Which is a Stronger Reducing Agent Cr2+ Or Fe2+ And Why? - Chemistry

Which is a stronger reducing agent Cr2+ or Fe2+ and why?

Solution 1

The following reactions are involved when Cr2+ and Fe2+ act as reducing agents.

Cr^(2+) -> Cr^(3+)Fe^(2+) -> Fe^(3+)

The  E_((Cr^(3+))/(Cr^(2+)))^@ value is -0.14 V and E_(" "(Fe^(3+))/(Fe^(2+)))^@ is + 0.77 V. This means that Cr2+ can be easily oxidized to Cr3+, but Fe2+ does not get oxidized to Fe3+ easily. Therefore, Cr2+ is a better reducing agent that Fe3+.

Solution 2

Cr2+ is a stronger reducing agent than Fe2+. This is because E°(Cr3+/Cr2+) is negative (- 0.41V) whereas E°(Fe3+/Fe2+) is positive (+ 0.77 V). Thus, Cr2+ is easily oxidised to Fe3+ but Fe2+ cannot be easily oxidised to Fe3+.

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APPEARS IN

NCERT Class 12 Chemistry Textbook
Chapter 8 The d-block and f-block Elements
Q 7 | Page 220