Silver nitrate

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Silver nitrate
Skeletal formula of silver nitrate
Sample of silver nitrate
Identifiers
CAS number 7761-88-8 YesY
PubChem 24470 YesY
ChemSpider 22878 YesY
UNII 95IT3W8JZE YesY
EC-number 231-853-9
UN number 1493
ChEBI CHEBI:32130 YesY
ChEMBL CHEMBL177367 YesY
RTECS number VW4725000
ATC code D08AL01
Jmol-3D images Image 1
Properties
Molecular formula AgNO3
Molar mass 169.87 g mol−1
Appearance White solid
Odor Odorless
Density 4.35 g/cm3 (24 °C)
3.97 g/cm3 (210 °C)[1]
Melting point 209.7 °C (409.5 °F; 482.8 K)[1][3]
Boiling point 440 °C (824 °F; 713 K)
decomposes[1]
Solubility in water 122 g/100 mL (0 °C)
170 g/100 mL (10 °C)
256 g/100 mL (25 °C)
373 g/100 mL (40 °C)
912 g/100 mL (100 °C)[2]
Solubility Soluble in acetone,[1] ammonia, ether, glycerol
Solubility in acetic acid 0.776 g/kg (30 °C)
1.244 g/kg (40 °C)
5.503 g/kg (93 °C)[3]
Solubility in acetone 0.35 g/100 g (14 °C)
0.44 g/100 g (18 °C)[2]
Solubility in benzene 0.22 g/kg (35 °C)
0.44 g/kg (40.5 °C)[2]
Solubility in ethanol 3.1 g/100 g (19 °C)[2]
Solubility in ethyl acetate 2.7 g/100 g (20 °C)[3]
log P 0.19[4]
Magnetic susceptibility −4.57·10−5 cm3/mol[1]
Refractive index (nD) 1.744
Viscosity 3.77 cP (244 °C)
3.04 cP (275 °C)[3]
Structure
Crystal structure Orthorhombic, oP56[5]
Space group P212121, No. 19[5]
Point group 222[5]
Lattice constant a = 6.992(2) Å, b = 7.335(2) Å, c = 10.125(2) Å[5]
Lattice constant α = 90°, β = 90°, γ = 90°
Thermochemistry
Specific
heat capacity
C
93.1 J/mol·K[1]
Std molar
entropy
So298
140.9 J/mol·K[1]
Std enthalpy of
formation
ΔfHo298
−124.4 kJ/mol[1]
Gibbs free energy ΔG −33.4 kJ/mol[1]
Hazards
GHS pictograms The flame-over-circle pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)The environment pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[6]
GHS signal word Danger
GHS hazard statements H272, H314, H410[6]
GHS precautionary statements P220, P273, P280, P305+351+338, P310, P501[6]
EU classification Oxidizing Agent O Corrosive C Dangerous for the Environment (Nature) N
R-phrases R8, R34, R50/53
S-phrases S26, S36/37/39, S45, S60, S61
Main hazards Explosively reacts with ethanol. Corrosive.
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g., fluorine Special hazard OX: Oxidizer. E.g., potassium perchlorateNFPA 704 four-colored diamond
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Silver nitrate is an inorganic compound with chemical formula AgNO
3
. This compound is a versatile precursor to many other silver compounds, such as those used in photography. It is far less sensitive to light than the halides. It was once called lunar caustic because silver was called luna by the ancient alchemists, who believed that silver was associated with the moon.[7]

In solid silver nitrate, the silver ions are three-coordinated in a trigonal planar arrangement.[5]

Discovery[edit]

Albertus Magnus, in the 13th century, documented the ability of nitric acid to separate gold and silver by dissolving the silver.[8] Magnus noted that the resulting solution of silver nitrate could blacken skin. Its common name at the time was nitric acid silver.

Synthesis[edit]

Silver nitrate can be prepared by reacting silver, such as a silver bullion or silver foil, with nitric acid, resulting in silver nitrate, water, and oxides of nitrogen. Reaction byproducts depend upon the concentration of nitric acid used.

