Question

On the basis of the standard electrode potential values stated for acid solutions, predict whether Ti⁴⁺ species may be used to oxidise Fe(II) to Fe(III)
Ti⁴⁺ + e⁻ → Ti³⁺, E⁰= +0,01V
Fe³⁺ + e⁻ → Fe²⁺, E⁰= +0,77V

Answer 1

Concept : The element which has greater reduction potential gets reduced easily while the element with the lower reduction potential will get easily oxidised.

         Here, reduction potential of Ti⁴⁺ is +0.01V. and reduction potrn of Fe³⁺ is +0.077V

Here it is clear that, reduction potential of Ti⁴⁺ Is lower than reduction potential of Fe³⁺. Hence, it cannot be reduced in comparison with Fe³⁺/Fe²⁺ .

Hence it is clear that, Ti⁴⁺ cannot oxidise Fe²⁺ to Fe³⁺

Answer 2

Ti⁴⁺ + e⁻ → Ti³⁺, E⁰= +0.01V

Fe³⁺ + e⁻ → Fe²⁺, E⁰= +0.77V

The element having higher standard electrode potential will be reduced first with respect to another one.Here iron has higher standard reduction potential and hence it will readily be reduced and Ti will be oxidised.

For Ti⁴⁺ oxidise Fe(II) to Fe(III),the cell potential will be

E(cell)=E(red)-E(ox)        (in standard state)

         =0.01-0.77

         =-0.76

If cell poential becomes negetive, del G becomes positive.This reaction cannot be happened.Hence Ti⁴⁺ species may not be used to oxidise Fe(II) to Fe(III)