rexresearch.comTSTO
PREPARATION & PROPERTIES
TetraSilver
TetrOxide ( TSTO )
Inorganic Syntheses IV: 12 (Chapter 1B, #
3)
Silver (II) Oxide
by
Robert Hammer & Jacob Kleiberg
Silver (II) Oxide
by
Robert Hammer & Jacob Kleiberg
Silver (II) oxide has been made by the hydrolytic action of boiling water on a substance of the approximate formula Ag7O8NO3, a material which obtained by the electrolytic oxidation of silver (I) nitrate solutions (Ref. 1-4). A more rapid and convenient process for the preparation of this oxide involves the oxidation of silver (I) nitrate by means of potassium peroxydisulfate ("Oxone") in an alkaline medium (Ref. 5, 6).
Procedure
72 grams of sodium hydroxide (NaOH, 1.8 mols) in pellet form is added portionwise, with constant stirring, to 1 liter of water, which is maintained at approximately 85°. Seventy-five (75) grams of potassium peroxydisulfate (0.28 mols) in the form of an aqueous slurry is added to the hot alkaline solution; this is followed by the addition of 51 gr of silver (I) nitrate (0.30 mol) dissolved in a minimum amount of water. The temperature of the resulting mixture is raised to 90°, and stirring is continued for approximately 15 minutes.
The precipitate of black silver (II) oxide is filtered on a large Buchner funnel, and sulfate ion is removed by washing with water which has been made slightly alkaline with sodium hydroxide. The product is air-dried.
Yield, 35 gr (94%).
Analysis: Calculated for AgO: Ag, 87.08%. Found: Ag, 86.93%, 86.90% (by gravimetric chloride method, after dissolution of the product in 3N nitric acid).
Properties
There are many indications that AgO is a true oxide, rather than a peroxide, and is, therefore, properly named silver (II) oxide. The compound does not give free hydrogen peroxide when acidified but behaves in a manner more characteristic of a compound in which the metal ion is present in a strongly oxidized valence state, which may be stabilized by coordination. In dilute acid, oxygen is immediately evolved; in concentrated acid, intensely colored solutions are formed (brown in nitric acid and olive green in sulfuric acid). These latter solutions are relatively stable, though they gradually decompose with an accompanying liberation of oxygen, and have been show to possess paramagnetism which is quantitatively consistent with the expected magnetic moment of the postulated silver (II) species (Ref. 7). In the solid state, this oxide is stable when heated to 100°, but it decomposes at higher temperatures. The solid possesses semiconductor properties and is diamagnetic. These phenomena have been explained by Neiding and Kazarnovskii (Ref. 7) on the assumption that the silver is actually trivalent in its crystal lattice with both O-Ag and Ag-Ag bonds. The difference in the specific volumes of AgO and Ag2O is less than would be expected if AgO were a peroxide (Ref 7). Equilibrium of silver (II) oxide with dilute nitric acid gives the black paramagnetic oxynitrate (Ag7O8NO3), a substance in which part of the silver is apparently in the tripositive state.
References
1. Mulder: Rec. Trav. Chim. 17: 129 (1898)
2. Watson: J. Chem. Soc. 89: 578 (1906)
3. Jirsa: Zeit. Anorg. u. Allgem. Chem. 148: 130 (1925)
4. Noyes, et al.: J. Amer. Chem. Soc. 59: 1326 (1937)
5. Barbieri: Chem. Berichte 60: 2427 (1927)
6. British Patent # 579,817; Chem. Abstr. 41: 1401h (1947)
7. Chem. Abstr. 45: 8385h (1951)
http://81.207.88.128/science/chem/exps/Ni+persulfate/index.html
PREPARATION OF TETRASILVER TETROXIDE
Oxidation of silver to its +3 oxidation state
Prepare a solution of silver nitrate or silver oxide in dilute nitric acid. Any concentration of 1 to 2 mol/l for the nitric acid is OK.
Add some solid sodium persulfate to the liquid. Adding a fairly concentrated solution of sodium persulfate also works. When this is done, then the liquid becomes brown and remains clear. The brown color is due to silver (III) ions. The brown color is formed quickly, although not instantaneously. It takes a few seconds.
Silver (III) ions are not very stable. Even in the fairly strongly acidic liquids, the compound slowly decomposes. A black precipitate is formed and oxygen is released very slowly. This black precipitate is due to combined hydrolysis and reduction of the silver (III) ions. A mixed silver (I) silver (III) oxide is formed, which precipitates from the liquid as a black solid.
Remarkably, when persulfate is added to a neutral solution of silver nitrate, then no brown color is formed. In that case the liquid first remains colorless, but in the course of a few minutes it slowly turns turbid and a dark brown/black precipitate is formed. Apparently, at higher pH, the brown silver (III) ion is not formed at all and the mixed silver (I) silver (III) oxide is formed immediately.