3 Ag + 4 HNO3 (cold and diluted) → 3 AgNO3 + 2 H2O + NO
Ag + 2 HNO3 (hot and concentrated) → AgNO3 + H2O + NO2

This is performed under a fume hood because of toxic nitrogen oxide(s) evolved during the reaction.[9]

Reactions[edit]

A typical reaction with silver nitrate is to suspend a rod of copper in a solution of silver nitrate and leave it for a few hours. The silver nitrate reacts with copper to form hairlike crystals of silver metal and a blue solution of copper nitrate:

2 AgNO3 + Cu → Cu(NO3)2 + 2 Ag

Silver nitrate decomposes when heated:

2 AgNO3(l) → 2 Ag(s) + O2(g) + 2 NO2(g)

Qualitatively, decomposition is negligible below the melting point, but becomes appreciable around 250° C and totally decompose at 440° C. [10]

Most metal nitrates thermally decompose to the respective oxides, but silver oxide decomposes at a lower temperature than silver nitrate, so the decomposition of silver nitrate yields elemental silver instead.

Uses[edit]

Precursor to other silver compounds[edit]

Silver nitrate is the least expensive salt of silver; it offers several other advantages as well. It is non-hygroscopic, in contrast to silver fluoroborate and silver perchlorate. It is relatively stable to light. Finally, it dissolves in numerous solvents, including water. The nitrate can be easily replaced by other ligands, rendering AgNO3 versatile. Treatment with solutions of halide ions gives a precipitate of AgX (X = Cl, Br, I). When making photographic film, silver nitrate is treated with halide salts of sodium or potassium to form insoluble silver halide in situ in photographic gelatin, which is then applied to strips of tri-acetate or polyester. Similarly, silver nitrate is used to prepare some silver-based explosives, such as the fulminate, azide, or acetylide, through a precipitation reaction.

Treatment of silver nitrate with base gives dark grey silver oxide:[11]

2 AgNO3 + 2 NaOH → Ag2O + 2 NaNO3 + H2O

Halide abstraction[edit]

The silver cation, Ag+
, reacts quickly with halide sources to produce the insoluble silver halide, which is a cream precipitate if Br- is used, a white precipitate if Cl
is used and a yellow precipitate if I
is used. This reaction is commonly used in inorganic chemistry to abstract halides:

Ag+
+ X
(aq) → AgX

where X
= Cl
, Br
, or I
.

Other silver salts with non-coordinating anions, namely silver tetrafluoroborate and silver hexafluorophosphate are used for more demanding applications.

Similarly, this reaction is used in analytical chemistry to confirm the presence of chloride, bromide, or iodide ions can be tested by adding silver nitrate solution. Samples are typically acidified with dilute nitric acid to remove interfering ions, e.g. carbonate ions and sulfide ions. This step avoids confusion of silver sulfide or silver carbonate precipitates with that of silver halides. The color of precipitate varies with the halide: white (silver chloride), pale yellow/cream (silver bromide), yellow (silver iodide). AgBr and especially AgI photo-decompose to the metal, as evidence by a grayish color on exposed samples.

Organic synthesis[edit]

Silver nitrate is used in many ways in organic synthesis, e.g. for deprotection and oxidations. Ag+
binds alkenes reversibly, and silver nitrate has been used to separate mixtures of alkenes by selective absorption. The resulting adduct can be decomposed with ammonia to release the free alkene.[12]

Biology[edit]

In histology, silver nitrate is used for silver staining, for demonstrating reticular fibers, proteins and nucleic acids. For this reason it is also used to demonstrate proteins in PAGE gels. It can be used as a stain in scanning electron microscopy.[13]

Medicine[edit]

Micrograph showing a silver nitrate (brown) marked surgical margin.

Silver salts have antiseptic properties. Until the development and widespread adoption of antibiotics, dilute solutions of AgNO3 used to be dropped into newborn babies' eyes at birth to prevent contraction of gonorrhea from the mother. Eye infections and blindness of newborns was reduced by this method; incorrect dosage, however, could cause blindness in extreme cases. This protection was first used by Credé in 1881.[14][15][16] Fused silver nitrate, shaped into sticks, was traditionally called "lunar caustic". It is used as a cauterizing agent, for example to remove granulation tissue around a stoma. General Sir James Abbott noted in his journals that in India in 1827 it was infused by a British surgeon into wounds in his arm resulting from the bite of a mad dog to cauterize the wounds and prevent the onset of rabies.[17] Dentists sometimes use silver nitrate infused swabs to heal oral ulcers. Silver nitrate is also used by some podiatrists to kill cells located in the nail bed. Silver nitrate is also used to cauterize superficial blood vessels in the nose to help prevent nose bleeds.

