Faradays laws of electrolysis

Aug 26, 2022, 16:45 IST

About Electrolysis

The process of decomposition of an electrolyte on passing an electric current through its aqueous solution or in the fused state is called electrolysis. An electrolyte (AB) when dissolved in water or when melted dissociates to produce corresponding ions (e.g. A+ and B-). When the circuit is completed by closing key, following reactions occur at the two electrodes.

(a) The cations move towards cathode. On reaching cathode, they gain electrons (supplied by battery) and thus become neutral atoms.(At cathode)    

(b) The anions move towards anode and on reaching the anode they lose electrons and become neutral atom (Atanode) 

B -  → B + e-   ( Oxidation)

Thus electrons from the source (battery) enter the solution (where they are taken up by cations) at the cathode and leave the solution at the anode. As a result, flow of electricity continues Thus electrolysis involves oxidation (de - electronation of the anion) at the anode, and reduction(electronation of cation) at the cathode. 

Note that the above cases are very simple where only dissociation of the salt is considered which is true when the electrolyte is taken in molten state. However, when the aqueous solution of the electrolytes is taken, water also dissociates to a small extent as Thus in such cases two different cations (H+ and   A+   ) and two different anions ( OH-and B- ) are present in solution. Of the two cations, that cation will be liberated at the cathode which has higher reduction potential. Similarly, of the two anions, that anion will be discharged at the anode which has lower reduction potential. The process of electrolysis is further complicated when the electrodes are attacked by the ions of the electrolytes.

Faraday’s second law

When the same quantity of electricity is passed through different electrolytes, the masses of different ions librated at the electrodes are directly proportional to their chemical equivalents weights. Suppose W1  and W2  are the weights of the elements deposited by passing a certain quantity of electricity through their salt solutions and E1 and E2 are 

Find below the detail explanation of Faradays laws of electrolysis