Silver nitrate

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Silver nitrate
Silver-nitrate-2D.svg
Silver nitrate crystals.jpg
Silver-nitrate-xtal-2x2x2-c-3D-bs-17.png
Names
IUPAC name
Silver nitrate
Systematic IUPAC name
Silver(I) nitrate
Other names
Nitric acid silver(1+) salt
Lapis infernalis
Argentous nitrate
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.028.958 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 231-853-9
PubChem CID
RTECS number
  • VW4725000
UNII
UN number 1493
  • InChI=1S/Ag.NO3/c;2-1(3)4/q+1;-1 Yes check.svgY
    Key: SQGYOTSLMSWVJD-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/Ag.NO3/c;2-1(3)4/q+1;-1
    Key: SQGYOTSLMSWVJD-UHFFFAOYAW
  • [N+](=O)([O-])[O-].[Ag+]
Properties
AgNO3
Molar mass 169.872 g·mol−1
Appearancecolorless 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] [2]
Boiling point 440 °C (824 °F; 713 K)
decomposes [1]
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) [3]
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) [2]
Solubility in acetone 0.35 g/100 g (14 °C)
0.44 g/100 g (18 °C) [3]
Solubility in benzene 0.22 g/kg (35 °C)
0.44 g/kg (40.5 °C) [3]
Solubility in ethanol 3.1 g/100 g (19 °C) [3]
Solubility in ethyl acetate 2.7 g/100 g (20 °C) [2]
log P 0.19
45.7·10−6 cm3/mol
1.744
Viscosity 3.77 cP (244 °C)
3.04 cP (275 °C) [2]
Structure
Orthorhombic, oP56 [4]
P212121, No. 19 [4]
222 [4]
a = 6.992(2) Å, b = 7.335(2) Å, c = 10.125(2) Å [4]
α = 90°, β = 90°, γ = 90°
Thermochemistry
93.1 J/mol·K [1]
140.9 J/mol·K [1]
−124.4 kJ/mol [1]
−33.4 kJ/mol [1]
Pharmacology
D08AL01 ( WHO )
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Reacts explosively with ethanol. Toxic. Corrosive.
GHS labelling:
GHS-pictogram-rondflam.svg GHS-pictogram-acid.svg GHS-pictogram-skull.svg GHS-pictogram-pollu.svg [5]
Danger
H272, H314, H410 [5]
P220, P273, P280, P305+P351+P338, P310, P501 [5]
NFPA 704 (fire diamond)
3
0
2
OX
Lethal dose or concentration (LD, LC):
800 mg/kg (rabbit, oral)
20 mg/kg (dog, oral) [6]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)
Crystals of silver nitrate under a microscope. AgNO3 microscope 2.JPG
Crystals of silver nitrate under a microscope.

Silver nitrate is an inorganic compound with chemical formula AgNO
3
. It 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 ancient alchemists who associated silver with the moon. [7] In solid silver nitrate, the silver ions are three-coordinated in a trigonal planar arrangement. [4]

Contents

Synthesis and structure

Albertus Magnus, in the 13th century, documented the ability of nitric acid to separate gold and silver by dissolving the silver. [8] Indeed silver nitrate can be prepared by dissolving silver in nitric acid followed by evaporation of the solution. The stoichiometry of the reaction depends 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

The structure of silver nitrate has been examined by X-ray crystallography several times. In the common orthorhombic form stable at ordinary temperature and pressure, the silver atoms form pairs with Ag---Ag contacts of 3.227 Å. Each Ag+ center is bonded to six oxygen centers of both uni- and bidentate nitrate ligands. The Ag-O distances range from 2.384 to 2.702 Å. [4]

Silver-nitrate-xtal-Ag-coordination-3D-bs-17.png

Reactions

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 fully decomposes at 440 °C. [9]

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

Precursor to other silver compounds

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: [10]

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

Halide abstraction

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+
(aq) + X
(aq) → AgX(s)

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. 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.

The same reaction was used on steamships in order to determine whether or not boiler feedwater had been contaminated with seawater. It is still used to determine if moisture on formerly dry cargo is a result of condensation from humid air, or from seawater leaking through the hull. [11]

Organic synthesis

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] Silver nitrate is highly soluble in water but is poorly soluble in most organic solvents, except acetonitrile (111.8 g/100 g, 25 °C). [13]

Biology

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. [14]

Indelible ink

Silver nitrate produces long-lasting stain when applied to skin. An electoral stain makes use of this to mark a finger of people who have voted in an election, allowing easy identification to prevent double-voting.

Medicine

Micrograph showing a silver nitrate (brown) marked surgical margin. Atypical leiomyoma intermed mag.jpg
Micrograph showing a silver nitrate (brown) marked surgical margin.

