Salt Bridge





Some of the importance of Salt bridge are listed below:

(1). In Daniell cell electrons are released by anode and accepted by cathode. Therefore Zn changes into Zn^{++} ion and Cu^{++} changes into Cu. During this change there will be accumulation of charge near the two electrodes which prevents further flow of current. Due to this the electrochemical changes stop and current drops to zero.

To prevent this, salt bridge is placed in between the two electrodes, In the presence of salt bridge, the charges flow towards the oppositely charged electrode. The anions move from the Cu-electrode and through the CuSO_4 solution, salt bridge and ZnSO_4 solution to the Zn rod. The cations move in the reverse direction as Zn rod to Cu rod. Thus flow of current is maintained when salt bridge is used in the Daniell or Galvanic cell.

(2) It connects the solutions of two half cells to complete circuit.

(3) It avoids any transference of the solutions of two half cells.

(4) It minimizes or prevents liquid junction potential. (It is potential difference which develops between the two solutions in contact with each other.)

  • If salt bridge is removed the potential of cell drops to zero.
  • In case of KNO_3, KCI etc. The mobility of cations and anions is the same.


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