Electrode potential - 電ｷｮｸﾃｲ

When an electrode (electronic conductor such as metal, alloy, graphite, or semiconductor) is in contact with an electrolyte solution or molten salt (ionic conductor), the internal potential of the electrode phase relative to the solution phase is called the electrode potential of that electrode. However, since the electrode potential defined in this way is the difference in internal potential between two phases with different chemical compositions, it is impossible in principle to measure its value directly. In practice, a relative value is used, which is obtained by combining the electrode system with a certain reference electrode to create a galvanic cell and measuring the terminal voltage. A standard hydrogen electrode is used as the reference electrode, but due to its structure, the hydrogen electrode is not necessarily easy to use. In practice, other reference electrodes, such as a calomel electrode or a silver-silver chloride electrode, are often used. [See alternative terms] Liquid junction potential difference, liquid junction

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

電極(金属，合金，グラファイト，半導体などの電子伝導体)と電解質溶液あるいは融解塩(イオン伝導体)とが接している場合，電極相が溶液相に対してもつ内部電位をその電極の電極電位という．しかし，このように定義された電極電位は化学的組成の異なる2相間の内部電位の差であるので，その値を直接実測することは原理的に不可能である．実際には，その電極系とある一定の照合電極とを組み合わせて一つのガルバニ電池をつくり，その端子電圧を測定することにより得られる相対的な値が用いられる．照合電極としては標準水素電極を用いるが，水素電極はその構造上，必ずしも使いやすい電極ではない．実際にはほかの照合電極，たとえば甘コウ電極や銀-塩化銀電極がよく用いられる．[別用語参照]液間電位差，液絡

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