Sam, James is correct...and psychic.
Oxidation is the removal of electrons. Reduction is the gaining of electrons. A redox reaction is a two way street (most interactions of matter involve redox reactions)... that which is oxidised looses an electron, that which does the oxidising is reduced and gains that electron. The apparent contradiction in terms comes about because at the time when these reactions were described the electron was not known. What was described was the gain and loss of the positive charge. Hence reduction is the gaining of a negatively charged electron... and the REDUCTION of positive charge. The term oxidation comes about because the reaction it describes was first observed with oxygen. There are four or five oxides of silver, but all are unstable... the most stable being Ag2O which decomposes upon mild heating. Ag+ is actually quite a strong oxidising agent. James writes: > These processes take place with electrons of the atoms outer shells. The > charges present are called the valence of the atom or ion. It is not > clear to myself how the positive charge on a cluster of silver atoms > originates, but I don't think it is the valence charge of a single Ag atom > which is a part of the cluster. I'm not sure why you have trouble with this. Do you believe that electrons are stripped from silver atoms at the anode? As noted above a 'positive' charge is really a less negative charge, its origin being that a silver particle that has lost one or more electrons is less negative than one that has all its electrons, and is therefore 'positively' charged. The physical chemistry of the transition metals (silver is one) is not fully understood, but it seems they can loose electrons from inner shells and exist with 'positive holes' in their electron cloud, and this is thought to be the reason for the unusual properties of these elements. The fact is that groups of ions do exist together as clusters and in deed particles of the same type with similar charges can be drawn together. Regarding H+. It is thought that the electron deficiency is passed from water molecule to water molecule, explaining why experimental results for the mobility of H+ ions far exceeds its possible motion. There is no reason that I know of to believe it becomes trapped as a static H3O- complex ion, if the silver atoms have no charge, why would they be involved in a micelle of water molecules in the first place. Would it hook up with some oxidising (reducing?) hussy? Only if they bumped in the night with the right attitude. Sure, if that joker can choke back the laughter and give us the low down of metallic sol chemistry he can have your eternal gratitude and my mickey mouse watch. 'Chaos reigns...my work here is done.' Ivan. ----- Original Message ----- From: James Osbourne, Holmes <[email protected]> To: <[email protected]> Sent: Wednesday, 27 October 1999 12:32 Subject: RE: CS>Colloid? was baking soda > Yes, Sam, there is an argument with that, > > and, I predict you will hear from Ivan shortly... > > Oxidation and reduction always occur together. An electron > donator---almost always a metal---is called a reducing agent and is said to > be oxidized when it donates the -e. The electron receptor is called the > oxidizing agent, and in the process is said to be reduced. The process is > reversible under some conditions. I think there is some historical > connection with oxygen, which is certainly an oxidizing agent. What you > are describing is the creation of silver oxide, not a charged colloidal > particle. > > These processes take place with electrons of the atoms outer shells. The > charges present are called the valence of the atom or ion. It is not > clear to myself how the positive charge on a cluster of silver atoms > originates, but I don't think it is the valence charge of a single Ag atom > which is a part of the cluster. > > There is no such thing as a free proton in an aqueous solution, as a > hydrogen atom missing its electron; a nude proton bobbing around with its > plus hanging out. Instead, the h+ gets involved with a water molecule to > become H30+. > > Now, pure speculation: Or, is it possible that it gets 'associated' with a > cluster of Ag? Trapped inside a micelle with a bunch of negative ends of > some water structure? Data, are you there..., talk to me... > > If it were a missing electron, would not the Ag atom hitch up with some > passing oxidizing agent hussy? > > This issue, the cause of the charge, is the source of much discussion, and > even some small amount of contention on this list. > > There must be someone lurking out there who is who knows, and is sitting > back yucking as we founder about with these rube questions. > > Where is Robert Hunter when we need him the most.... > > James Osbourne Holmes > [email protected] > > > -----Original Message----- > From: Sam Earle [SMTP:[email protected]] > Sent: Tuesday, October 26, 1999 1:53 PM > To: [email protected] > Subject: Re: CS>Colloid? was baking soda > > >Positively charged silver particles are already oxidised (lost an > >electron). > > I've seen this said several times, and at the risk of having my ears boxed > by the real scientists on the list, I have to say it looks like nonsense. > The loss of an electron gives a positive charge. That's not oxidation. > Oxidation is picking up an oxygen atom and thus becoming part of a > compound -- an oxide. > > Any argument with that? > > Sam > > > > -- > 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] > > List maintainer: Mike Devour <[email protected]> >
