Is it necessary to have the Ag wire dipped into a KCl solution during using it as a reference electrode? Or can I just use the Ag wire having a layer of Chloride on it?
I would not recommend what you suggested. You can easily form a thin chloride layer by dipping a silver wire in a KCl solution and use this as an anode in a short electrolysis step. You will see the AgCl layer by the color change to brownish. Alternatively you can drop some AgCl precipitate into the KCl solution and use a blank silver wire. The chloride concentration will determine in both cases the Galvani potential at this reference half-cell.
Absolutely. The potential is determined by the chloride concentration. It can be used if your buffer/sample/mobile phase has certain known constant chloride concentration, but it must not contain anions that would poison the Ag, such as sulfide, phosphate, etc.
However, be careful if using a biological buffer like Tris, because it reacts and then this reference electrode isn't at a stable potential.
As a followup to Shelley's comment, Tris only causes a problem when one is using a commercial reference electrode, either single or combination, when the liquid junction is made using a linen fiber junction (Are they used anymore?) or if silver ions contact the Tris buffer in which case complexation can occur.
Take a piece of Silver wire, dip it in a 1 M HCl solution, saturated with NaCl and wire it to an 9V battery. Use a stainless steel wire as a anode. Connect the Ag wire to the cathode and the stainless steel wire to the anode of the battery to promote the electrolysis mentii«oned by the coleagues. If they are well connected, you will see bubbles from the stainless steel wire (from the electrolyisis), otherwise the solution will become yelowish. If you use working microelectrodes, use a silver wire with significantly larger diameter and lenght. It will make the drift in potential neglectable. Good luck!
Unless I misunderstood what you are suggesting, I believe that you have your polarities reversed. The silver wire should be the anode to produce silver ions which then, in combination with the chloride ions in solution, form silver chloride on the silver wire surface. I'm not sure that HCl is really necessary since 9V should be more than enough to electrolyze the solution.
You are right, they should be reversed indeed. About the HCl, i always used it and it worked, even in in vivo applications where biofouling is a major issue.
Hi, is there any gel-like thing that I could use instead of KCl solution during using (not fabricating) the Ag/AgCl reference electrode? thanks.
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