View source for Copper–copper(II) sulfate electrode

{{Use dmy dates|date=February 2025}}
[[File:CopperSulphateElectrode.png|thumb|upright=1.3|Diagram of an electrode used in the field]]
The '''copper–copper(II) sulfate electrode''' is a [[reference electrode]] of the first kind,<ref>Protopopoff, et al, p. 15</ref> based on the [[redox]] reaction with participation of the metal ([[copper]]) and its salt, [[copper(II) sulfate]].
It is used for measuring [[electrode potential]] and is the most commonly used reference electrode for testing [[cathodic protection]] [[corrosion]] control systems.<ref>Peabody p. 3</ref> The corresponding equation can be presented as follow:
:Cu<sup>2+</sup> + 2e<sup>−</sup> &rarr; Cu<sup>0</sup>(metal)

This reaction is characterized by reversible and fast electrode kinetics,<ref>Protopopoff, et al, p. 13</ref> meaning that a sufficiently high current can be passed through the electrode with 100% efficiency of the redox reaction ([[solvation|dissolution]] of the metal or cathodic [[Deposition (chemistry)|deposition]] of the copper-ions).

The [[Nernst equation]] below shows the dependence of the potential of the copper-copper(II) sulfate electrode on the [[activity (chemistry)|activity]] or [[concentration]] copper-ions:

:<math>
E=0.337 + \frac{RT}{2F} \ln a_{\rm Cu^{2+}}
</math><ref>Protopopoff, et al, p. 15, Eq 2</ref>
The potential of a copper–copper sulfate electrode is +0.314 [[volt]] with respect to the [[standard hydrogen electrode]].{{citation needed|date=February 2012}} 

== Design ==
Commercial reference electrodes consist of a plastic tube holding the copper rod and saturated solution of copper sulfate. A porous plug on one end allows contact with the copper sulfate [[electrolyte]]. The copper rod protrudes out of the tube. The negative lead of a [[voltmeter]] is connected to the copper rod.

== Applications ==
A copper–copper(II) sulfate electrode is used as one of the [[half cell]]s in the galvanic [[Daniell cell|Daniel-Jakobi cell]]. 

Copper-copper(II) sulfate electrodes are used in the [[Copper coulometer]]. It contains two identical copper electrodes immersed in a slightly acidic [[Buffer solution|pH-buffered]] solution of [[copper(II) sulfate]].

==Notes==
{{Reflist}}

==References==
* E. Protopopoff and P. Marcus, Potential Measurements with Reference Electrodes, Corrosion: Fundamentals, Testing, and Protection, Vol 13A, ASM Handbook, ASM International, 2003, pp.&nbsp;13–16
* A.W. Peabody, Peabody's Control of Pipeline Corrosion, 2nd Ed., 2001, NACE International. {{ISBN|1-57590-092-0}}

{{DEFAULTSORT:Copper-copper(II) sulfate electrode}}
[[Category:Electrodes]]
[[Category:Corrosion prevention]]


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