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Question
Why EΘ values for Mn, Ni and Zn are more negative than expected?
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Solution
Negative E° values of Mn2+ and Zn2+ are because of stabilities of half-filled (3d10 : Mn2+) and fully-filled (3d10 : Zn2+) configuration respectively.Mn2+ ion has higher EΘ value because of highest negative enthalpy of hydrogen.
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RELATED QUESTIONS
Which of the following cations are coloured in aqueous solutions and why ?
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Account for the following:
Zn is not considered as a transition element.
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| Cr2+/Cr | −0.9 V |
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| Cr3/Cr2+ | −0.4 V |
| Mn3+/Mn2+ | +1.5 V |
| Fe3+/Fe2+ | +0.8 V |
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