Chapter 18, Problem 18.94QP

Interpretation Introduction

Interpretation:

The standard electrode potential for the given cell has to be found and the diagrammatic representation of the cell has to be given.

Concept Introduction:

Galvanic cell is an electrochemical device in which electrical energy is derived from a chemical reaction.  It has two half cells, oxidation half cell (anode) and reduction half cell (cathode).  The two half cells are connected by a salt bridge.

Redox reactions are the reactions in which both oxidation and reduction takes place simultaneously.  Oxidation is the removal electron from an atom or ion.  Oxidation process increases the oxidation number.  Reduction is the addition of electron to an atom or ion.  Reduction process decreases the oxidation number.  The electrochemical reaction of zinc with copper sulphate is an example of redox reaction.

${\text{Zn}}_{\text{(s)}}{\text{ + CuSO}}_{\text{4}}{}_{\text{(aq)}}\to {\text{ZnSO}}_{\text{4}}{\text{+ Cu}}_{\text{(s)}}$

Standard reduction potential is the measure of the tendency of a species to undergo reduction.  It is measured in terms of volts.  The substance which is having high positive value will easily undergo reduction.  In electrochemical series, the elements are arranged in the decreasing order of reduction potential.

The standard electrode potential of a cell ${\text{(E}}^{°}{}_{\text{cell}})$ is the difference in electrode potential of the cathode and anode.

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