Addition of sodium hydroxide, quick formation of Ag(I)Ag(III)O2
When the brown liquid is added to a solution of sodium hydroxide, then the process of formation of the black silver (I) silver (III) oxide is almost immediate. As soon as the brown liquid is added to a solution of sodium hydroxide, a dark brown very finely divided precipitate is formed. The solid particles stick together quickly and larger black particles are formed. The black solid slowly evolves oxygen and every few minutes it moves to the surface, due to many small bubbles of oxygen, which are trapped inside the precipitate. When these small bubbles of oxygen are lost, then the solid mass sinks to the bottom again. This 'dance' is repeated several times.
The three pictures below show the liquid, immediately after adding it to a slight excess amount of a solution of NaOH. The second picture shows the same liquid a few minutes later, when the particles of the precipitate stick to each other. The final picture shows the precipitate near the surface, due to lots of trapped bubbles of oxygen. All the pictures clearly show the bubbles of oxygen.
Whether the brown color is due to plain Ag3+ or due to some mixed valency complex of silver (I) and silver (III) is not clear to me. It might be that the brown color is due to a mixed valency complex of silver (I) and silver (III). Examples of mixed valency complexes are also given on the following pages: copper (I) / copper (II) and titanium (III) / titanium (IV).
Reaction with silver
In acidic media, persulfate is capable of oxidizing silver (I) ions to silver (III) ions. These silver (III) ions are brown.
Ag+(aq) + S2O82-(aq) ? Ag3+(aq) + 2SO42-(aq)
Silver (III) ions are not very stable. This liquid slowly looses its color and gives off oxygen. A black precipitate is formed of silver (I) silver (III) oxide. The silver (III) ions slowly oxidize the water, in which they are dissolved.
4Ag3+ + 6H2O ? 2AgIAgIIIO2 + 12H+ + O2
When the liquid is made more basic, then the reaction proceeds much faster, as the experiment demonstrates. The following reaction occurs in that case.
4Ag3+ + 12OH– ? 2AgIAgIIIO2 + 6H2O + O2
The compound AgAgO2 in turn also decomposes. It slowly looses oxygen and is converted to simple silver (I) oxide.
2AgIAgIIIO2 ? 2AgI2O + O2
General remarks
Both the silver (III) compounds and the NiO2 compound are very strong oxidizers. Both compounds are capable of oxidizing manganese (IV) and manganese (II) to the +7 oxidation state as permanganate and chromium (III) is oxidized to the +6 oxidation state as dichromate or chromate.
Silver nitrate is a catalyst in many reactions with persulfate in acidic media. Persulfate is a strong oxidizer, but it also is somewhat sluggish. The reaction between silver (I) and persulfate in acidic media, however is quite fast. Silver (III) in turn reacts with manganese (II) or chromium (III) quickly to form permanganate or dichromate, itself being converted to silver (I) again. So, in the presence of a small amount of silver nitrate, the persulfate anion can be used as a fast and very strong oxidizer. The catalytic action of silver is based on the fact that an other pathway for the final redox reaction is provided, with Ag3+ as intermediate species.
A similar catalytic action can be observed with nickel hydroxide in basic solutions. The reaction between nickel hydroxide and persulfate is very fast (instantaneously, at least in terms of human observation). Nickel (IV) oxide in turn is capable of oxidizing e.g. manganese (IV) oxide to permanganate. This property can be used as a sensitive method for detecting manganese.
Another important remark is that in both experiments, the presence of chloride ions should be avoided. Especially with the silver experiment, chloride ions are really disturbing. They make the liquid cloudy, due to formation of silver (I) chloride and they interfere, due to oxidation to chlorine.
For the nickel experiment the presence of chloride is not of a direct concern, but if one wants to use NiO2 for detection of manganese by conversion to the deep purple permanganate, then even small amounts of chloride interfere and make the detection fail.
More info on the interesting and remarkable subject of silver (III) chemistry can be found in the following book: Chemistry of the Elements, second edition, written by Greenwood and Earnshaw, pages 1181 and 1188.
