Page 42 - Analytical Electrochemistry 2d Ed - Jospeh Wang

Questions 27

several distinct parts).
3. Use the activated complex theory for explaining clearly how the applied
potential affects the rate constant of an electron-transfer reaction. Draw free
energy curves and use proper equations for your explanation.
4. Use equations to demonstrate how an increase of the stirring rate will effect the
mass transport-controlled limiting current.
5. Derive the Nernst equation from the Butler±Volmer equation.
6. Explain clearly why polyanionic DNA molecules adsorb onto electrode surfaces
at potentials more positive than E , and suggest a protocol for desorbing them
pzc
back to the solution.
7. Which experimental conditions assure that the movement of the electroactive
species is limited by diffusion? How do these conditions suppress the migration
and convection effects?

8. Explain clearly the reason for the peaked response of linear sweep voltammetric
experiments involving a planar macrodisk electrode and a quiescent solution.
9. The net current ¯owing at the equilibrium potential is zero, yet this is a dynamic
situation with equal opposing cathodic and anodic current components (whose
absolute value is i ). Suggest an experimental route for estimating the value of
0
i .
0
10. Explain clearly why only a fraction of the energy shift (associated with a
potential shift) is used for increasing the activation energy barrier.