Describe the electrolysis of molten NaCl using inert electrodes.

Explanation

Let us understand the function of a electrolytic cell by considering the electrolysis of molten sodium chloride.
The electrolytic cell consists of two iron electrodes dipped in molten sodium chloride and they are connected to an external DC power supply via a key as shown in the figure. The electrode which is attached to the negative end of the power supply is called the cathode, and the one which attached to the positive end is called the anode. Once the key is closed, the external DC power supply drives the electrons to the cathode and at the same time pull the electrons from the anode.
Cell reactions :
`Na^(+)` ions are attracted towards cathode, where they combines with the electrons and reduced to liquid sodium.
Cathode (reduction)
`Na^(+)(l)+e^(-) rarr Na(l) " "E^(@)=-2.71V`
Similarly, `Cl^(-)` ions are attracted towards anode where they losses their electrons and oxidised to chlorine gas.
Anode (oxidation)
`2Cl^(-)(l) rarr Cl_(2)(g)+2e^(-) " "E^(@)=-1.36V`
The overall reaction is,
`2Na^(+)(l)+2Cl^(-)(l) rarr 2Na(l)+Cl_(2)(g) " "E^(@)=-4.07V`
The negative `E^(@)` value shows that the above reaction is a non-spontaneous one. Hence, we have to supply a voltage greater than 4.07V to cause the electrolysis of molten NaCl.