The Canadian physician C. A. Douglas Ringrose researched the use of silver nitrate for sterilization procedures on women. A specialist in obstetrics and gynaecology, Ringrose believed that the corrosive properties of silver nitrate could be used to block and corrode the fallopian tubes, in a process that he called "office tubal sterilization".[18] The technique was ineffective; in fact at least two women underwent abortions. Ringrose was sued for malpractice, although these suits were unsuccessful.[19]

Disinfection[edit]

Much research has been done in evaluating the ability of the silver ion at inactivating Escherichia coli, a microorganism commonly used as an indicator for fecal contamination and as a surrogate for pathogens in drinking water treatment. Concentrations of silver nitrate evaluated in inactivation experiments range from 10–200 micrograms per liter as Ag+. Silver's antimicrobial activity saw many applications prior to the discovery of modern antibiotics, when it fell into near disuse. Its association with argyria made consumers wary and led them to turn away from it when given an alternative.

Against warts[edit]

Skin on hand stained by silver nitrate

Repeated daily application of silver nitrate can induce adequate destruction of cutaneous warts, but occasionally pigmented scars may develop. In a placebo-controlled study of 70 patients, silver nitrate given over nine days resulted in clearance of all warts in 43% and improvement in warts in 26% one month after treatment compared to 11% and 14%, respectively, in the placebo group.[20]

Safety[edit]

As an oxidant, silver nitrate should be properly stored away from organic compounds. Despite its common usage in extremely low concentrations to prevent gonorrhea and control nose bleeds, silver nitrate is still very much toxic and corrosive.[21] Brief exposure will not produce any immediate side effects other than the purple, brown or black stains on the skin, but upon constant exposure to high concentrations, side effects will be noticeable, which include burns. Long-term exposure may cause eye damage. Silver nitrate is known to be a skin and eye irritant.

Silver nitrate is currently unregulated in water sources by the Environmental Protection Agency. However, if more than 1 gram of silver is accumulated in the body, a condition called argyria may develop. Argyria is a permanent cosmetic condition in which the skin and internal organs turn a blue-gray color. The United States Environmental Protection Agency used to have a maximum contaminant limit for silver in water until 1990, when it was determined that argyria did not impact the function of any affected organs.[22] Argyria is more often associated with the consumption of colloidal silver solutions rather than with silver nitrate, since it is only used at extremely low concentrations to disinfect the water. However, it is still important to be wary before ingesting any sort of silver-ion solution.

References[edit]

