Question

Using data from Table 11.1, place the following in order of increasing strength as reducing agents (all under standard conditions).

${\mathbf{Cu}}^{\mathbf{+}}\mathbf{,}{\mathbf{F}}^{\mathbf{-}}\mathbf{,}{\mathbf{H}}^{\mathbf{-}}\mathbf{,}{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{,}{\mathbf{I}}_{\mathbf{2}}\mathbf{,}\mathbf{andK}$

Short answer

The increasing order of the strength of reducing agents is given as.

${\text{F}}_2<{\text{H}}_{\text{2}}\text{O}<{\text{I}}_2<{\text{Cu}}^{+}<\text{H}<{\text{K}}^{\text{+}}$

Step-by-step solution

Definition of Oxidation/reduction potential

Oxidation/reduction potential is defined as themeasure of the tendency of a chemical species to gain or lose electrons. The elements with higher reduction potential are goodoxidizing agents and the elements with lower reduction potential are good reducing agents.

Half cell reaction

The potential values are given as,

$\begin{array}{l}{\mathrm{Cu}}^{+}+{\mathrm{e}}^{-}\to \mathrm{Cu},{\mathrm{E}}^0=0.52\mathrm{V}\\ {\mathrm{F}}_2+2{\mathrm{e}}^{-}\to 2{\mathrm{F}}^{-},{\mathrm{E}}^0=2.87\mathrm{V}\\ \mathrm{H}+{\mathrm{e}}^{-}\to {\mathrm{H}}^{-},{\mathrm{E}}^0=-2.23\mathrm{V}\\ {\mathrm{O}}_2+4{\mathrm{H}}^{+}+4{\mathrm{e}}^{-}\to 2{\mathrm{H}}_2\mathrm{O},{\mathrm{E}}^0=1.23\mathrm{V}\\ {\mathrm{I}}_2+2{\mathrm{e}}^{-}\to 2{\mathrm{I}}^{-},{\mathrm{E}}^0=0.54\mathrm{V}\\ {\mathrm{K}}^{+}+{\mathrm{e}}^{-}\to \mathrm{K},{\mathrm{E}}^0=-2.92\mathrm{V}\end{array}$

The species with less standard redox potential value isbetter reducing agent.