Silver salts have antiseptic properties. In 1881 Credé introduced the use of dilute solutions of AgNO3 in newborn babies' eyes at birth to prevent contraction of gonorrhea from the mother, which could cause blindness. (Modern antibiotics are now used instead). [15] [16] [17]

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. [18]

Silver nitrate is used to cauterize superficial blood vessels in the nose to help prevent nose bleeds.

Dentists sometimes use silver nitrate-infused swabs to heal oral ulcers. Silver nitrate is used by some podiatrists to kill cells located in the nail bed.

The Canadian physician C. A. Douglas Ringrose researched the use of silver nitrate for sterilization procedures, believing that silver nitrate could be used to block and corrode the fallopian tubes. [19] The technique was ineffective. [20]

Disinfection

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

Skin stained by silver nitrate Silver nitrate stains.jpg
Skin 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. [21]

Safety

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 toxic and corrosive. [22] 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 has not been thoroughly investigated for potential carcinogenic effect. [23]

Silver nitrate is currently unregulated in water sources by the United States 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 despite the discolouration. [24] 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.

Related Research Articles

Nitric acid is the inorganic compound with the formula HNO3. It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitric acid has a concentration of 68% in water. When the solution contains more than 86% HNO3, it is referred to as fuming nitric acid. Depending on the amount of nitrogen dioxide present, fuming nitric acid is further characterized as red fuming nitric acid at concentrations above 86%, or white fuming nitric acid at concentrations above 95%.

Silver Chemical element, symbol Ag and atomic number 47

Silver is a chemical element with the symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earth's crust in the pure, free elemental form, as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold, lead, and zinc refining.

In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively charged sodium ions and negatively charged chloride ions.

The chloride ion is the anion Cl. It is formed when the element chlorine gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts such as sodium chloride are often very soluble in water. It is an essential electrolyte located in all body fluids responsible for maintaining acid/base balance, transmitting nerve impulses and regulating liquid flow in and out of cells. Less frequently, the word chloride may also form part of the "common" name of chemical compounds in which one or more chlorine atoms are covalently bonded. For example, methyl chloride, with the standard name chloromethane is an organic compound with a covalent C−Cl bond in which the chlorine is not an anion.

Corrosive substance Substance that will damage or destroy other substances by means of a chemical reaction

A corrosive substance is one that will damage or destroy other substances with which it comes into contact by means of a chemical reaction.

Dinitrogen pentoxide Chemical compound

Dinitrogen pentoxide is the chemical compound with the formula N2O5, also known as nitrogen pentoxide or nitric anhydride. It is one of the binary nitrogen oxides, a family of compounds that only contain nitrogen and oxygen. It exists as colourless crystals that melt at 41 °C. Its boiling point is 47 °C, and sublimes slightly above room temperature, yielding a colorless gas.

Silver chloride Chemical compound with the formula AgCl

Silver chloride is a chemical compound with the chemical formula AgCl. This white crystalline solid is well known for its low solubility in water (this behavior being reminiscent of the chlorides of Tl+ and Pb2+). Upon illumination or heating, silver chloride converts to silver (and chlorine), which is signaled by grey to black or purplish coloration to some samples. AgCl occurs naturally as a mineral chlorargyrite.

Barium nitrate Chemical compound

Barium nitrate is the inorganic compound with the chemical formula Ba(NO3)2. It, like most barium salts, is colorless, toxic, and water-soluble. It burns with a green flame and is an oxidizer; the compound is commonly used in pyrotechnics.

Tollens reagent Chemical reagent used to distinguish between aldehydes and ketones

Tollens' reagent is a chemical reagent used to distinguish between aldehydes and ketones along with some alpha-hydroxy ketones which can tautomerize into aldehydes. The reagent consists of a solution of silver nitrate, ammonia and some sodium hydroxide. It was named after its discoverer, the German chemist Bernhard Tollens. A positive test with Tollens' reagent is indicated by the precipitation of elemental silver, often producing a characteristic "silver mirror" on the inner surface of the reaction vessel.

Silver perchlorate Chemical compound

Silver perchlorate is the chemical compound with the formula AgClO4. This white solid forms a monohydrate and is mildly deliquescent. It is a useful source of the Ag+ ion, although the presence of perchlorate presents risks. It is used as a catalyst in organic chemistry.

Uranyl nitrate Chemical compound

Uranyl nitrate is a water-soluble yellow uranium salt with the formula UO2(NO3)2 · n H2O. The hexa-, tri-, and dihydrates are known. The compound is mainly of interest because it is an intermediate in the preparation of nuclear fuels.

A salt metathesis reaction, sometimes called a double displacement reaction, is a chemical process involving the exchange of bonds between two reacting chemical species which results in the creation of products with similar or identical bonding affiliations. This reaction is represented by the general scheme:

Silver oxide Chemical compound

Silver oxide is the chemical compound with the formula Ag2O. It is a fine black or dark brown powder that is used to prepare other silver compounds.

