in the external circuit. . . Galvanic cell notation The galvanic cell is represented by a cell diagram, for example, Daniel cell is represented as Zn (s) Zn (aq) Cu (aq) Cu (s) + + In the above notation, a single vertical bar (|) represents a phase boundary and the double vertical bar (||) represents the salt bridge.
The anode half cell is written on the left side of the salt bridge and the cathode half cell on the right side. The anode and cathode are written on the extreme left and extreme right, respectively. The emf of the cell is written on the right side after cell diagram. XII U9 Electro XII U9 Electro - - - - Phase boundary Phase boundary + + Zn (s) Zn (aq) Cu (aq) Cu (s) .1V Anode Cathode Standard emf of the cell (extreme Lef) (extreme right) Anode half cell Lef Salt bridge Right Cathode Half cell Example The net redox reaction of a galvanic cell is given below Cr (s) + 3Cu (aq) 2Cr (aq) + 3Cu (s) + + Write the half reactions and describe the cell using cell notation.
Anodic oxidation 2Cr (s) 2Cr (aq) + 6e + .....( ) Cathodic reduction : 3Cu (aq) + 6e Cu (s) + - → .....( ) Cell Notation is + + Cr (s) Cr (aq) Cu (aq) Cu(s) . . emf of a Cell We have learnt that when two half cells of a Daniel cell are connected, a spontaneous redox reaction will take place which results in the flow of electrons from anode to cathode. The force that pushes the electrons away from the anode and pulls them towards cathode is called the electromotive force (emf) (or) the cell potential.
The SI unit of cell potential is the volt (v). When there is one volt difference in electrical potential between the anode and cathode, one joule of energy is released for each columb of charge that moves between them. i.e., 1J = 1C 1V .....( . ) The cell voltage depends on the nature of the