The function and working principle of salt bridge in primary battery is that salt bridge plays the role of making the whole device form a channel.

The function of external salt bridge solution:

1. Prevent the salt bridge solution inside the reference electrode from leaking into the test solution from the liquid joint to interfere with the determination?

2. Prevent harmful ions in the test solution from diffusing into the internal salt bridge solution of the reference electrode and affecting its electrode potential.

Preparation method of solid U-shaped salt bridge;

3g agar+100ml saturated potassium chloride solution, heated in water bath to make solution, sucked into a u-shaped glass tube with a suction ball while it was hot, cooled and frozen.

Main components of salt bridge of primary battery: KCl agar, or agar of other salts.