Precious Metals 16 : 141-149 ( 1992 )
Anti-Pathogenic Silver Molecular
Semiconductors"
Marvin Antelman
Marvin Antelman
"Tetrasilver tetroxide (Ag4O4 ) crystals were prepared by modifying the procedure described by Hammer and Kleinberg in Inorganic Syntheses (IV,12). A stock solution was prepared by dissolving 24.0 grams of potassium peroxydisulfate in distilled water and subsequently adding to this 24.0 of sodium hydroxide and then diluting the entire solution with said water to a final volume of 500 ml. Into 20 ml. vials were weighed aliquots of silver nitrate containing 1.0 g. of silver. Now 50 ml. of the aforementioned stock solution were heated in a 100 ml. beaker, and the contents of one of the vials was added to the solution upon attaining a temperature of 85.degree. C. The beaker was then maintained at 90.degree. C. for 15 minutes. The resulting deep black oxide obtained consisting of molecular crystal devices was washed and decanted four times with distilled water in order to remove impurities. The purified material was collected for further evaluation and comparison with commercial material. The commercial material was purchased from Johnson Matthey's Catalog Chemicals Division of the Aesar Group of Ward Hill, Massachusetts, under product code 11607 and generically listed in its materials Safety Data Sheet as both silver peroxide and silver suboxide, having a purity of 99.9%... "
http://en.wikipedia.org/wiki/Potassium_peroxymonosulfate
Potassium Peroxydisulfate
Potassium peroxymonosulfate (also known as MPS, potassium monopersulfate, and the trade names Caroat and Oxone) is widely used as an oxidizing agent. It is the potassium salt of peroxymonosulfuric acid.
The potassium salt is marketed by two companies: Evonik (formerly Degussa) under the tradename Caroat and DuPont under the tradename Oxone, tradenames which are now part of standard chemistry vocabulary. It is a component of a triple salt with the formula 2KHSO5·KHSO4·K2SO4.[1] The standard electrode potential for this compound is +1.44 V with a half reaction generating the hydrogen sulfate.
HSO5- + 2 H+ + 2 e- ? HSO4- + H2O
Reactions
Oxone is a versatile oxidant. It oxidizes aldehydes to carboxylic acids; in the presence of alcoholic solvents, the esters may be obtained. Internal alkenes may be cleaved to two carboxylic acids, while terminal alkenes may be epoxidized. Thioethers give sulfones, tertiary amines give amine oxides, and phosphines give phosphine oxides.[2]
Illustrative of the oxidation power of this salt is the conversion of an acridine derivative to the corresponding acridine-N-oxide.[3]
It will also oxidize a thioether to a sulfone with 2 equivalents.[4] With one equivalent the reaction converting sulfide to sulfoxide is much faster than that of sulfoxide to sulfone, so the reaction can conveniently be stopped at that stage if so desired.
Uses
Potassium peroxymonosulfate can be used in swimming pools to keep the water clear, thus allowing chlorine in pools to work to sanitize the water rather than clarify the water, resulting in less chlorine needed to keep pools clean.[5]
References
1. "Oxone". Spectral Database for Organic Compounds (SDBS). "National Institute of Advanced Industrial Science and Technology (AIST)". http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/cre_frame_disp.cgi?sdbsno=21455.
2. Benjamin R. Travis, Meenakshi Sivakumar, G. Olatunji Hollist, and Babak Borhan (2003). "Facile Oxidation of Aldehydes to Acids and Esters with Oxone". Organic Letters 5 (7): 1031–4. doi:10.1021/ol0340078. PMID 12659566.
3. Thomas W. Bell, Young-Moon Cho, Albert Firestone, Karin Healy, Jia Liu, Richard Ludwig, and Scott D. Rothenberger (1993), "9-n-Butyl-1,2,3,4,5,6,7,8-Octahydroacridin-4-ol", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv8p0087 ; Coll. Vol. 8: 87
4. James R. McCarthy, Donald P. Matthews, and John P. Paolini (1998), "Reaction of Sulfoxides with Diethylaminosulfur Trifluoride", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv9p0446 ; Coll. Vol. 9: 446
5. "Benefits of Using a Non-Chlorine Shock Oxidizer Powered by DuPont™ Oxone®." Dupont.com. Accessed July 2011.
Applications
DuPont Oxone Monopersulfate Compound Applications : http://www.dupont.com/oxone/applications/index.html
Potassium Monopersulfate – Article on precious metal extraction from distributor Green Controll : http://greencontroll.hu/EN_termekek_7.html
Technical
DuPont Oxone Monopersulfate Compound Technical Information
http://www.dupont.com/oxone/techinfo/index.html
http://www.chemblink.com/products/37222-66-5.htm
Potassium Peroxomonosulfate
Name -- Potassium peroxomonosulfate
Synonyms -- Oxone; Potassium monopersulfate; Potassium monopersulfate triple salt
Molecular Structure -- Potassium peroxomonosulfate, Oxone, Potassium monopersulfate, Potassium monopersulfate triple salt, CAS # -- 37222-66-5
Molecular Formula -- H3K5O18S4
Molecular Weight -- 614.76
CAS Registry Number -- 37222-66-5
Water solubility -- 250 g/L (20 ºC)
Risk Codes -- R34;R37;R8 Details
Safety Description -- S17;S26;S36/37/39;S45 Details
http://www.marantec.com [ defunct ]
Technical Description of "Electron Jumping
Compounds" (EJC)
* Covalent bonding with the target
* Release of electrical energy (nano-electrocution) through a reduction/oxidation process
* Release of highly active singlet oxygen. This action effectively ensures the target’s death. No other drug or anti-microbial functions in this way. The unique method of action of the Company’s compounds has the potential to establish a new class of medicine.
