What is electrode and half-cell ? Explain symbolic representationby suitable example.

Explanation

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)