Question

Consider the cyclic voltammogram of the ${\mathbf{Co}}^{\mathbf{3}\mathbf{+}}$compoundrole="math" localid="1663646447735" $\mathbf{Co}{\mathbf{\left(}{\mathbf{B}}_{\mathbf{9}}{\mathbf{C}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{11}}\mathbf{\right)}}_{\mathbf{2}}^{\mathbf{-}}$ . Suggest a chemical reaction to account for each wave. Are the reactions reversible? How many electrons are involved in each step? Sketch the sampled current and square wave polarograms expected for this compound.

Cyclic voltammogramofrole="math" localid="1663646461802" $\mathbf{Co}{\mathbf{\left(}{\mathbf{B}}_{\mathbf{9}}{\mathbf{C}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{11}}\mathbf{\right)}}_{\mathbf{2}}^{\mathbf{-}}$ . [Data from W. E. Geiger, Jr., W. L. Bowden, and N. El Murr, "An Electrochemical Study of the Protonation Site of the Cobaltocene Anion and of Cyclopentadienylcobalt(I) Dicarbollides," Inorg. Chem. 1979,18,2358.]

Short answer

The chemical process was linked to waves in a cobalt ion cyclic voltammogram. Cobalt ion cyclic polarograms were sketched.

Step-by-step solution

Definition of Cyclic voltammetry

Cyclic voltammetry can be used to determine the redox behaviour of substances as well as the kinetics of electrode reactions. The cathodic wave dominates the upper section of a cyclic voltammogram. Anodic wave dominates the lowest section of the cyclic voltammogram.

Chemical reaction relates to waves in cyclic voltammogram of cobalt

Reaction sequence occurred in cyclic voltammetry is given as

$\mathrm{Co}\left(\mathrm{III}\right){\left({\mathrm{B}}_9{\mathrm{C}}_2{\mathrm{H}}_{11}\right)}_2^{-}\to \mathrm{Co}\left(\mathrm{II}\right){{\left({\mathrm{B}}_9{\mathrm{C}}_2{\mathrm{H}}_{11}\right)}_2}^{2-}\to \mathrm{Co}\left(\mathrm{I}\right){{\left({\mathrm{B}}_9{\mathrm{C}}_2{\mathrm{H}}_{11}\right)}_2}^{3-}$

From ${\mathrm{E}}_{\mathrm{pa}}$and${\mathrm{E}}_{\mathrm{pc}}$it is obvious that two reduction reactions took place, as depicted above.

The reactions are reversiblebecause the anodic and cathodic peaks are the same. The current sampled is presented as

Figure 1

The polarogram of square wave is drawn as

Figure 2