Beyond Antibiotics, Non Toxic Disinfectants and Tetrasil
In this paper, it was reported that the effects of the electron transfer involved with respect to the tetroxide, rendered it a more powerful germicide than other silver entities. The instant inventor holds patents for multivalent silver antimicrobials, e.g., U.S. Pat. No. 5,017,295 for Ag(II) and U.S. Pat. No. 5,223,149 for Ag (III); and while these entities are stronger antimicrobials than Ag (I) compounds, they pale by comparison to the tetroxide and so does colloidal silver that derives its germicidal properties from trace silver (I) ions it generates in various environments. Accordingly, the oligodynamic properties of these entities may be summarized as follows, which is referred to as the Horsfal series:
Ag4O4 > Ag(III) > Ag(II) >>>> Ag(I)
The other unique property of the tetroxide was that it did not stain organic matter such as skin in like manner as Ag(I) compounds do. In addition, it was light stable.
If we are to consider one molecular device in operation, then each molecule would release two electrons having each a charge of 4.8 x 10-10 e.s.u. equivalent to approximately 1.6 x 10-19 coulombs. The EMF given in my Encyclopedia of Chemical Electrode Potentials (Plenum 1982), page 88, for the oxidation of Ag(I) to Ag(II) is 1.98 volts which approximates 2.0 V. The total power output per device can be calculated in watts by multiplying the power output for each electron by 2. Since power is the product of the potential times the charge, P = EI; for each electron it would be
2.0 x 1.6 x 10^-19 = 3.2 x 10^-19 watts
From this, and using Avogadro's number, we can calculate that the power flux of one liter of solution containing 0.5 PPM of devices would be 0.064 watts.
Since the electronic charges of the devices are directly proportional to the number of devices in solution, i.e., the concentration of the oxide in the solution, we can arbitrarily assign our own device power flux constant which can be used to gauge the concentrations of the devices required in order to kill particular organisms in specific environments. I have found the following formula useful for this purpose:
Power Flux = EMF generated per molecule x Concentration x 5 (the EMF being 4.0 volts per molecular device; and the concentration is in PPM).
Utilizing this formula, the power flux to effectuate 100% kills for the following organisms is given in Table I which follows.
TABLE I
______________________________________
Organism Name Power Flux
______________________________________
Escherichia coli 50.0
Staphylococcus aureus
50.0
Streptococcus faecalis
50.0
Streptococcus pyogenes
50.0
Candida albicans 50.0
Pseudomonas aeruginosa
25.0
Micrococcus luteus 25.0
Staphylococcus epidermidis
12.5
When the tetroxide crystals are utilized to destroy pathogens, they will not do so unless activated by an oxidizing agent. This is analogous to the behavior of single semiconducting photovoltaic molecular devices such as copper indium selenide whose surfaces must be "etched" in order to activate the photovoltaic activity, i.e., for light to facilitate the release of electrons from the molecule. The tetroxide was activated by persulfates [ or: hydrogen peroxide ]. It was found that when the persulfates were tested as a control by themselves, they failed to exhibit any unilateral antipathogenic activity at the optimum level selected of 10 PPM. The persulfates evaluated varied from OXONE (Registered Trademark Du Pont Company) brand potassium monopersulfate to alkali peroxydisulfates.
The oxidizing agent to activate the crystals for water supplies would be OXONE (Registered Trademark Du Pont Company) or hydrogen peroxide.
https://www.youtube.com/watch?v=i-nI19OLyMM
Tetrasil, tetrasilver-tetroxide, silver
oxide
Tetrasilver tetroxide - prepared at home. I prepared it from AgNO3, NaOH and NaS2O8. I dissolved it in neutral organic solvent and applied against my athletes feet twice and it worked-signs disappeared.
https://pubchem.ncbi.nlm.nih.gov/compound/44150047
Tetrasilver tetraoxide
PubChem CID: 44150047
Chemical Names: Tetrasilver tetraoxide; Silver oxide (Ag4O4); 155645-89-9; IN001522; TETRASILVER(1+) ION TETRAOXIDANDIIDE More...
