Class 12 Chemistry Electrochemistry Salt Bridge

Salt Bridge

  • Salt bridge is an inverted U-tube like structure.
  • The tube is filled with concentrated solution of an inert electrolyte.
  • The electrolyte does not undergo any sort of chemical reaction nor does it reacts with concentrated solution in the two half cells.
  • Most of the time salts like KCl, KNO3, NH4NO3 are used as electrolyte.
  • Salt bridge is constructed by filing the U-tube with a mixture prepared by mixing agar-agar or gelatin with a hot concentrated solution of the electrolyte.
  • The apparatus is then cooled and consequently the solution fixes within the U-tube in the form of gel.
  • This prevents the intermixing of fluids.
  • The either ends of the tube are then sealed using cotton wool in order to reduce diffusion.
  • The main advantage of suing this bridge is that it prevents the arousal of potential difference (also called liquid junction potential) when two solutions are in contact with each other.
  • It completes the electrical circuit as it connects the electrolytes in the two half cells.
  • It avoids the chances of diffusion of solutions between the half cells.
  • It maintains electrical neutrality by providing a path for the movement of ions.

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