Question

Lithium is the strongest reducing agent though it has the highest ionization energy in its group. Which of the following factors is responsible for making $\mathrm{Li}$ the strongest reducing agent?

• A. Large heat of atomisation
• B. Smaller size
• C. Large sublimation energy
• D. Large amount of hydration enthalpy

Answer 1

Answer: (B), (D)

Large amount of hydration enthalpy

Explanation for the Correct Option:

Option(D): A large amount of hydration enthalpy

• Hydration energy is basically known as the amount of energy released when one mole of ions undergoes hydration.
• Lithium-ion has a smaller size and thus, it can attract a large number of water molecules.
• Hence Several water molecules can surround Lithium cation which gives rise to a large amount of hydration energy.
• Therefore, a large amount of hydration energy makes lithium the strongest reducing agent although it has the highest ionization enthalpy which generally tends to decrease the reducing property.

Option(B): Smaller size

• Lithium-ion has a smaller size, which helps in explaining its strongest reducing property of it.

Explanation for the incorrect Option:

Option(A): Large heat of atomization

• The heat of atomization is known as the enthalpy change that accompanies the total separation of all atoms in a chemical substance.
• Large heat of atomization does not explain the strongest reducing property of Lithium.
• Hence, the given option is the incorrect one.

Option(C): Large sublimation energy

• The sublimation energy is basically referred to as the heat required to change one mole of a substance from a solid-state to a gaseous state at a constant temperature and pressure.
• Large sublimation energy does not explain the strongest reducing property of Lithium.
• Thus, the given does not coincide with the correct concept.

Hence, the factor responsible for making $\mathrm{Li}$ the strongest reducing agent is: large amount of hydration enthalpy.