5. Kinetics of electrode reactions

Current density (equation)

j = I/A

v =I/nFA = j/nF

Standard rate constant (k0)

Quantifies the reversibility of the electron transfer and therefore also the kinetics of the electrode reaction.

The standard rate constant (k0) is determined

when the electrode interface is at equilibrium with a solution in which C*O = C*R

k0 is a measure...

of the ease of electron transfer in a redox reaction

A system with a large k0 will achieve equilibrium ____ and a system with small k0 _______

on a short time scale................... will be sluggish.

Transfer coefficient (α) is a measure....

of the symmetry of the energy barrier

Where does the value for transfer coefficient (α) for most electrochemical reactions lie?

α = 0.3 – 0.7

When a chemical reaction overcomes an activation barrier and passes through a transition state, what usually happens as a result of this

It results in an activation overpotentials for electrochemical reactions

A small value for I0 means that the system is

SLOW and has a large activation-overpotential.

A large value for I0 means that the system is

FAST and has a small activation-overpotential.

If mass transfer is FAST, what limits the reaction

the reaction is limited by electron transfer kinetics