Salt Bridge - Enkyo

A type of liquid junction used to connect two electrode system solutions when measuring electrode potential differences or in battery experiments. Typically, an inverted U-shaped or H-shaped glass tube filled with a salt solution is used, and the tube is plugged with a wooden core or cotton at both ends to prevent the electrode system solutions from mixing, or the inside of the salt bridge is solidified with agar or gelatin. To reduce the liquid junction potential difference and the increase in circuit resistance due to the salt bridge, a concentrated solution of a salt in which the mobilities of both anion and cation ions are as equal as possible is used as the salt solution. A concentrated solution of potassium chloride is generally used, but in cases where potassium chloride reacts when it comes into contact with the electrode system solution, ammonium nitrate or potassium nitrate can be used instead.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

電極電位差の測定や電池の実験などにおいて，二つの電極系の溶液を接続するために用いられる液絡の一種．通常，ガラス管を逆U字状あるいはH字状にしたものに塩類溶液を満たしたものを用い，電極系の液が混合しないように管の両端に木芯または綿の栓をしたり，塩橋内を寒天やゼラチンで固めたりして接続する．液間電位差を小さくし，かつ塩橋による回路抵抗の増加を小さくするため，陰陽両イオンの移動度がなるべく等しい塩の濃厚溶液が塩類溶液として用いられる．一般に塩化カリウムの濃厚溶液が用いられるが，塩化カリウムが電極系の溶液と接触して反応する場合には，硝酸アンモニウムや硝酸カリウムを代用する．

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