Chapter 19, Problem 19.117QP

Interpretation Introduction

Interpretation:

The electrodes and movement of electrons along the wires and cations and anions in solution has to be labelled.

Concept introduction:

Conventional notation for representing Galvanic cell:

The single vertical line represents a phase boundary. The double vertical line denotes the salt bridge. Anode is written first to the left of the double lines, and the cathode is written to the right of the double lines. The electron is moving from Anode to cathode. At anode oxidation process occurs and at cathode reduction process occurs.

Standard reduction potential: The voltage associated with a reduction reaction at an electrode when all solutes are 1M and all gases are at 1 atm. The hydrogen electrode is called the standard hydrogen electrode (SHE).

Standard emf: ${\text{E}}_{cell}^0$ is composed of a contribution from the anode and a contribution from the cathode is given by,

$E_{cell}^o=E_{cathode}^o-E_{anode}^o$

Where both $E_{cathode}^o$ and $E_{anode}^o$ are the standard reduction potentials of the electrodes.

Electrolysis: The process in which electrical energy is used to cause a non-spontaneous chemical reaction to occur. An electrolytic cell is an apparatus for carrying out electrolysis.

In a spontaneous reaction standard emf of a reaction is positive; if the value if negative then it is non-spontaneous and external energy (electrical energy) is applied to carry out that reaction.

During electrolysis, cations are reduced at cathode and anions are oxidized at anode. And in aqueous solutions water itself may be oxidized and/or reduced depends on the nature of other species involved/ present.