Question
Question: The correct order of\(Eº_{M^{2 +}/M}\)values with negative sign for the four successive elements Cr,...
The correct order ofEºM2+/Mvalues with negative sign for the four successive elements Cr, Mn, Fe and Co is
A
Mn> Cr > Fe > Co
B
Cr > Fe >Mn> Co
C
Fe >Mn> Cr > Co
D
Cr >Mn> Fe > Co
Answer
Mn> Cr > Fe > Co
Explanation
Solution
Generally across the first transition series, the negative values for standard electrode potential decrease (exception Mn- due to stable d5 configuration)
Standard electrode potential –
Mn Cr Fe Co
M2+/M –1.18 –0.90
0.44 –0.28 eV
So, correct order is Mn > Cr > Fe > Co.