Silver is not a noble metal. It is transitional. Garnet
On Thu, 2004-04-15 at 10:36, Marshall Dudley wrote: > Pavel Hochmut wrote: > > > As to the content of the stomach: I apologize, that sulphuric acid in the > > stomach was maybe some trash. I shall see what happenes in the stomach > > exactly. > > But: I still consider the silver to be pretty reactive: > > 1. When you leave it on the air, it turns black within some days. It´s the > > matter of the hydrogen sulphide content in the air and silver sulphide > > appears on the silver surfaces. > > That is true, the one thing that silver reacts with quite easily is hydrogen > sulfide. This is well known and is what produces silver tarnish. > > > > > This, maybe is also answer to that, why sometimes the electrodes turn dark > > during the batch process. > > That is a reaction between hydrogen and oxygen ions and silver, hydrogen and > oxygen ions are extremely reactive. > > > I suppose, that dissolved gasses in the DW can > > react with the electrode surface. > > There is only one dissolved gas that I know of that will react with silver, > and > that is hydrogen sulfide. > > > > > As I was informed, the best way to get out the gasses from the DW is to boil > > it shortly before starting the batch. > > Can I ask somebody who faces this problem with the electrodes colour change > > to try this if it works ?????????????? > > Water is made up of 100% gases, two parts hydrogen and one part oxygen. During > electrolysis they are split up, and one goes to the anode and the other to the > cathode. Both are extremely reactive, and can produce silver compounds. The > oxygen ions will likely produce silver peroxide, which is black, and the > hydrogen ions will likely produce silver hydroxide, which spontaneously > reduces > to silver oxide, which is more of a brown color. > > > > > 2. Ocassionaly I work with plated silver material and if even I touch it > > with my hand, an exact fingerprint turns dark in several minutes on the > > silver surface. > > Silver is reactive with sulfur. The organic sulfur compounds on your finger > are > tarnishing the silver. This is the one of the few elements that silver has a > real attraction for. > > > So, I must handle it wearing gloves. There are some > > chemicals in the sweat, that silver reacts with almost instantly. It seems, > > as if it is developed photographic image of my fingerprints. > > 3. As to the reactions with the acids, as below: It is true, there is no > > reaction with the hydrochloric acid. > > If you pour sulphuric acid over silver plate, there is but a slight > > reaction, where the silver sulphate appears covering the whole surface and > > as it is not soluble, it makes passivating (= insulating) layer over the > > silver. Thus the more reaction is suppressed, the silver surface is > > "passivated". In case of CS might the situation be quite different... > > Silver is more electronegative than hydrogen, so although silver likes sulfur, > the hydrogen in the acid likes it more. No reaction should be expected, but > silver will dissolve in concentrated sulfuric acid. > > > > > As to the fuming nitric, the silver dissolves absolutely in violent > > reaction, with the sulphur nitrate resulting from this reaction. > > Try it with colloidal silver. I have, and found that the silver is untouched > by > the nitric acid as evidenced by an unchanged tyndall. If it did react then it > would produce silver nitrate, not sulfur nitrate. > > If you try it with a piece of silver, you have to use pure silver. Nitric > acid > can attack silver alloys such as 14 carat silver violently. The other metals > set > up a battery type of reaction, where the silver pulled out of the alloy by the > current as silver ions as the acid reacts with the copper, and silver ions > will > react with the nitric acid. Even .999 silver will do this slowly, so at least > .9999 should be used to do this test. > > Silver will dissolve in concentrated nitric acid, but that is different than > reacting with it. > > > > > I have asked for the above information my friend - he´s chemist. > > So the answer to the Peter´ s question is: It was fuming nitric what > > violated your silver chain. > > Once again I doubt you had a silver chain, I don't even think they make them. > Silver is way too soft to make a chain that will not fall apart. Most likely > it > was 14 carat silver, which WILL react with acids as per the above information. > However, if the acid is a strong nitric or sulfuric, then pure silver can > dissolve in it. > > See: > > http://www.madsci.org/posts/archives/mar98/889541118.Ch.r.html > > Copper and silver are fairly unreactive metals, that do not react with > ordinary acids, and do not readily react with oxygen. Both metals retain a > fairly high polish, with no tarnishing, in many environments. But keep them > out of the kitchen! Both copper and silver tarnish very readily in the > presence of sulfur, or certain sulfur compounds. In the presence of rotten > egg gas (hydrogen sulfide), or certain organic sulfur compounds, or even > yellow elemental sulfur, copper and silver surfaces readily react to form > black layers of copper or silver sulfide. These layers are very hard and > insoluble; they are also rather unsightly! Cooking eggs is a notorious > source of sulfur compounds that tarnish silver; so are natural gas or town > gas fires. > > According to http://www.webelements.com/webelements/elements/text/Ag/chem.html > > Silver dissolves in sulfuric and nitric acids, but does not react with them. > > Silver and gold are called noble metals because of their inert nature. > > The reactivity of metals is in the following order: > > potassium > sodium > calcium > magnesium > aluminum > zinc > iron > lead > copper > mercury > silver > platinum > gold > > As you can see, only platinum and gold are less reactive than silver. > > http://homepages.westminster.org.uk/nick.hinze/Notes/Lower%20Shell/metals.htm > > One general idea is that the more reactive a metal, the greater its tendency > to > react and form compounds. This is why metals above copper in reactivity are > rarely found native, whereas gold and silver are often found in their natural, > uncombined state. > > Some unreactive metals, like gold, silver and copper can be found uncombined > in > the earth. However most metals are found > combined with other elements in compounds known as minerals (e.g. metal oxides > and sulfides). Rocks containing these > minerals are called ores. Ores are the raw materials for making metals. > > Extremely unreactive metals such as silver, gold and platinum are often found > native (uncombined) in underground deposits. No > chemical method of extraction is therefore required in such cases. > > > Also see: > > http://www.learn.co.uk/default.asp?WCI=Unit&WCU=35698 > > http://www.sciencenet.org.uk/database/chem/industrial/c00109b.html > > http://www.wolds-silver.freeuk.com/silver_properties.htm > > Chemically, silver metal is not very active. It is insoluble in dilute acids > and > alkalis, but it > does dissolve in concentrated nitric or sulfuric acid. It does not react to > any > great extent > with oxygen or water at ordinary temperatures. However, sulfur and sulfides > readily attack > silver, to cause tarnishing through the formation of a surface layer of water > insoluble black > silver sulfide (Ag2S) . This explains why eggs, which contain sulfur (in the > proteins), are > efficient tarnishes of silver. Tarnishing is also slowly produced by the small > amounts of > hydrogen sulfide (H2S) present in the atmosphere. > > So although silver will dissolve in concentrated nitric or sulfuric acids, it > does not react with them. This tends to support all my experiments where I was > trying to react silver with something so I could test for it at room > temperature > and was unsuccessful. The only thing I was able to get to work was mixing > with a > fuming acid, and boiling dry. Apparently it dissolves in the acid, then when > boiling dry the hydrogen is driven off leaving the nitrate or sulfate radical > behind, and it will then react with the silver since the hydrogen is now not > available to compete with it. > > Marshall > > > > > Pavel H. > > > > Marshall Wrote > > > > silver is one of the most inert metals there is, it is slightly more > > reactive than gold, but > > not much. You can drop it into fuming nitric, sulfuric and hydrochloric > > acids > > (independently) and nothing happens. > > > > Marshal: > > > > As a child once I try to clean a silver chain in an Ounce of the acid > > tinners use to solder. The chain completely dissolved after a few minutes. > > > > What kind of acid do You think it was? > > > > Peter R > > > > -- > > The Silver List is a moderated forum for discussing Colloidal Silver. > > > > Instructions for unsubscribing are posted at: http://silverlist.org > > > > To post, address your message to: [email protected] > > Silver List archive: http://escribe.com/health/thesilverlist/index.html > > > > Address Off-Topic messages to: [email protected] > > OT Archive: http://escribe.com/health/silverofftopiclist/index.html > > > > List maintainer: Mike Devour <[email protected]> >