Molecular Formula: Ag4O4-4
Molecular Weight: 495.469 g/mol
InChI Key: VETQHSSYYACILD-UHFFFAOYSA-N
IUPAC Name : tetrasilver;oxygen(2-)
InChI : InChI=1S/4Ag.4O/q4*+1;4*-2
InChI Key : VETQHSSYYACILD-UHFFFAOYSA-N
Canonical SMILES : [O-2].[O-2].[O-2].[O-2].[Ag+].[Ag+].[Ag+].[Ag+]
Molecular Formula
Ag4O4-4
Other Identifiers
CAS 155645-89-9
Synonyms
Tetrasilver tetraoxide
Silver oxide (Ag4O4)
155645-89-9
IN001522
TETRASILVER(1+) ION TETRAOXIDANDIIDE
Chemical and Physical Properties
Property Name Property Value
Molecular Weight 495.469 g/mol
Hydrogen Bond Donor Count 0
Hydrogen Bond Acceptor Count 4
Rotatable Bond Count 0
Complexity 0
Topological Polar Surface Area 4 A^2
Monoisotopic Mass 491.6 g/mol
Exact Mass 495.599 g/mol
Compound Is Canonicalized true
Formal Charge -4
Heavy Atom Count 8
Defined Atom Stereocenter Count 0
Undefined Atom Stereocenter Count 0
Defined Bond Stereocenter Count 0
Undefined Bond Stereocenter Count 0
Isotope Atom Count 0
Covalently-Bonded Unit Count 8
Description
Trade Name : Silver ( II ) Oxide
Product Names : Tetrasil, Sildate, etc.
Chemical Abstact Service ( CAS ) Number : 1301-96-8
EPA Chemical Code : 129097
EPA Registration Number : 3432-64
Chemical Family : metal Oxide
Molar weight :
Density : 7.48
Odor : odorless
Melting Point : 100 C. ( decomposes )
Solubility : practically insoluble -- 0.025 gr./100 mL.
Dissociation Constant : Ka = 7.9 x 10^-13
Stability : store below 100 C ( decomposition )
Oxidizer/Reducer Action : strong oxidizer
Non-Flammable
Corrosion Characteristics : corrosive to metals
Names : Silver(ll)Oxide // Silver(l,lll)Oxide // Argentic Oxide // Tetrasil // Sildate // Divasil // Silver Peroxide // Silver suboxide // Divalient Silver Oxide // Mono Trivalient Silver oxide // Tetrasilver Tetroxide
Can be shipped US Postal Service 1 oz. or less with no hazard packaging in dark glass containers suitably protected from breakage.
NOT to be confused with :
Ag2O // Silver(l)Oxide // Silver Monoxide // Silver rust // Argentic Oxide // Argentious Oxide
Molar weight : 231.74
Density 7.14
Melting point 280 C
Photo sensitive
CAS Registry Number : 20667-12-3
Water soluble : 0 .00027 g/100 mL
Molecular weight : 495.52
Dissociation Constant : KA 7.9 x 10-13
Both forms of silver oxide are strong oxidants and will ignite upon contact with sulfur, red phosphorous, sulfides of antimony and arsenic, and will ignite inflammable substances. Reacts explosively with Ammonia and Hydrogen Peroxide, forming silver powder and oxygen ( YouTube : http://www.youtube.com/watch?v=Vt4hrnY9h2I& feature=player_embedded )
Toxicology Characteristics
Results of acute dermal toxicity study for this product ( 2% Active Ingredient ) indicates Toxicity Category III (CAUTION ). Additional toxicological studies supporting this registration indicate Toxicity Category IV. Adverse effects to human health are not anticipated from the use of this product.
Ecological effects data indicate the product is practically non-toxic to avian species and highly toxic to aquatic species.
Environmental fate data indicate that the compound does not hydrolyze.
Use Patterns & Formulations
A disinfectant for use in swimming pool water
Types & Methods of Applications : For direct addition to swimming pool water followed by addition of a potassium persulfate activator compound ( Oxone )
Application Rates : 1 ppm ( 1 oz / 10,000 gallons water )
A 3% concentrate was used and evaluated by a certified laboratory employing good laboratory practice (GLP) according to the Code of Federal Regulations for this purpose. The results were as follows:
Acute Oral Toxicity : LD.sub.50 Greater than 5,000 mg/Kg
Acute Dermal Toxicity : LD.sub.50 Greater than 2,000 mg/Kg
Primary Eye Irritation : Mildly irritating
Primary Skin Irritation : No irritation
Skin Sensitization : Non-Sensitizing
http://81.207.88.128/science/chem/exps/Ni+persulfate/index.html
Oxidation of silver to its +3 oxidation
state.
Prepare a solution of silver nitrate or silver oxide in dilute nitric acid. Any concentration of 1 to 2 mol/l for the nitric acid is OK.
Add some solid sodium persulfate to the liquid. Adding a fairly concentrated solution of sodium persulfate also works. When this is done, then the liquid becomes brown and remains clear. The brown color is due to silver (III) ions. The brown color is formed quickly, although not instantaneously. It takes a few seconds.
The two pictures below show the brown liquid and a small quantity of this liquid, diluted in some dilute nitric acid. These picture clearly show the brown color of silver (III) ions (*). (*) see remark below.
