7905
V, ml 22.30