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Redox reactions play a pivotyal role in chemistry and biology. The values of standard redox potential (E^(@)) of two half-cell reactions decidewhich way the reaciton is expected to proced. A simple exampler is a Daniel cell in which zinc goes into solution and copper gerts deposited. Given below are a set of half-cell reactions (acidic medium) along with theirE^(@) (V with respect to normal hydrofgen electrode) values. Using this data : I_(2) + 2e^(-) rarr 2I^(-)"" E^(@) = 0.54, CI_(2) + 2e^(-) rarr 2CI^(-) ""E^(@) = 1.36, .Mn^(3+) + e^(-) rarr Mn^(2+) ""E^(@) = 1.50, Fe^(3+) + e^(-) rarr Fe^(2+)"" E^(@) = 0.77, O_(2) + 4H^(+) + 4e^(-) rarr 2H_(2)O ""E^(@) = 1.23, Soldium fusion extract, obtained from aniline, on treatment with iron (II) sulphatge and H_(2)SO_(4) in presence of airgives a Prussion buleprecipitate. The blue colour is due to the formation of : |
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Answer» `Fe_(4)[Fe(CN)_(6)]_(3)` `Fe^(2+) + 6CN^(-) rarr [Fe(CN)_(6)]^(4-)` `4Fe^(3+) + 3[Fe(CN)_(6)]^(4-) rarr underset("Prussion blue")(Fe_(4)[Fe(CN)_(6)]_(3darr)` |
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