In a message dated 4/4/01 7:26:59 AM EST, [email protected] writes: << Subj: Re: CS>Model to Explain Charge Buildup for LVDC CS Electrochemical Reactions Date: 4/4/01 7:26:59 AM EST From: [email protected] (Ivan Anderson) Reply-to: [email protected] To: [email protected] ----- Original Message ----- From: <[email protected]> > Ivan: To keep things as simple as possible, the following discussion pertains > to the initial few minutes of CS electrolysis. It seems to me that if salt is > added to water, the ionic species responsible for carry the charge changes > from silver ions (in the case when no salt is present) to Na+ and Cl- which > then carry all of the charge between the two silver electrodes. If NaCl is > carrying ~100% of the charge, how can a charge buildup occur for Ag+ ions > when they no longer play a significant charge carrying role? Roger as the Na+ and Cl- are present as separate ions, and all the reactions take place at the electrode solvent interface, the oxidation of Ag ----> Ag+ (0.8V) will procede before the oxidation of Cl- ----> Cl (1.4V).
Ivan: Cl- can STILL carry the charge without undergoing a reduction to chlorine gas. At the electrode surface, the half cell reaction requiring the lowest EMF will proceed which, generally speaking, will NOT be the reduction of chloride to chlorine gas.. > In the former case (no salt is present), Ag+ cations are just beginning to be > produced at the anode so there is very little Ag+ available to transfer > charge to the cathode, AND other than OH- (at ~10^-7 moles/liter), there are > no significant amounts of other anionic species available to carry the charge > from the cathode to the anode. Consequently, a charge buildup occurs similar > to what happens in a with the "no salt bridge" Zn/H2 battery. When salt is > added to the water, a charge buildup cannot occur because Na+ and Cl- are > available to carry charge between the cathode and anode respectively. But for every Ag+ ion that enters solution some other species is gaining an electron and charge neutrality is preserved. Ivan: No doubt you are correct. How about, 2H2O + 2e --------> H2(g) + 2OH- E = 0.81 as mentioned previously? However, at least during the early part of the CS electrolysis, there may be an excess of positive ions (Ag+) near the anode, and an excess of negative ions(OH-) near the cathode, similar to the two beaker charge buildup in the Zn/H2 example I used previously. However what happens when Ag+ ions are added from an outside source, such as plasma arc, the net charge must increase then? Ivan: I think we are talking about an entirely different mechanism, one that does not involve half cell reactions. If SOME silver ions are produced in the plasma (and an earlier literature search I did indicated that there is too little energy generated from our HVAC power supplies to produce silver ions in the gas. Rather the plasma contains mostly gaseous silver that condenses in the water as neutral CS particles.) then the following reaction is possible, (1) [Ag+] + H2O ------> AgOH(s) + [H+] Perhaps reaction(1) explains the frequent the low pH associated with the production of HVAC CS by the arc method. Roger -- 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]>
