Question

Among alkali metals , why is lithium regarded as most apt reducing in aqueous solutions?

Answer 1

The chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr) make up the alkali metals (Fr). They make up group 1, which is located in the s-block of the periodic table, along with hydrogen. The outermost electron of all alkali metals is in an s-orbital configuration; as a result of this shared electron configuration, their distinctive characteristics are remarkably similar.

Complete answer:
Because of their high tendency to lose electrons, alkali metals are excellent reducing agents. From Na to Cs, the decreasing character rises.
Due to its higher hydration energy, Li is a more powerful reducing agent than Na.
The ionisation energy of an element that functions as a reducing agent must be low. Because of their low ionisation energies, alkali metals are powerful reducing agents. The lowering property rises in the same sequence as the ionisation decreases from Li to Cs. Thus, among alkali metals in the free gaseous form, Li is the weakest reducing agent, whereas Cs is the strongest.
The standard oxidation potential value ${{E}^{o}}_{ext}$ is used to determine an element's ability to lose electrons in solution. Alkali metals are powerful reducing agents because of their high ${{E}^{o}}_{ext}$ values. However, Li is the most powerful reducing agent in solution among alkali metals, since its ${{E}^{o}}_{ext}$ value is the highest.
At first glance, lithium, being the alkali metal with the highest ionisation energy, appears to be the most powerful reducing agent in solution. This is understandable once we realise that ionisation energy is a characteristic of an isolated atom in a gaseous state, whereas oxidation potential is concerned when a metal atom enters a solution.
Lithium has a high ionisation enthalpy due to its tiny size. However, because of its tiny size, it is well hydrated and has a very high hydration enthalpy. The high enthalpy of hydration compensates for the considerable energy required to remove electrons (in the second step). As a result, Li has a higher tendency than other alkali metals to lose electrons in solution. As a result, Li is the most powerful reducing agent.

Note:
Lithium is an element with the atomic number 3 and the symbol Li. It's a silvery-white alkali metal that's pleasant to the touch. It is the lightest metal and the lightest solid element under normal circumstances. Lithium, like all alkali metals, is very reactive and combustible, thus it must be kept in a vacuum, inert environment, or inert liquid like refined kerosene or mineral oil.