|
|
ELECTRODE
POTENTIAL OF ZINC
|
||||
|
ELECTRODE
POTENTIAL OF ZINC
|
||||
| In order to determine the electrode potential of zinc a voltaic cell is constructed by a zinc electrode( a zinc strip dipped in 1.00 molar solution of ZnSO4) and hydrogen electrode. Salt bridge is made of potassium chloride (KCl) jelly which completes the circuit between half cells and prevents mixing of solutions. | ||||
|
|
The potentiometer reading gives the E.M.F. of the cell which is 0.76 Volt. Since hydrogen electrode has the potential of 0.00 Volt, hence potential of Zn electrode is 0.76 Volt. | |||
|
0.76
- 0.00 = 0.76 Volt
|
||||
| In external circuit it is observed that the flow of electrons takes place from Zn to H. | ||||
 |
||||
| Thus it concludes that the electrons must have originated from Zn i.e. it is oxidized and it is anode and it is negative with respect to hydrogen electrode. Thus standard reduction potential of zinc is - 0.76V. | ||||
 |
||||
| The standard oxidation potential of zinc is therefore + 0.76V. | ||||
|
Ered = Eox
|
||||
|
-
0.76 Volt = +0.76 Volt
|
||||
| The negative sign shows that the reaction at Zn electrode occurs in the opposite direction and at Zn electrode oxidation takes place not reduction: | ||||
 |
||||
| Reduction takes place on hydrogen electrode: | ||||
 |
||||
|
CELL
REACTION
|
||||
| Adding two equations: | ||||
 |
||||
| For latest information , free computer courses and high impact notes visit : www.citycollegiate.com | ||||