Question

Standard Eo values are Fe2+/Fe = -0.44 V, Fe3+/Fe2+ = 0.77 V. If Fe2+, Fe3+ and Fe blocks are kept together, then (a) Fe2+ decreases (b) Fe3+increases (c) Fe3+ decreases (d) Fe increases

Answer 1

Explanation:

Electronic configuration of Mn is [Ar] 4s2 3d5 and Configuration of iron [Ar] 4s2 3d5.

Mn3+ + 3e– → Mn2+

(more spontaneous due to higher stability of Fe3+) Fe3+ + e– → Fe2+

(less spontaneous due to higher stability of Fe3+)

Due to stability of half filled d-orbitals, Mn2+ is more stable than Mn3+ and thus its reduction is more spontaneous. Similarly Fe3+ is more stable than Fe2+ and thus its reduction is less spontaneous.