Chapter 19, Problem 2STP

Interpretation Introduction

Interpretation:

Half cell reactions are to be written for a given redox reaction.

Concept introduction:

A redox reaction is a combination of oxidation half reaction and reduction half reaction.

Oxidation half reaction involves loss of electrons and reduction half reaction involves gain of reaction. Both processes occur simultaneously.

Answer to Problem 2STP

C

Explanation of Solution

The given chemical equation is:

$Ni+CuC{l}_2\to NiC{l}_2+Cu$

The oxidation number of the atoms involved in chemical equation is:

$\stackrel{0}{Ni}+\stackrel{+2}{Cu}{\stackrel{0}{Cl}}_2\to \stackrel{+2}{Ni}{\stackrel{0}{Cl}}_2+\stackrel{0}{Cu}$

Thus oxidation number shows that

$Ni$ is oxidized to $NiC{l}_2$ and $CuC{l}_2$ is reduced to $Cu$

Change in oxidation number of $Ni=+2$

Change in oxidation number of $C{u}^{+2}=-2$

Therefore,

Oxidation half reaction:

$Ni\to N{i}^{+2}+2e^{-}$

Reduction half reaction:

$C{u}^{+2}+2e^{-}\to Cu$

Conclusion

Thus, oxidation half reaction contains the species which involves loss of electrons and reduction half reaction involves the species which involves gain of electrons.

Thus option C is correct and others are incorrect.