what is salt bridge

A salt bridge is a laboratory device used in electrochemistry to connect the oxidation and reduction half-cells of a galvanic cell, maintaining electrical neutrality within the internal circuit. It prevents the accumulation of positive and negative charges around the respective electrodes, allowing a smooth reaction to take place and the continual flow of electrons. The salt bridge usually consists of a strong electrolyte made up of ions, such as AgNO3 or KCl. It can be a U-shaped glass tube filled with a relatively inert electrolyte or a combination of potassium or ammonium cations and chloride or nitrate anions, which have similar mobility in solution. The purpose of the salt bridge is to act as a source of spectator ions that can migrate into each of the half cells to preserve neutrality, reducing the junction potential between the solution interface of the two half cells/Analytical_Sciences_Digital_Library/In_Class_Activities/Electrochemical_Methods_of_Analysis/02_Text/5._Electrochemical_Cells). In addition to its use in electrochemistry, the term "salt bridge" is also used in the context of protein and supramolecular chemistry to describe a combination of two non-covalent interactions: hydrogen bonding and ionic bonding).