Chapter 19, Problem 98IAE

Interpretation Introduction

(a)

Interpretation:

An equation for the temperature variation of E⁰_cell should be derived.

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.

Also,

$\Delta G^0=\Delta H^0-T\Delta S^0$

Here, $\Delta H^0$ is standard enthalpy change of the reaction, T is temperature and $\Delta S^0$ is standard entropy change.

Interpretation Introduction

(b)

Interpretation:

The cell potential of a Daniel cell at 50⁰C under standard conditions should be determined.

Concept introduction:

The cell reaction for a Daniel cell is ${\text{Zn(s) + Cu}}^{2+}\text{(aq) }\to {\text{ Zn}}^{2+}\text{(aq) + Cu(s)}$

The value of E_cellunder non-standard conditions can be determined by Nernst equation.

$\text{E}={\text{E}}^0-\frac{2.303RT}{nF}\log Q$

Here,

E − cell potential

E⁰ − standard cell potential

R − universal gas constant

T − temperature in Kelvin

n − number of electrons transferred

F − Faraday constant

Q − reaction quotient