Plz explain the trends of M^2+/M and M^3+/M^2+ standard electrode potentials of D-block elements. And also explain as to what they signify.

Asked by Manav Rajput | 20th Nov, 2010, 12:55: AM

Expert Answer:

M..................>M2+
M2+...............>M3+
The above equations signifies the standard electrode potentials of some half–cells involving 3d-series of transition elements and their ions in aqueous solution, 

Electrode potential for a Mn+/M half-cell is a measure of the tendency for the reaction, Mn+(aq) + ne– → M(s)

Look out at this series:

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.

Answered by  | 20th Nov, 2010, 08:32: AM

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