Silver nitrate
- Nitrate of silver
- Nitrate of silver
- Höllenstein
- Lapis Infernalis
D08AL01
Colorless, transparent, non-hygroscopic, rhombohedral crystals
Fixed
4.35 g · cm -3 ( 19 ° C)
212 ° C
440 ° C (thermal decomposition)
- Slightly soluble in water ( 2160 g · l-1 at 20 ° C)
- Sparingly soluble in ethanol
Risk
0.01 mg · m-3
-124.4 KJ / mol
Template: Infobox chemical / molecular formula search is not possible
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 NO3-.
Production and representation
It is prepared by reaction of silver with nitric acid to form nitrous gases:
Or by the reaction of nitric acid with silver oxide without formation of nitrous gases:
Properties
Silver nitrate, AgNO3, forms colorless, tabular crystals. It is very readily soluble in water and sparingly soluble in ethanol. Silver nitrate has a melting point of 209 ° C, with heating to about 440 ° C. decomposition deposition of metallic silver and discharge of nitrous gases. It must be well closed and protected from light stored ( for example in brown glass bottles), there are already sufficient small amounts of dust to reduce silver nitrate exposure to light to finely divided silver. Very pure silver nitrate, however, is not sensitive to light. Silver nitrate forms with chloride, bromide, iodide and sulfide ions sparingly soluble precipitates.
With bases (eg sodium hydroxide) to form silver (I ) oxide:
Silver nitrate denatured protein by formation of silver salts of the proteins (eg Silberalbuminat ), in solutions of these flakes. In case of skin contact form black spots quickly, because the silver ions are reduced to metal.
Use
- Silver nitrate is a detection reagent for halides ( Cl -, Br -, I - ions) and pseudohalides and is used for the quantitative determination of the titration according to Mohr or Fajans. Fluoride ion (F- ) can not be detected by precipitation as silver (I ) fluoride is highly soluble in water as the only silver.
- Silver nitrate is used for the detection of aldehyde groups and proteins. In the protein biochemistry, silver nitrate is used for staining of proteins that were separated, eg in a polyacrylamide gel. Silver nitrate is in histology to stain tissue sections, for example in the Golgi -Cox method used. In forensics ( fingerprinting ) a silver nitrate -methanol solution for visualization of fingerprints is used.
- Silver nitrate is the starting material for preparation of other silver salts, particularly of the silver halides to be used in photography. It serves for galvanic plating, for the preparation of silver mirrors and as a hair dye.
- Against skin growths, ulcers and warts used: - ( % solutions for the local treatment 0.5 ) as well as the etchant ( " Lapisstift " "hell stone etching pen ", Austria ) In medicine, silver nitrate as an antiseptic and astringent. Until a few years newborn was a one per cent silver nitrate solution dripped into the eyes to prevent eye infection gonorrhoeische ( Crede prophylaxis). Today, instead, an antibiotic is given, which does not make your eyes hurt and is effective against several different pathogens simultaneously. Due to the increasing antibiotic resistance, however, is now considered to return to the use of silver nitrate.
- In biotechnology, silver nitrate can be used as an additive in culture media, for example, callus cultures. The goal is to provide the acting as ethylene antagonist silver ions in the medium. Advantageous here is the high water solubility of the silver nitrate, would otherwise be possible, the use of silver chloride or a similar salt.
- Silver nitrate is used for the preparation of bills to identify thieves or bank robbers, as not washable turns black after touching the skin.
Safety
Silver nitrate is highly irritating to skin and mucous membranes and destroy living tissue in a position ( burns ). As an environmental poison it requires special disposal.