Copper coulometer
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The copper coulometer is a one of the common application of the copper-copper(II) sulfate electrode. Such a coulometer consists of two identical copper electrodes immersed into the slightly acidic pH-buffered solution of the copper(II) sulfate. Passing of the current through the element leads to the anodic dissolution of the metal on anode and simultaneous deposition of the copper-ions on the cathode. These reactions have 100% efficiency over a wide range of the current densities. Amount of the quantity of electricity passed through the cell can be easily calculated by mass changes of any of the electrodes:
,
where Q is the quantity of electricity (coulombs); 
is the mass transported (gm); 63.546 is the atomic weight of copper, the factor 2 is due to the transport of divalent ions, and F is the Faraday constant (96485.3383).
