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What is electrode and half-cell ? Explain symbolic representationby suitable example. |
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Answer» Solution :Electrode: In galvanic cell or electrolytic cell, the system generated by putting metal rod or plate in its salt SOLUTIONIS known as electrode, in which flow of current/electrode occur. Half-cell: Electrode and solution in which it is kept, where oxidation or reduction reaction is possible such system is CALLED half-cell. Symbolic representation of electrode (Half-cell): When vertical line is put between metal and its ion and according to the convention for reduction reaction metal ion/metal is to be written. For reduction: Symbolic representation of `Zn^(2+)+2E^(-) to Zn` is `Zn_((aq))^(2+)|Zn_((S))` For oxidation: Symbolic representation of `Zn_((S))toZn^(2+)+2e^-)` is `Zn_((S))|Zn_((aq))^(2+)` If reactant or product is gar or liquid then usually platinum metal is used. symbolic representation of such electrode is as follows: (i) For hydrogen electrode : Anode : `Pt_((S))|H_(2(g))(1" bar")|H_((aq))^(+)` . . . (Oxidation) CATHODE: `H_((aq))^(+)|H_(2(g))(1" bar")Pt`. . . (Reduction) (ii) For bromine electrode: Cathode: `Pt_((S))|Br_(2(aq))|Br_((aq))^(-)`. . . (Reduction) Reaction : `(1)/(2)Br_(2(aq))+E^(-)toBr^(-)`. . . (Reduction) Anode: `Br_((aq))^(-)|Br_(2(aq))|Pt_((S))`. . . (Reduction) Reaction: `Br_((aq))^(-)to(1)/(2)Br_(2(aq))+e^(-)`. . .(Reduction) |
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