Silver chromate Chemical compound

Silver chromate is an inorganic compound with formula Ag2CrO4 which appears as distinctively coloured brown-red crystals. The compound is insoluble and its precipitation is indicative of the reaction between soluble chromate and silver precursor salts (commonly potassium/sodium chromate with silver nitrate). This reaction is important for two uses in the laboratory: in analytical chemistry it constitutes the basis for the Mohr method of argentometry, whereas in neuroscience it is used in the Golgi method of staining neurons for microscopy.

A Nitrate Test is a chemical test used to determine the presence of nitrate ion in solution. Testing for the presence of nitrate via wet chemistry is generally difficult compared with testing for other anions, as almost all nitrates are soluble in water. In contrast, many common ions give insoluble salts, e.g. halides precipitate with silver, and sulfate precipitate with barium.

Iron(III) nitrate Chemical compound

Iron(III) nitrate, or ferric nitrate, is the name used for a series of inorganic compounds with the formula Fe(NO3)3.(H2O)n. Most common is the nonahydrate Fe(NO3)3.(H2O)9. The hydrates are all pale colored, water-soluble paramagnetic salts.

Bromous acid Chemical compound

Bromous acid is the inorganic compound with the formula of HBrO2. It is an unstable compound, although salts of its conjugate base – bromites – have been isolated. In acidic solution, bromites decompose to bromine.

Compounds of lead exist with lead in two main oxidation states: +2 and +4. The former is more common. Inorganic lead(IV) compounds are typically strong oxidants or exist only in highly acidic solutions.

Thorium(IV) nitrate Chemical compound

Thorium(IV) nitrate is a chemical compound with the formula Th(NO3)4. A white solid in its anhydrous form, it can form tetra- and pentahydrates. As a salt of thorium it is weakly radioactive.

Silver hyponitrite is an ionic compound with formula Ag2N2O2 or (Ag+
)2[ON=NO]2−, containing monovalent silver cations and hyponitrite anions. It is a bright canary yellow solid practically insoluble in water and most organic solvents, including DMF and DMSO.

References

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  3. 1 2 3 4 Seidell, Atherton; Linke, William F. (1919). Solubilities of Inorganic and Organic Compounds (2nd ed.). New York City: D. Van Nostrand Company. pp.  617–619.
  4. 1 2 3 4 5 6 Meyer, P.; Rimsky, A.; Chevalier, R. (1978). "Structure du nitrate d'argent à pression et température ordinaires. Exemple de cristal parfait". Acta Crystallogr. B . 34 (5): 1457–1462. doi:10.1107/S0567740878005907.
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  9. 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): 747–772. Bibcode:1972JPCRD...1..747S. doi:10.1063/1.3253104. S2CID   95532988.
  10. Campaigne, E.; LeSuer, W. M. (1963). "3-Thiophenecarboxylic (Thenoic) Acid". Organic Syntheses .{{cite journal}}: CS1 maint: multiple names: authors list (link); Collective Volume, vol. 4, p. 919 (preparation of Ag2O, used in oxidation of an aldehyde)
  11. "Silver nitrate method". Transport Information Service. Gesamtverband der Deutschen Versicherungswirtschaf. Retrieved 22 June 2015.
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  13. "silver nitrate". chemister.ru. Retrieved 2019-04-04.
  14. 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. S2CID   38335416.
  15. Peter.H (2000). "Dr Carl Credé (1819–1892) and the prevention of ophthalmia neonatorum". Arch Dis Child Fetal Neonatal Ed. 83 (2): F158–F159. doi:10.1136/fn.83.2.F158. PMC   1721147 . PMID   10952715.
  16. Credé C. S. E. (1881). "Die Verhürtung der Augenentzündung der Neugeborenen". Archiv für Gynäkologie. 17 (1): 50–53. doi:10.1007/BF01977793. S2CID   10053605.
  17. Schaller, Ulrich C. & Klauss, Volker (2001). "Is Credés prophylaxis for ophthalmia neonatorum still valid?". Bulletin of the World Health Organization. 79 (3): 262–266. PMC   2566367 . PMID   11285676.
  18. British Library, India Office Records, European Manuscripts, MSS EUR F171/33/3, page 109.
  19. Ringrose CA. (1973). "Office tubal sterilization". Obstetrics and Gynecology. 42 (1): 151–5. PMID   4720201.
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  21. Sterling, J. C.; Handfield-Jones, S.; Hudson, P. M.; British Association of Dermatologists (2001). "Guidelines for the management of cutaneous warts" (PDF). British Journal of Dermatology. 144 (1): 4–11. doi:10.1046/j.1365-2133.2001.04066.x. PMID   11167676. S2CID   20179474. Archived from the original (PDF) on 2012-03-03.
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