Frank, I am a bit confused.
I do not see why anions are required at all for silver ions to go into solution. The ions will be solvated, surrounded by water molecules. If there are no anions, there will be nothing for the silver to complex with and so the saturation point will depend upon the interaction between the ions themselves. There is 10^-7mol/L OH- ions in water at pH 7, which will allow Ag+ ions to reach a concentration of 0.15mol/L which is about 16.2g/L or 16.2ppt, given that the solubility constant of AgOH is 1.5 x 10^-8 The solubility constant of Ag2Co3 is 6.2 x 10^-12 which gives a concentration of 2.32 x 10^-4 mol/L of Ag+ which is about 25mg/L. In any event CO2 will dissolve in water to a concentration of about 10^-5M and result in a pH of 6.3 . However the CO2 exists primarily as a hydrated species, of which about 0.1% reacts to form H2CO3. This gives us about 10^-8M of CO3, which gives about 2.4 x 10^-2M of Ag+ (2.5g/L). So it is not the concentration of the anions which limit the solubility of silver at far greater than normal CS levels. How do you explain the 13.3ppm limit? Thanks Ivan. ----- Original Message ----- From: "Frank Key" <[email protected]> To: <[email protected]> Sent: Sunday, 25 March 2001 04:03 Subject: Re: CS>Re: saturated solution > Ivan wrote: > > > Roger asked about anions formed at the cathode. As long as there are > > anions (OH-) formed at the cathode silver ions can enter the solution at > > the anode. The presence of carbonate is not required. > > > > However, if silver ions are introduced by some method other than > > electrolysis only then would your words be correct, as far as I can see. > > If carbonates are not present, then silver ions will saturate pure water. When the water cools to room temperature, the solution becomes supersaturated and the silver ions are forced out of solution as large metal flakes. > > If at room temperature the ionic silver is greater than 13.3 ppm, then the only explanation is that carbonates are providing the anion for the additional silver cations. > > frank key --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.237 / Virus Database: 115 - Release Date: 07/03/2001 -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
