Question

Rank these species by their ability to act as an oxidizing agent. Best oxidizing agent

Answer 1

Concepts and reason

Electrochemical series provide important data about the reduction/oxidation potential of various elements.

Rank the species in their ability to act as an oxidising agent.

Fundamentals

Reduction is the gain of electron, while oxidation is the loss of electron.

An oxidising agent is a species which oxidises other and itself get reduced.

A reducing agent is a species which reduces other species and itself get oxidised.

Electrochemical series enlist the species in the increasing order of their reduction potentials in downward direction.

A species with higher and positive value of electrode reduction potential tend to undergo reduction quickly and act as a strong oxidising agent.

Consider the following species,

${\rm{C}}{{\rm{r}}^{2 + }},\,{\rm{B}}{{\rm{r}}_{\rm{2}}}{\rm{,}}\,{\rm{N}}{{\rm{i}}^{2 + }},\,{\rm{C}}{{\rm{a}}^{2 + }}$

The reduction potential for the following species is as follows:

$\begin{array}{l}\\{\rm{C}}{{\rm{r}}^{2 + }}\left( {aq} \right) + 2{{\rm{e}}^ - } \to {\rm{Cr}}\left( s \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,E^\circ = - 0.91\,{\rm{V}}\\\\{\rm{B}}{{\rm{r}}_{\rm{2}}}\left( {aq} \right){\rm{ + 2}}{{\rm{e}}^ - } \to {\rm{2B}}{{\rm{r}}^ - }\left( {aq} \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,E^\circ = + 1.09\,{\rm{V}}\\\\\,{\rm{N}}{{\rm{i}}^{2 + }}\left( {aq} \right) + 2{{\rm{e}}^ - } \to {\rm{Ni}}\left( s \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,E^\circ = - 0.23\,{\rm{V}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\\\\\,{\rm{C}}{{\rm{a}}^{2 + }}\left( {aq} \right) + 2{{\rm{e}}^ - } \to {\rm{Ca}}\left( s \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,E^\circ = - 2.76\,{\rm{V}}\\\end{array}$

The decreasing order of species acting as oxidising agent is as follows:

Ans:

The decreasing order of species acting as oxidising agent is as follows: