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The Clark electrode is an electrode that allows amper metric measurement of dissolved oxygen activity. The electrode has glass body with a 5-mm opening at the base. Inside this opening is a 10 to 10 to 40 - mm long plug of silicone rubber, which is permeable to $O_2$. Oxygen diffuses into the electrode through the rubber and is reduced at the Au tip on the Pt wire, held at -0.75V with respect to the $Ag\left|AgC\right|$reference electrode. A Clark electrode is calibrated by placing it in solutions of known$O_2$concentration, and a graph of current versus $\left[O{O}_2\right]$.

• By reducing oxygen to water on platinum electrode at -0.75V voltage of with respect to silver-silver chloride.
• Silicone rubber of size$10\mathrm{μ³¾}\mathrm{to}40\mathrm{μ³¾}$to permeable to oxygen is filled on body of platinum electrode.
• The concentration of oxygen is proportional to current. The electrode in known oxygen concentration should be calibrated.