1. May I ask, if the AgAgCl electrode is encapsulated in a KCl solution with low concentration, something like 10mM or 50 mM, can it still be used as reference? why?
2. If the AgAgCl electrode is encapsulated in a solution not only have KCl, but also other ions, like KNO3, CaCl, Na2HPO4, what will happen if I use it as reference electrode?
@ Yu, your first question answer is no. Because reference electrode is an electrode which has a stable and well-known electrode potential. The high stability of the electrode potential is usually reached by employing a redox system with buffered or saturated concentrations of each participant of the redox reaction. Therefore, you need saturated concentration of potassium chloride solution (36 % w/w).
Regarding 2nd question you can not use it as reference electrode as reference electrode should maintain the neutrality in the system by providing enough negative ions equal to the positive ions during oxidation.
Hi, Yu Chen,
1. You can use any concentration of the chloride salt in the internal electrolyte of the Ag/AgCl reference electrode whose potential is a function of the chloride ion concentration according to the Nernst equation. The commonly used salt is KCl because the transference numbers of the K+ and Cl- ions are almost equal, minimising the possible liquid junction potential (LJP) across the membrane. However, if for any reason you are unable to use KCl in the internal electrolyte, you can use another chloride salt, which can surely lead to LJP, but the influence of the LJP is usually minimal as long as the LJP remains constant or changes insignificantly.
2. It will depend on your application. If you wish to establish some analytic understanding with reference to the Ag/AgCl electrode potential in place of the standard hydrogen electrode potential, you cannot introduce other salts into the internal electrolyte. However, if you just wish to use the reference electrode to control the potential of a working electrode, you can add almost any salt in the internal electrolyte as long as the added salt is soluble and does not react with or dissolve the AgCl coating on the Ag wire. In such cases, the potential of the Ag/AgCl electrode will differ from what is expected of a standard Ag/AgCl electrode, but it can be experimentally determined by, for example, using another standard Ag/AgCl electrode or the SCE.
Using this refrence electrode with bridge as KNO3 so AgCl precipitation is stoped
Dear colleagues,
Dr. George Zheng Chen is absolutely right. Concentration of the chloride salt in a filling solution of the Ag/AgCl reference electrode may be any, with the potential being directly related to the logarithm of chloride ion activity. The use of saturated KCl (also saturated with AgCl to prevent formation of soluble complexes of Ag) is explained simply by the fact that chloride concentration (activity) remains constant when the solution is evaporated.
Use another référence électrode as sulfate mercure électrode is praticable without ans problem
A reference electrode is used because you want to be certain that a certain metal has a constant (not variable) potential with respect to the solution. The constant potential would be the result of electrochemical equilibrium between a redox couple at the metal's surface. AgCl + electron Ag + Cl-(solvated)
A distortion of the electrode potential will be 'buffered' by the Ag and the AgCl in the solid-state on the electrode. So any chloride concentration will do for buffering action as a reference electrode. The value of the reference electrode potential will however depend on the chloride concentration. Presence of additional ions will make little difference, as long as they do not form insoluble precipitates (comparable to AgCl) or complexation reactions. Small amount of sulphide reacts strongly with silver and mercury. It is always good practice to play around with your reference electrodes, have a couple at your disposal. Just test your electrode system until you are comfortable with it.
If your electrodes are connected to electronics, it may also make sense to check for 50/60 Hz hum by a scope.
George Zheng Chen Anthonie Wilhelmus Muller Rouvim Kadis What is Ag/AgCl is kept without electrolyte for long time, will its performance be affected?
Dear Yu Chen . See the following useful RG link: Article Microfabricated Reference Electrodes and Their Biosensing Applications
Kindly see also the following useful RG links: Article Versatile 3D‐Printed Micro‐Reference Electrodes for Aqueous ...
https://eprints.soton.ac.uk/415913/1/Reference_electrodes_review_paper_with_Revisions.pdf
Also check please the following useful RG links: Article A flexible Ag/AgCl micro reference electrode based on a pary...
https://www.gamry.com/support/technical-support/frequently-asked-questions/reference-electrode-care-overview/
https://research.utwente.nl/files/100616781/1_s2.0_092540059080243S_main.pdf
The following RG link is also very useful: Article Screen-printed reference electrodes for potentiometric measurements
Reference electrodes maintain constant potential by the vertue of its composition. For the Silver-silver cloride reference electrode or the calomel reference electrode the potential is constant because it contains a fixed chloride concentration.Sep 29, 2017
https://www.researchgate.net › post
How do reference electrode maitain their potentials? - ResearchGate
Ag/AgCl is a second type electrode in which the metal is in contact wit its low soluble salt and the anion of that salt. In your case, the metal is Ag in contact with its low soluble salt AgCl + its anion Cl(-) and the reaction is AgCl + e = Ag + Cl(-). This reaction is the half cell of Ag/AgCl ref. electrode.Jan 19, 2015
https://www.researchgate.net › post
What are the reactions going on in Ag/AgCl reference electrode?
https://ceocor.lu/download/Reference-Electrodes-for-Monitoring-of-Cathodic-Protection-on-Buried-Pipelines-R11-Approved-November-2018.pdf,this link may be helpful.
Ag/AgCl electrode kept without electrolyte solution. An answer to the question.
A new Ag/AgCl electrode can be stored without electrolyte solution. Indeed, some manufacturers supply their electrodes in a "dry condition" so that the user may fill them with the solution himself. This allows the user to choose the appropriate filling solution.
Quite another matter is the drying of the electrolyte solution inside the electrode. Crystallization or precipitation of the KCl solution in the pores of a fritted disc or within any other restrained liquid junction can cause malfunctions of the electrode. Increased response time and appreciable stirring shift are common evidences of poor liquid junction performance. For this reason, frit should never be allowed to dry out. If it happened anyway, do not be sad - soaking in water for a long time can return the electrode to its normal state in many cases.
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