Question

The configuraton of both Cr²⁺ and Mn³⁺ is d<sup.4 but Cr²⁺ is reducing agent and Mn³⁺ is oxidising agent. Give reason.

Answer 1

E^o value for Cr³⁺ / Cr²⁺ is negative (-0.41. V) whereas E^o value for Mn³⁺ / Mn²⁺ is positive (+ 1.57V). Hence Cr²⁺ ions can easily undergo oxidation to give Cr³⁺ ions and therefore, acts as strong reducing agent. On the other hand Mn³⁺ can easily undergo reduction to give Mn²⁺ and hence acts as oxidising agent.