Question

Four successive members of the first row transition elements are listed below with atomic numbers. Which one of them is expected to have the highest ${E^{0}}_{M^{3 +}/M^{2 +}}$value?

• A. Cr(Z = 24)
• B. Mn(Z = 25)
• C. Fe(Z = 26)
• D. Co(Z = 27)

Answer 1

Answer: (D)

Co(Z = 27)

Answer 2

E⁰Cr3+/Cr2+ = – 0.41 V ; E⁰Mn3+/Mn2+ = + 1.57 V ; E⁰Fe3+/Fe2+ = + 0.77 V ; E⁰Co3+/Co2+ = + 1.97 V

SRP value normaly increases from left to right in the period of d-block elements. Some SRP value are exceptionally higher due to stability of product ion. For e.g. E⁰Mn3+/Mn2+ = + 1.57 V ; E⁰Co3+/Co2+ = + 1.97 V.