Explain phenomenon of polarisation and how it can be eliminate | Applied Electrochemistry | Physical
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- Опубликовано: 9 сен 2024
- When the electric current is passed between Pt electrodes which are placed in dil. H2SO4. H2 and O2 gases are liberated at cathode and anode respectively.
If now battery is removed and the two electrodes are connected with galvanometer a small current will be seen to flow between two electrodes. The direction of the current is opposite to that during the electrolysis.
It so happens because during the electrolysis Pt electrodes gets covered with the bubbles of H2 and O2 and so these electrodes become gas electrodes and both will form the electrochemical cell. This electrochemical cell has some fixed value of emf. The direction of this emf is opposite to the current from battery. This phenomenon of back emf due to the product of the electrolysis is known as polarisation.
The following are the factors which can minimise the polarization:
1) If the electrolyte is constantly stirred the concentration change in vicinity of electrode can be avoided and if there is no increase in the concentration in the vicinity of electrode and polarisation does not take place.
2) Electrodes can be brushed off to remove the deposited gases like H2 and O2 so they don’t form the gas electrode therefore avoiding polarization.
3) The deposition of the gases on the surface of electrodes is minimised by applying black platinic chloride PtCl4 on the surface of Pt electrodes and the electrodes are known as platinised Pt electrodes.
4) Polarisation phenomenon can be eliminated by adding strong oxidising agent for e.g HNO3, chromic acid, MnO2 etc. so that as soon as H2 is formed it must be oxidised to water. Such substances which minimize the polarisation are known as depolariser.
I went through numerous books and online lecture to understand the concept of polarization, decomposition potential but couldn't get my doubt clear until I saw your videos on the same topics.all I mean to say is that the way you have put things makes the understanding so easy.thank you so much and keep making such videos 🙏
I am glad that my video helped you understand the concept.
Nice video as short and simple
Amazing video thank you
good
Greatest explanation over the network
Really spr explanation thankyou sir😊
Welcome
hello, is it important to know if the fuell cell is in prePolarization, or in postpolarization state, and what are the benefits from knowin that
thanks
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