Silver (III) ions are not very stable. Even in the fairly strongly acidic liquids, the compound slowly decomposes. A black precipitate is formed and oxygen is released very slowly. This black precipitate is due to combined hydrolysis and reduction of the silver (III) ions. A mixed silver (I) silver (III) oxide is formed, which precipitates from the liquid as a black solid.
Remarkably, when persulfate is added to a neutral solution of silver nitrate, then no brown color is formed. In that case the liquid first remains colorless, but in the course of a few minutes it slowly turns turbid and a dark brown/black precipitate is formed. Apparently, at higher pH, the brown silver (III) ion is not formed at all and the mixed silver (I) silver (III) oxide is formed immediately.
Addition of sodium hydroxide, quick formation of Ag(I)Ag(III)O2
When the brown liquid is added to a solution of sodium hydroxide, then the process of formation of the black silver (I) silver (III) oxide is almost immediate. As soon as the brown liquid is added to a solution of sodium hydroxide, a dark brown very finely divided precipitate is formed. The solid particles stick together quickly and larger black particles are formed. The black solid slowly evolves oxygen and every few minutes it moves to the surface, due to many small bubbles of oxygen, which are trapped inside the precipitate. When these small bubbles of oxygen are lost, then the solid mass sinks to the bottom again. This 'dance' is repeated several times.
The three pictures below show the liquid, immediately after adding it to a slight excess amount of a solution of NaOH. The second picture shows the same liquid a few minutes later, when the particles of the precipitate stick to each other. The final picture shows the precipitate near the surface, due to lots of trapped bubbles of oxygen. All the pictures clearly show the bubbles of oxygen.
Discussion of the results
Here, the reactions with nickel (II) and silver (I) are covered separately.
Reaction with nickel
Persulfate oxidizes nickel hydroxide to nickel (IV) oxide in water.
Ni(OH)2 + 2OH– + S2O82- ? NiO2 + 2SO42- + 2H2O
In the wet environment, the compound NiO2 does not exist as such, as suggested by the simplified equation, given above. In fact a non-stoichiometric compound, which can best be described as NiO2.nH2O is formed, with n some indeterminate number.
On acidification with nitric acid or sulphuric acid, the nickel (IV) compound decomposes again:
2NiO2.nH2O(s) + 4H+(aq) ? 2Ni2+(aq) + O2(g) + 2H2O + nH2O
When dilute hydrochloric acid is added, then the liquid gives a strong smell of chlorine. In that case, the chloride ion is oxidized to chlorine. The liquid still bubbles in that case. Probably there will be oxidation of chloride to chlorine and still the decomposition reaction, as described above.
Reaction with silver
In acidic media, persulfate is capable of oxidizing silver (I) ions to silver (III) ions. These silver (III) ions are brown.
Ag+(aq) + S2O82-(aq) ? Ag3+(aq) + 2SO42-(aq)
Silver (III) ions are not very stable. This liquid slowly looses its color and gives off oxygen. A black precipitate is formed of silver (I) silver (III) oxide. The silver (III) ions slowly oxidize the water, in which they are dissolved.
4Ag3+ + 6H2O ? 2AgIAgIIIO2 + 12H+ + O2
When the liquid is made more basic, then the reaction proceeds much faster, as the experiment demonstrates. The following reaction occurs in that case.
4Ag3+ + 12OH– ? 2AgIAgIIIO2 + 6H2O + O2
The compound AgAgO2 in turn also decomposes. It slowly looses oxygen and is converted to simple silver (I) oxide.
2AgIAgIIIO2 ? 2AgI2O + O2
(*) Remark: Whether the brown color is due to plain Ag3+ or due to some mixed valency complex of silver (I) and silver (III) is not clear to me. It might be that the brown color is due to a mixed valency complex of silver (I) and silver (III). Examples of mixed valency complexes are also given on the following pages: copper (I) / copper (II) and titanium (III) / titanium (IV).
General remarks
Both the silver (III) compounds and the NiO2 compound are very strong oxidizers. Both compounds are capable of oxidizing manganese (IV) and manganese (II) to the +7 oxidation state as permanganate and chromium (III) is oxidized to the +6 oxidation state as dichromate or chromate.
Silver nitrate is a catalyst in many reactions with persulfate in acidic media. Persulfate is a strong oxidizer, but it also is somewhat sluggish. The reaction between silver (I) and persulfate in acidic media, however is quite fast. Silver (III) in turn reacts with manganese (II) or chromium (III) quickly to form permanganate or dichromate, itself being converted to silver (I) again. So, in the presence of a small amount of silver nitrate, the persulfate anion can be used as a fast and very strong oxidizer. The catalytic action of silver is based on the fact that an other pathway for the final redox reaction is provided, with Ag3+ as intermediate species.
A similar catalytic action can be observed with nickel hydroxide in basic solutions. The reaction between nickel hydroxide and persulfate is very fast (instantaneously, at least in terms of human observation). Nickel (IV) oxide in turn is capable of oxidizing e.g. manganese (IV) oxide to permanganate. This property can be used as a sensitive method for detecting manganese.
