Quiz 8

Tafel equation:

The transfer coefficients reflect the linear dependence of the activation energy

of the cathodic and anodic processes on

• the change in galvanic potential at the interface of the metal/solution

• the fraction of electrons that is transferred in the slowest stage

• the mass transfer stage

The Tafel equation is always valid if:

• the Butler-Volmer equation is satisfied

Given α = 0.15, calculate β.

• -0.85

• 0.15

• 0.85

• -0.15

• 0.5

The minimum dependence of I of electroreduction of S₂O₈^2- on E is related to

• decrease in the surface concentration of anions

• increase in the activation energy of the process

• decrease in the bulk concentration of anions

• slowed mass transfer

In the Butler-Volmer equation, the second exponential can be neglected if

• η > >25 mV

• η << 25 mV

• t = 0^oC

The equilibrium potential for the reaction Cu²⁺ + 2e = Cu is 0.1 V. What current will be registered at Pt electrode at E = 0 V?

• negative

• positive

• zero

An ideally polarizable electrode:

Under low overpotential conditions, which factor does NOT influence the exchange current of the reaction Ox⁺ + e⁻ ⇌ Red?

• temperature

• concentration of Ox

• electrode material

• electron transfer rate constant

• electrode potential

Calculate the coefficient b of the Tafel equation if α=0.5, t=25^oC, n=1

• 0.118

• 0.051

• 0.028

• 0.236