On the basis of the standard electrode potential values stated for acid solution, predict whether Ti$^{4+}$ species may be used to oxidise Fe(II) to Fe(III): $$\mathrm{Ti^{4+}}+e^-\longrightarrow\mathrm{Ti^{3+}};\quad E^{\circ}=+0.01\ \mathrm{V}$$ $$\mathrm{Fe^{3+}}+e^-\longrightarrow\mathrm{Fe^{2+}};\quad E^{\circ}=+0.77\ \mathrm{V}$$

CBSE Class 12 · 2007 · Redox Reactions and ElectrochemistryShort Answer

On the basis of the standard electrode potential values stated for acid solution, predict whether Ti

^{4 +}

species may be used to oxidise Fe(II) to Fe(III):

T i^{4 +} + e^{-} ⟶ T i^{3 +}; E^{\circ} = + 0.01 V

F e^{3 +} + e^{-} ⟶ F e^{2 +}; E^{\circ} = + 0.77 V

Answer: No. For Ti⁴⁺ + Fe²⁺ → Ti³⁺ + Fe³⁺, E°_cell = 0.01 − 0.77 = −0.76 V < 0, so the reaction is non-spontaneous.

For Ti

^{4 +}

to oxidise Fe

^{2 +}

, the reaction would be

T i^{4 +} + F e^{2 +} ⟶ T i^{3 +} + F e^{3 +}

E_{ce l l}^{\circ} = E_{c a t h o d e}^{\circ} - E_{an o d e}^{\circ} = 0.01 - 0.77 = - 0.76 V

Since

E_{ce l l}^{\circ} < 0

(

Δ G^{\circ} > 0

), the reaction is non-spontaneous —

Ti^{4 +} cannot oxidise Fe(II) to Fe(III)

CBSE Class 12 Board · 2007 · Subjective