  1. ^ a b c d e f g h i Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0. 
  2. ^ a b c d Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). New York: D. Van Nostrand Company. p. 617–619. 
  3. ^ a b c d Anatolievich, Kiper Ruslan. "silver nitrate". http://chemister.ru. Retrieved 2014-07-20. 
  4. ^ a b "MSDS of Silver sulfate". https://www.fishersci.ca. Fair Lawn, New Jersey: Fisher Scientific, Inc. Retrieved 2014-07-20. 
  5. ^ a b c d e Meyer, P.; Rimsky, A.; Chevalier, R. (1978). B. "Structure du nitrate d'argent à pression et température ordinaires. Example de cristal parfait". Acta Crystallographica 34 (5): 1457–1462. doi:10.1107/S0567740878005907. 
  6. ^ a b c Sigma-Aldrich Co., Silver nitrate. Retrieved on 2014-07-20.
  7. ^ "Definition of Lunar Caustic". dictionary.die.net. 
  8. ^ Szabadváry, Ferenc (1992). History of analytical chemistry. Taylor & Francis. p. 17. ISBN 2-88124-569-2. 
  9. ^ "Making silver nitrate". http://www.youtube.com. YouTube. 
  10. ^ Stern, K. H. (1972). "High Temperature Properties and Decomposition of Inorganic Salts Part 3, Nitrates and Nitrites". Journal of Physical and Chemical Reference Data 1 (3): 747. doi:10.1063/1.3253104.  edit
  11. ^ Campaigne, E.; LeSuer, W. M. (1963), "3-Thiophenecarboxylic (Thenoic) Acid", Org. Synth. ; Coll. Vol. 4: 919  (preparation of Ag2O, used in oxidation of an aldehyde)
  12. ^ Cope, A. C.; Bach, R. D. (1973), "trans-Cyclooctene", Org. Synth. ; Coll. Vol. 5: 315 
  13. ^ Geissinger HD (2011). "The use of silver nitrate as a stain for scanning electron microscopy of arterial intima and paraffin sections of kidney". Journal of Microscopy 95 (3): 471–481. doi:10.1111/j.1365-2818.1972.tb01051.x. PMID 4114959. 
  14. ^ Peter.H (2000). "Dr Carl Credé (1819–1892) and the prevention of ophthalmia neonatorum". Arch Dis Child Fetal Neonatal 83 (2): F158–F159. doi:10.1136/fn.83.2.F158. PMC 1721147. PMID 10952715. 
  15. ^ Credé C. S. E. (1881). "Die Verhürtung der Augenentzündung der Neugeborenen". Archiv für Gynaekologie 17 (1): 50–53. doi:10.1007/BF01977793. 
  16. ^ Schaller, Ulrich C. and Klauss, Volker (2001). "Is Credé’s prophylaxis for ophthalmia neonatorum still valid?". Bulletin of the World Health Organization 79 (3): 262–266. doi:10.1590/S0042-96862001000300017. 
  17. ^ British Library, India Office Records, European Manuscripts, MSS EUR F171/33/3, page 109.
  18. ^ Ringrose CA. (1973). "Office tubal sterilization". Obstetrics and Gynecology 42 (1): 151–5. PMID 4720201. 
  19. ^ Cryderman v. Ringrose (1978), 89 D.L.R. (3d) 32 (Alta S.C.) and Zimmer et al. v. Ringrose (1981) 4 W.W.R. 75 (Alta C.A.).
  20. ^ Sterling, J. C.; Handfield-Jones, S.; Hudson, P. M.; British Association of Dermatologists (2001). "Guidelines for the management of cutaneous warts". British Journal of Dermatology 144 (1): 4–11. doi:10.1046/j.1365-2133.2001.04066.x. PMID 11167676.  edit
  21. ^ "Safety data for silver nitrate (MSDS)". Oxford University Chemistry department. 
  22. ^ "Silver Compounds." Encyclopedia of Chemical Technology. Vol. 22. Fourth Ed. Excec. Ed. Jaqueline I. Kroschwitz. New York: John Wiley and Sons, 1997.

External links[edit]

Salts and the ester of the Nitrate ion
HNO3 He
LiNO3 Be(NO3)2 B(NO3)4- RONO2 NO3-
NH4NO3
O FNO3 Ne
NaNO3 Mg(NO3)2 Al(NO3)3 Si P S ClONO2 Ar
KNO3 Ca(NO3)2 Sc(NO3)3 Ti(NO3)4 VO(NO3)3 Cr(NO3)3 Mn(NO3)2 Fe(NO3)3 Co(NO3)2,
Co(NO3)3
Ni(NO3)2 Cu(NO3)2 Zn(NO3)2 Ga(NO3)3 Ge As Se Br Kr
RbNO3 Sr(NO3)2 Y Zr Nb Mo Tc Ru Rh Pd(NO3)2 AgNO3 Cd(NO3)2 In Sn Sb Te I Xe
CsNO3 Ba(NO3)2   Hf Ta W Re Os Ir Pt Au Hg2(NO3)2,
Hg(NO3)2
Tl(NO3)3 Pb(NO3)2 Bi(NO3)3 Po At Rn
Fr Ra   Rf Db Sg Bh Hs Mt Ds Rg Cn Uut Fl Uup Lv Uus Uuo
La Ce(NO3)x Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa UO2(NO3)2 Np Pu Am Cm Bk Cf Es Fm Md No Lr