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Balance the equation in acidic medium : (a) "When chloride ion" CI^(-)" is oxidised to " CI_(2) " by " MnOoverset(4) (b) "Chlorate ion" CIOoverset(3) "oxidies" Mn^(2+) to MnO_(2)(s) |
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Answer» Solution :(a) The skeleton equation is: `CI^(-)+MnO_(4)rarrCI_(2)+Mn^(2+)` step I. Separation of the equation in two half reactions: (i) Write the O.N of the atoms involvedin the skeleton equation `overset(-1)(CI)^(-)+overset(+7)((Mnoverset(-2)O_(4))^(-)rarroverset(0)CI_(2)+overset(+2)((Mn)^(2+)` (ii) Identify the atoms which undergo change in O.N `overset(-1)(CI)^(-)+(overset(+7)MnO_(4))^(-)rarroverset(0)CI_(2)+overset(+2)(Mn)^(2+)` (III) Find outthe species INVOLVED in the oxidation and reduction half reactions  The tow half reactions are: Oxidation half reaction :L `CI^(-)rarrCI_(2)` Reduction half reactio : `MnO_(4)^(-)rarrCI_(2)+Mn^(2+)` Step II. Balancing of oxidation half reaction : The oxidation half reaction is : `2CIrarrCI_(2)` (i) As the increase in O.N per atom as a result of Oxidation is 1, therefore, add two `e^(-)` on the product side to balance change in O.N. `2CI^(-)rarrCI_(2)+2e^(-)` Thus oxidation half reaction is balanced. Step III Balancing of reduction half reaction: The reduction half reactionis : `CIO_(3)^(-)rarrCI^(-)` (i) As the decrease in O.N is 6, add SIX `e^(-)` on the reactant side to balance change in O.N `CIO_(0)^(-)+6e^(-)rarrCI^(-)` (ii) In order to balance oxygen atoms add three molecules of `H_(2)O` on the product side. Then add `6H^(+)` ions on the reactant side to balance the hyudrogen atoms `CIO_(3)^(-)6H^(+)+6e^(-)rarrCI^(-)+3H_(2)O` The reduction half reaction is balanced. Step IV. ADDING the two half reaction: In order to equyate the electrons,. multiply equation (i) by 3 and add to equation (ii) `({:(""Mn^(2)+2H_(2)OrarrMnO_(2)+4H^(+)+2e^(-)"]"xx3),(CIO_(3)^(-)+6H^(+)+6e^(-)rarrCI^(-)+3H_(2)O):})/(3Mn^(2)^(+)+CIO_(3)^(-)+3H_(2)Orarr3MnO_(2)+6H^(+)+CI^(-))` Step I. Swparation of the equation in two half reactions: (i) Write theO.N of all the atoms involved in the equation: `Toverset(+5)CIoverset(+2)O_(3)^(-)+overset(+2)(Mn)^(2+)rarroverset(+4)Mnoverset(-2)O_(2)+overset(-1)(CI)` (ii) Identify in atoms which undergo change in O.N M `overset(+5)(CIoverset(-2)O_(3))^(-)+overset(+2)(Mn)^(2+)rarroverset(+4)MnO_(2)+overset(-1)(CI)^(-)` (iii) Find out the species involved in the oxidation and reduction half reaction the two hal,f reactions are: oxidtion half reaction : `CIO_(3)rarrCI_(-)` Reduction j half reaction: `CIOO_(3)^(-)rarrCI^(-)` |
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