|Class 11 Chemistry Redox Reactions||Standard hydrogen electrode and its application|
Standard hydrogen electrode and its application
Standard hydrogen electrode is the reference electrode that is used to calculate electrode potential of any electrode. It is also called as SHE or NHE.
This apparatus consists of beaker having 1 molar HCL solution. In it, a sealed tube having platinum wire is dipped. This platinum wire is further attached to platinum foil. This complete cell is connected to the cell. Then continuously hydrogen gas maintained at 1 atm is bubbled. Platinum foil here acts as a site of reaction.
The Standard electrode potential of SHE is zero volt. This SHE can act as anode or cathode, depending upon the half cell that is attached to it.
If it acts as cathode then following reaction occurs:
2H+ + 2e- --> H2 (Reduction Occurs)
Hydrogen Ion Hydrogen Gas
If it acts as anode then following reaction occur:
2H - 2e- --> 2H+ (Oxidation occurs)
Hydrogen Gas Hydrogen Ions
Let us calculate the electrode potential of Zn half-cell. The apparatus is set as shown:
We known Zinc is more reactive than hydrogen, that is it has more tendency to loose electrons. Therefore, the following reactions occur:
Likewise, if we calculate it for Copper half cell it comes out to be = 0.34 volt .This fact gave rise electrochemical series