Question
Explain trends in $M^{2+}/M$ standard electrode potentials.
✓
Answer
$\rightarrow$ An element in $M^{2+}$ state in aqueous medium is more stable if the electrode potential $(M^{2+}/M)$ value is more negative.
$\rightarrow$ The general trend towards less negative $ E^Θ$ values across the series is related to the general increase in the sum of the first and second ionization enthalpies.
$\rightarrow$ The unique behaviour of $Cu,$ having a positive $EV,$ accounts for its inability to liberate $H_2$ from acids. Only oxidising acids $($nitric and hot concentrated sulphuric$)$ react with $Cu,$ the acids being reduced.
$\rightarrow$ It is interesting to note that the value of $EV$ for $Mn, Ni$ and $Zn$ are more negative than expected from the trend.
$\rightarrow$ The general trend towards less negative $ E^Θ$ values across the series is related to the general increase in the sum of the first and second ionization enthalpies.
$\rightarrow$ The unique behaviour of $Cu,$ having a positive $EV,$ accounts for its inability to liberate $H_2$ from acids. Only oxidising acids $($nitric and hot concentrated sulphuric$)$ react with $Cu,$ the acids being reduced.
$\rightarrow$ It is interesting to note that the value of $EV$ for $Mn, Ni$ and $Zn$ are more negative than expected from the trend.
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