Question

Explain why Cr²⁺ is strongly reducing while Mn³⁺ is strongly oxidizing.

Answer 1

Cr²⁺ is strong reducing while Mn³⁺ is strongly oxidising. 

E⁰_{Cr³⁺/Cr²⁺} is -0.41 V 

Cr²⁺  + 2e^- → Cr  E° = – 0.91V. 

If the standard electrode potential E° of a metal is large and negative, the metal is a powerful reducing agent because it loses electrons easily. 

Mn → Mn³⁺ + 3e^- 

Mn³⁺ + e^- → Mn²⁺ 

Mn³⁺ [Ar]3d⁴ 

E° = + 1.51 V 

If the standard electrode potential E° of a metal is large and positive, the metal is a powerful oxidising agent because it gains electrons easily.