Start your trial now! First week only $4.99!*arrow_forward*

BuyFind*launch*

7th Edition

Douglas A. Skoog + 2 others

Publisher: Cengage Learning

ISBN: 9781305577213

Chapter 25, Problem 25.15QAP

Interpretation Introduction

**(a)**

**Interpretation:**

The surface area should be determined in cm^{2}, neglecting the area of the nanotube attachment.

**Concept introduction:**

Surface area of a sphere =

r = radius of the sphere.

Interpretation Introduction

**(b)**

**Interpretation:**

The concentration gradient and the current for A at a concentration of 1.00 mM at different times should be calculated.

**Concept introduction:**

D − diffusion coefficient

t- time after the voltage is applied

r − radius of the sphere

i − time dependent faradaic current

n − number of moles of electrode

F − Faraday constant

A − surface area

D − diffusion coefficient

t- time after the voltage is applied

r − radius of the sphere

Interpretation Introduction

**(c)**

**Interpretation:**

The steady state current should be found

**Concept introduction:**

If r << d, which occurs at long times, the 1/r term predominates, the electron transfer process reaches a steady state. The steady state current only depends on the size of the electrode.

Interpretation Introduction

**(d)**

**Interpretation:**

The time required for the electrode to achieve steady state current following the application of the voltage step should be determined.

**Concept introduction:**

Current should be used for the calculation is 1.01 x steady state value.

D − diffusion coefficient

t- time after the voltage is applied

r − radius of the sphere

i − time dependent faradaic current

n − number of moles of electrode

F − Faraday constant

A − surface area

D − diffusion coefficient

t- time after the voltage is applied

r − radius of the sphere

Interpretation Introduction

**(e)**

**Interpretation:**

The calculations should be repeated for a 3 µm spherical platinum electrode and for a spherical iridium electrode with a surface area of 0.785 mm^{2}

**Concept introduction:**

The formula used:

D − diffusion coefficient

t- time after the voltage is applied

r − radius of the sphere

i − time dependent faradaic current

n − number of moles of electrode

F − Faraday constant

A − surface area

D − diffusion coefficient

t- time after the voltage is applied

r − radius of the sphere

Interpretation Introduction

**(f)**

**Interpretation:**

The results for the three electrodes should be compared and the differences should be discussed.