Chapter 19, Problem 85IAE

Interpretation Introduction

(a)

Interpretation:

The value ofE⁰_cell should be determined.

Concept introduction:

In the special case in which the reactants and products are in their standard states; the standard Gibbs energy change per mole of reaction is given by the following relation:

${\text{Δ}}_{\text{r}}{\text{G}}^{\text{0}}{\text{ = -zFE}}^{\text{0}}{}_{\text{cell}}$

Here, z is number of electrons transferred, F is Faraday’s constant and ${\text{E}}^{\text{0}}{}_{\text{cell}}$ is standard electrode potential of cell.

For a reaction, the Gibbs free energy can also be calculated as follows:

${\text{Δ}}_{\text{r}}{\text{G}}^{\text{0}}$ = ${\text{ΔG}}^{\text{0}}$ (products) - ${\text{ΔG}}^{\text{0}}$ (reactants)

Interpretation Introduction

(b)

Interpretation:

The value of E⁰ for the reduction of CO₂ into methanol should be calculated.

Concept introduction:

In an electrochemical cell, there are two electrodes that can be observed.

If oxidation takes place on an electrode, that electrode is called anode. The species in that electrode remove electrons and itself gets oxidized.

If reduction takes place on an electrode, that electrode is called cathode. The species in that electrode absorbs electrons and itself gets reduced.

The electrode potential of cell can be calculated as follows:

$E^0{}_{\text{cell}}=E^0{}_{\text{cathode}} -E^0{}_{\text{anode}}$