Another important remark is that in both experiments, the presence of chloride ions should be avoided. Especially with the silver experiment, chloride ions are really disturbing. They make the liquid cloudy, due to formation of silver (I) chloride and they interfere, due to oxidation to chlorine.
For the nickel experiment the presence of chloride is not of a direct concern, but if one wants to use NiO2 for detection of manganese by conversion to the deep purple permanganate, then even small amounts of chloride interfere and make the detection fail.
More info on the interesting and remarkable subject of silver (III) chemistry can be found in the following book: Chemistry of the Elements, second edition, written by Greenwood and Earnshaw, pages 1181 and 1188.
http://www.groupsrv.com/science/about69879.html
Dec 09, 2004 11:23 am
Does anyone know an easy method of producing silver oxide Ag4O4? Other names for this compound are polyvalent silver oxide, Divalent silver
oxide, Sildate, tetrasilver tetraoxide, silver II oxide and CAS #155645-89-9
Thanks,
Marshall
Dec 09, 2004 3:01 pm
I think it is the guy who hopes that this magic remedy "tetrasilver tetraoxide" will cure his cancer. He was trying to hire some chemist here on usenet to make it for him. All on can get from this cure is a nice gray shade in the face from Ag poisoning. (The medical term is argiria.)
I think it is everybody's right to do Darwin award experiments on himself as long as nobody else gets involved. Stay away from this ass.
Dec 09, 2004 3:46 pm
According to the book "Chemistry of the Elements" of Greenwood, the compound silver (II) oxide is not a true silver (II) compound, but a mixed oxidation state silver (I) silver (III) oxide, hence AgO can better be described as Ag(I)Ag(III)O2, or if you wish Ag(I)2 Ag(III)2 O4.
Silver (III) compounds can even be formed in solution by dissolving some silver nitrate in dilute nitric acid and adding a solution of sodium persulfate or potassium persulfate. The solution becomes brown and remains clear. After a while, however, it becomes lighter again and while doing so, it slowly produces oxygen (I think the Ag(3+) oxidizes the water). I'm not sure whether the brown ion is plain aqueous Ag(3+) or a mixed valency compound of Ag(3+) and Ag(+). When the solution is not sufficiently acidic, then a black precipitate is formed of the above mentioned silver (I) silver (III) oxide.
Dec 09, 2004 4:05 pm
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I think it is the guy who hopes that this magic remedy "tetrasilver tetraoxide" will cure his cancer.
What guy? I have not seen any references to cancer here. I certainly do not have cancer. It is insoluble in water, so how would one cure cancer with it?
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He was trying to hire some chemist here on usenet to make it for him.
Why would anyone do that when it can be purchased?
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All on can get from this cure is a nice gray shade in the face from Ag poisoning. (The medical term is argiria.)
First it is argyria, not argiria. Second it is not silver poisoning, it is silver deposits in the skin which is only a cosmetic condition.
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I think it is everybody's right to do Darwin award experiments on himself as long as nobody else gets involved. Stay away from this ass.
Just who are you talking about?
According to the book "Chemistry of the Elements" of Greenwood, the compound silver (II) oxide is not a true silver (II) compound, but a mixed oxidation state silver (I) silver (III) oxide, hence AgO can better be described as Ag(I)Ag(III)O2, or if you wish Ag(I)2 Ag(III)2 O4.
That is correct. There are two Ag+ and two Ag+++ in Ag4O4. I have found this documented elsewhere as well.
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Silver (III) compounds can even be formed in solution by dissolving some silver nitrate in dilute nitric acid and adding a solution of sodium persulfate or potassium persulfate. The solution becomes brown and remains clear. After a while, however, it becomes lighter again and while doing so, it slowly produces oxygen (I think the Ag(3+) oxidizes the water). I'm not sure whether the brown ion is plain aqueous Ag(3+) or a mixed valency compound of Ag(3+) and Ag(+). When the solution is not sufficiently acidic, then a black precipitate is formed of the above mentioned silver (I) silver (III) oxide.
Somewhat similar results can be obtained by mixing a dilute solution of silver hydroxide and hydrogen peroxide from experiments I have run...
http://pubs.acs.org/doi/abs/10.1021/ed085p863
J. Chem. Educ., 2008, 85 (6), p 863
DOI: 10.1021/ed085p863
Silver(II) Oxide or Silver(I,III) Oxide?
