CBSE Class 12-science Answered
Electrode potential for a Mn+/M half-cell is a measure of the tendency for the reaction, Mn+(aq) + ne– → M(s)
Standard electrode potentials for 3d-elements
Elements |
Ion |
Electrode reaction |
E°/ volt |
Sc |
Sc3+ |
Sc3++ 3e– Sc |
– 2.10 |
Ti |
Ti2+ |
Ti2++ 2e– Ti |
– 1.60 |
V |
V2+ |
V2++ 2e– V |
– 1.20 |
Cr |
Cr3+ |
Cr3+ + 3e– Cr |
– 0.71 |
Mn |
Mn2+ |
Mn2++ 2e– Mn |
– 1.18 |
Fe |
Fe2+ |
Fe2+ + 2e– Fe |
– 0.44 |
Co |
Co2+ |
Co2+ + 2e– Co |
– 0.28 |
Ni |
Ni2+ |
Ni2+ + 2e– Ni |
– 0.24 |
Cu |
Cu2+ |
Cu2+ + 2e– Cu |
+ 0.34 |
Zn |
Zn2+ |
Zn2+ + 2e– Zn |
– 0.76 |
The above transition series expalin the trends of d- block elements in which the negative values of E° for the first series of transition elements (except for Cu2+/ Cu ) indicate that metals should liberate hydrogen from dilute acids i.e., the reactions.