Question

If it is shown that titanium can be used as a sacrificialanode to protect iron, what conclusion can be drawn aboutthe standard reduction potential of its half-reaction?

$\mathit{T}{\mathit{i}}^{\mathbf{3}\mathbf{+}}\left(aq\right)\mathbf{+}\mathbf{3}{\mathbf{e}}^{\mathbf{-}}\mathbf{\to }\mathit{T}\mathit{i}\left(s\right)$

Short answer

Standard reduction potential in reduction of ${\mathrm{Ti}}^{3+}$ to $\mathrm{Ti}$ is more negative than the standard potential in the reduction of ${\mathrm{Fe}}^{2+}$ to $\mathrm{Fe}$.

Step-by-step solution

Reactivity series

The reactivity series depicts the arrangement of metals based on their reactivity according to their standard reduction potentials. The reduction potential of hydrogen is kept at the center. The metals on top of hydrogen tend to reduce and have positive reduction potentials. The metals on the bottom tend to oxidize and have negative reduction potentials.

Step 2: Standard reduction potential of half-reaction

It is given that the titanium metal is used as a sacrificial anode to protect the iron. It indicates that titanium is more oxidized than iron. When solid titanium oxidizes to aqueous ${\mathrm{Ti}}^{3+}$, the standard reduction potential for the reduction of ${\mathrm{Ti}}^{3+}$ to $\mathrm{Ti}$ is more negative than that of ${\mathrm{Fe}}^{2+}$ to $\mathrm{Fe}\left(-0.409\mathrm{V}\right)$.