# Silver nitrate

Structural formula
General
Surname Silver nitrate
other names
• Nitric acid silver
• Silver nitrate
• Hellstone
• Lapis Infernalis
• Silver (I) nitrate
• SILVER NITRATE ( INCI )
Molecular formula AgNO 3
Brief description

colorless, transparent, non-hygroscopic, rhombohedral crystals

External identifiers / databases
 CAS number 7761-88-8 EC number 231-853-9 ECHA InfoCard 100,028,958 PubChem 24470 Wikidata Q207442
Drug information
ATC code
properties
Molar mass 169.87 g mol −1
Physical state

firmly

density

4.35 g cm −3 (19 ° C)

Melting point

212 ° C

boiling point

440 ° C (thermal decomposition)

solubility
• Easily soluble in water (2160 g l −1 at 20 ° C)
• easily soluble in DMSO (1300 g l −1 at 25 ° C)
• poorly soluble in ethanol
safety instructions
Please note the exemption from the labeling requirement for drugs, medical devices, cosmetics, food and animal feed
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary

danger

H and P phrases H: 272-290-314-410
P: 210-220-260-280-305 + 351 + 338-370 + 378-308 + 310
MAK

0.01 mg m −3

Thermodynamic properties
ΔH f 0

−124.4 kJ / mol

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Silver nitrate ( trivial : hell stone , Latin Lapis infernalis , hellish stone ) is a salt of nitric acid . It is composed of the cation Ag + and the nitrate anion NO 3 - .

## Extraction and presentation

They are prepared by reaction of silver with nitric acid to form nitrous gases :

${\ displaystyle \ mathrm {3 \ Ag + 4 \ HNO_ {3} (conc.) \ rightarrow \ 3 \ AgNO_ {3} +2 \ H_ {2} O + NO}}$

or through the reaction of nitric acid with silver oxide without the formation of nitrous gases:

${\ displaystyle \ mathrm {Ag_ {2} O + 2 \ HNO_ {3} \ rightarrow \ 2 \ AgNO_ {3} + H_ {2} O}}$

## properties

Silver nitrate, already easily decomposed by light
Hand soiled with AgNO 3

Silver nitrate, AgNO 3 , forms colorless, tabular crystals. It is very easily soluble in water and sparingly soluble in ethanol . Silver nitrate has a melting point of 209 ° C; when heated to around 440 ° C, it decomposes with the separation of metallic silver and the release of nitrous gases. It must be well sealed and protected from light (for example, in brown glass bottles) stored, since even small amounts of dust sufficient silver nitrate exposure to light to be finely divided silver reduce . In contrast, very pure silver nitrate is not sensitive to light. Silver nitrate forms sparingly soluble precipitates with chloride , bromide , iodide and sulfide ions .

${\ displaystyle \ mathrm {Ag ^ {+} {(aq)} + NO_ {3} ^ {-} {(aq)} + X ^ {-} {(aq)} \ rightarrow}}$ ${\ displaystyle \ mathrm {AgX {(s)} + NO_ {3} ^ {-} {(aq)} \, \ X = Cl, Br, I}}$
If you add silver nitrate solution to an aqueous halide solution, solid white or yellow silver halide precipitates, nitrate remains in solution.

With bases (e.g. sodium hydroxide ) silver (I) oxide is formed :

${\ displaystyle \ mathrm {2 \ AgNO_ {3} +2 \ NaOH \ rightarrow Ag_ {2} O + 2 \ NaNO_ {3} + H_ {2} O}}$

Silver nitrate denatures protein by forming silver salts of the proteins (e.g. silver albuminate ), in solutions these flocculate. Black spots quickly form on contact with the skin, as the silver ions are reduced to the metal. The stains can be removed with potassium iodide solution and then washed out with a solution of sodium thiosulphate (fixing salt).

## use

• Silver nitrate is a detection reagent for halides (Cl - , Br - , I - ions) and pseudohalides and is used for their quantitative determination in the Mohr or Fajans titration . Fluoride ions (F - ) can not be detected by precipitation , since silver (I) fluoride is the only silver halide that is readily soluble in water.
• Silver nitrate is used to detect aldehyde groups and proteins . In protein biochemistry , silver nitrate is used in the course of silver staining to stain proteins that z. B. were separated in a polyacrylamide gel . In histology , silver nitrate is used to stain tissue sections, for example in the Golgi- Cox method. In forensic science ( dactyloscopy ), a silver nitrate-methanol solution is used to make fingerprints visible.
• Silver nitrate is the starting material for the representation of other silver salts, especially the silver halides, which are used in analog photography . It is used for galvanic silver plating, for the production of silver mirrors and as a hair dye.
• In medicine , silver nitrate is used as an antiseptic and astringent (0.5% solution for local treatment) and as an etching agent ("Höllenstein-Ätzstift", Austria: "Lapis pen") against skin growths, ulcers and warts . Up until a few years ago, a one percent silver nitrate solution was put into the eyes of newborn babies to prevent gonorrhoeic eye infections ( Credé prophylaxis ); today it has been replaced by less toxic substances.
• In biotechnology, silver nitrate can be used as an additive in culture media, for example for callus cultures . The aim here is as ethylene - antagonist provide silver ions in the medium. The advantage here is the good water solubility of the silver nitrate, otherwise the use of silver chloride or a similar salt would also be possible .
• In the complex analysis of triglycerides , silver nitrate is used to separate the triglycerides in the context of argentation chromatography .
• Silver nitrate is used to prepare banknotes to identify thieves or bank robbers, as the skin turns black after being touched and cannot be washed off.

## safety instructions

Silver nitrate has a strong irritant effect on the skin and mucous membranes and is able to destroy living tissue ( corrosion ). As an environmental toxin , it requires special disposal.

## Individual evidence

1. Entry on SILVER NITRATE in the CosIng database of the EU Commission, accessed on March 11, 2020.
2. a b c Entry on silver nitrate. In: Römpp Online . Georg Thieme Verlag, accessed on October 14, 2014.
3. Entry on silver nitrate in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
4. Dimethyl Sulfoxide (DMSO) Solubility Data. Gaylord Chemical Company, LLC; Bulletin 102, June 2014, p. 15. (PDF)
5. Entry on silver nitrate in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
6. David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-4.
7. E. Campaigne, WM LeSuer: 3-thiophenecarboxylic (Thenoic) Acid In: Organic Syntheses . 33, 1953, p. 94, doi : 10.15227 / orgsyn.033.0094 ; Coll. Vol. 4, 1963, p. 919 ( PDF ).
8. Axel Kramer: Clinical Antiseptics. Springer-Verlag, 2013, ISBN 978-3-642-77715-8 , p. 253 ( limited preview in the Google book search).
9. EM Beyer: Potent inhibitor of ethylene action in plants. In: Plant Physiology . 1976, 58, 3, pp. 268-271.
10. K. Kemper, H.-U. Melchert, K. Rubach, H. Hoffmeister: Characterization of the triglyceride pattern of vegetable and animal fats as well as human and animal sera by means of HPLC after pre-separation on AgNO 3 -impregnated silica gel mini-columns . In: Fresenius' Journal of Analytical Chemistry. Volume 331, No. 6, 1988, pp. 634-641, doi : 10.1007 / BF01032542 .
11. ^ Carola Gessner: Black fingers through marked money. ( Memento of the original from July 9, 2009 in the Internet Archive ) Info: The  archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Süddeutsche Zeitung (from August 26, 2007)