Consider the reactions,

$\text{ I. }{\mathrm{H}}_3{\mathrm{PO}}_2\left(\mathrm{aq}\right)+4{\mathrm{AgNO}}_3\left(\mathrm{aq}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)⟶{\mathrm{H}}_3{\mathrm{PO}}_4\left(\mathrm{aq}\right)+4\mathrm{Ag}\left(\mathrm{s}\right)+4{\mathrm{HNO}}_3\left(\mathrm{aq}\right)$

$\text{ II. }{\mathrm{H}}_3{\mathrm{PO}}_2\left(\mathrm{aq}\right)+2{\mathrm{CuSO}}_4\left(\mathrm{aq}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)⟶{\mathrm{H}}_3{\mathrm{PO}}_4\left(\mathrm{aq}\right)+2\mathrm{Cu}\left(\mathrm{s}\right)+2{\mathrm{H}}_2{\mathrm{SO}}_4\left(\mathrm{aq}\right)$

$\text{ III. }{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{CHO}\left(\mathrm{l}\right)+2{\left[\mathrm{Ag}{\left({\mathrm{NH}}_3\right)}_2\right]}^{+}\left(\mathrm{aq}\right)+3{\mathrm{OH}}^{-}\left(\mathrm{aq}\right) ⟶{\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{COO}}^{-}\left(\mathrm{aq}\right)+2\mathrm{Ag}\left(\mathrm{s}\right) +4{\mathrm{NH}}_3\left(\mathrm{aq}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

$\text{ IV. }{\mathrm{C}}_6{\mathrm{H}}_5\mathrm{CHO}\left(\mathrm{l}\right)+2{\mathrm{Cu}}^{2+}\left(\mathrm{aq}\right)+5{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)⟶\text{ No change observed }$

What inference do you draw about the behaviour of ${\mathrm{Ag}}^{+}\text{and }{\mathrm{Cu}}^{2+}$from these reactions?

 

In (a) and (b) reactions, ${\mathrm{AgNO}}_3\text{ and }{\mathrm{CuSO}}_4$ act as ' oxidizing agents respectively. They oxidize ${\mathrm{H}}_3{\mathrm{PO}}_2$ (hypo phosphorous acid) to ${\mathrm{H}}_3{\mathrm{PO}}_4$ (orthophosphoric acid). In reaction (c) ${\left[\mathrm{Ag}{\left({\mathrm{NH}}_3\right)}_2\right]}^{+}$ oxidizes benzaldehyde to benzoic acid but in reaction (d), ${\mathrm{Cu}}^{2+}$ do not oxidize benzaldehyde (${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{CHO}$) to benzoic acid. This indicates that ${\mathrm{Ag}}^{+}$ is a stronger oxidizing agent than ${\mathrm{Cu}}^{2+}$.