David Tudela
AbstractDavid Tudela
The often called silver peroxide and silver(II) oxide, AgO or Ag2O2, is actually a mixed oxidation state silver(I,III) oxide. A thermochemical cycle, with lattice energies calculated within the "volume-based" thermodynamic approach, explain why the silver(I,III) oxide is more stable than the hypothetical silver(II) oxide. The coordination geometries of silver and copper in their known oxides correlate with those associated to their electron configurations in coordination compounds. The second ionization energy is higher for Ag than for Cu, which can be related to the small size of 3d orbitals and the resulting high electron repulsion for the first transition series elements.
http://pubs.acs.org/doi/abs/10.1021/ja01333a016?src=recsys
Journal of the American Chemical Society, 1933 55 (6), pp 2311–2325
The Solubility of Silver Oxide in Water, in
Alkali and in Alkaline Salt Solutions
Johnston, Cuta, Garrett
Johnston, Cuta, Garrett
http://pubs.acs.org/doi/abs/10.1021/j150267a005?src=recsys
The Journal of Physical Chemistry 1926 30
(9), pp 1179–1180
Solubility of Silver Oxide
Solubility of Silver Oxide
http://pubs.acs.org/doi/abs/10.1021/ed021p523?src=recsys
Journal of Chemical Education, 1944 21
(11), p 523
The oxidation states of silver
The oxidation states of silver
http://pubs.acs.org/doi/abs/10.1021/ja01492a006?src=recsys
Journal of the American Chemical Society, 1960 82 (7), pp 1540–1543
The Thermal Decomposition of Silver Oxide
Herley, Prout
Herley, Prout
http://pubs.acs.org/doi/abs/10.1021/j100078a009?src=recsys
J. Phys. Chem., 1994, 98 (27), pp 6699–6703
DOI: 10.1021/j100078a009
Electronegativity and Bond Type. 2.
Evaluation of Electronegativity Scales
Gordon Sproul
Gordon Sproul
http://earth1.epa.gov/pesticides/foia/reviews/129097/129097-001.pdf
EFFICACY EVALUATION AND TECHNICAL MANAGEMENT SECTION
EFFICACY REVIEW
ANTIMICROBIAL PROGRAM BRANCH
IN 06/30/95 OUT 10/05/95
EPA Reg. No. or File Symbol 3432-AU
LAN Code
EPA Petition or EUP No. OPP Identification Number 165250
Date Division Received 06-16-95
Type Product Swimming Pool Water Disinfectant
MRID No (s) 431365-01. 434656-01. & 434583-02
Product Manager PM 32 (Douglas)
Product Name SILDATE
Company Name N. Jonas & Co.
Submission Purpose Application for New Registration with
Field Test Data and proposed label
Type Formulation Liquid
Active Ingredient (s); —%—
Silver Oxide II (AgO) 2. 05
Contains 2.73 Ounce Silver Oxide II. Equivalent to 2.38 ounce Silver as Elemental per Gallon.
Activator
Energize (Potassium Persulfate) (1 pound per 10,000 gallons)
Recommendations
Efficacy Supported By The Data:
The submitted Field Test data are acceptable and meet the efficacy data requirements/criteria established by the Environmental Protection Agency for Swimming Pool Water Disinfectants as outlined in the Pesticide Assessment Guidelines, Subdivision G - Product Performance 91-8(c) at a concentration of 1 ppm Sildate in the presence of 10 ppm Energize.
Labeling
Under the heading "Directions for Use", in the first paragraph, revise the statement " — add Energize at the rate of 1 lb per 10,000 swimming pool water" to read "...add Energize at the rate of 1 lb per 10,000 gallons of swimming pool water." Under the heading "Directions for Use", in the third paragraph, revise the statement "If the pool volume is knot known " to read "If the pool volume is not known..." Include Ingredient Statement on Energize label and specify percent Potassium persulfate.
Reviewed by Srinivas Gowda Date 10/05/95
Basic Chemical Information for Silver oxide (Ag4O4)
Chemical Name
Silver oxide (Ag4O4
Microbiocide, Fungicide, Herbicide
Synonyms
Chemical versus Common Names
129097 (US EPA PC Code) , 1301-96-8 (CAS Number) , 1301968 , 1301968 (CAS Number) , 155645-89-9 (CAS Number) , 155645899 , 155645899 (CAS Number) , Divalent silver oxide (silver II oxide) , Sildate , Silver oxide (Ag4O4) , Silver oxide (Ag4O4) (9CI) (CA INDEX NAME) , Silver(II) oxide , SilveroxideAg4O4 , Tetrasilver tetraoxide (Ag4O4)
http://www.scorecard.org/chemical-profiles/product.tcl?reg_nr=00343200064&prod_name=SILDATE
CHEMICAL PROFILES Product Profile
Product: SILDATE
EPA Registration Number: 00343200064
This pesticide is used as a: DISINFECTANT
This pesticide is registered for unrestricted use.
This pesticide's toxicity code is 3, which corresponds to a toxicity category of Caution.
Active Ingredients in this Product Percentage by Mass
SILVER OXIDE (AG4O4) 2%