Question #d0f6f

1 Answer
Aug 30, 2017

This is a redox reaction (and we will see why!), and we separate the reaction into individual oxidation reduction couples.......

Explanation:

Oxidation reaction: Fe(II) is OXIDIZED to Fe(III)

FeI2Fe3++2I+e (i)

Reduction reaction: Iodate ion is REDUCED to I+I

V+IO3+6H++4eI++3H2O (ii)

And for each half equation, charge and mass are balanced ABSOLUTELY, as indeed they must be if we purport to represent chemical reality. I add them in such a way as to eliminate the electrons from the final equation, i.e. 4×(i)+(ii):

4FeI2+IO3+6H+4Fe3++8I+I++3H2O

And this is in fact balanced with respect to mass and charge. But we could add 1×Cl to each side of the chemical equation....

4FeI2+IO3+6H++Cl4Fe3++8I+ICl+3H2O

And to make it even simpler, I could remove 8×I FROM EACH SIDE of the EQUATION:

4Fe2++IO3+6H++Cl4Fe3++ICl+3H2O,

i.e. a four electron reduction with respect to IO3, and a four electron oxidation with respect to 4 equiv of ferrous ion.