Which is the strongest reducing agent among alkali metals?

Options

A. Li
B. Na
C. K
D. Cs

Answer

A

Explanation

The alkali metals have low values of reduction potential and therefore have a strong tendency to lose `e^(-)` and act as good strong reducing agents. The reducing nature increases from sodium to caesium. However lithium is the strongest reducing agent.
The alkali metals have low value of ionization energy which decreases down the group and so can easily lose their valence electron and thus act as good reducing agents.
Li is weakest reducing agent among alkali metals in free state.
Whereas Li acts as strongest reducing agent in solution. Thus, in solution the reducing nature decreases from Li to Na and then increases to Cs.
The greater reducing character of Li than Na is due to its greater hydration energy.
Li being small in size has high ionization energy and due to its small size it is easily hydrated with very high hydration enthalpy. This high hydration enthalpy compensates the high energy required to remove electron.