Salt Bridge and its Significance
(i) Salt bridge is U – shaped glass tube filled with a gelly like substance, agar – agar (plant gel) mixed with an electrolyte like KCl, KNO3, NH4NO3 etc.
(ii) The electrolytes of the two half-cells should be inert and should not react chemically with each other.
(iii) The cation as well as anion of the electrolyte should have same ionic mobility and almost same transport number, viz. etc.
(iv) The following are the functions of the salt bridge,
(a) It connects the solutions of two half - cells and completes the cell circuit.
(b) It prevent transference or diffusion of the solutions from one half cell to the other.
(c) It keeps the solution of two half - cells electrically neutral.
(d) It prevents liquid – liquid junction potential i.e. the potential difference which arises between two solutions when they contact with each other.