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How much is the oxidising power of the MnO_4^(-) (1M)|Mn^(2+) (1M) couple decreased if the H^+ concentration is decreased from 1M to 10^-4 M at 25^@C |
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Answer» Solution :The HALF cell REACTION is `MnO_4^(-) +8H^+ +5e=Mn^(2+)+4H_2O` Let us suppose that only the `H^+` concentration deviates from 1mole`//` litre `E_(MnO overline4. Mn^(2+))=E_(MnO_4^-,Mn^(2+))- 0.0591/2 log""([Mn^(2+)])/([MnO_4^-][H^+]^8)` `E-E^@=-0.0118 log""((1))/((1)(10^-4)^8)=-0.38` volt The couple `MnO_4^-//Mn^(2+)` has thus moved down by 0.38 volt from its standard value i.e to a position of less oxidising POWER. |
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