Mercury (II) thiocyanate

Structural formula
General
Surname	Mercury (II) thiocyanate
other names	Mercury thiocyanate; Mercury rhodanide;
Molecular formula	Hg (SCN) 2
Brief description	white, odorless, flammable solid
External identifiers / databases
EC number	209-773-0
ECHA InfoCard	100,008,886
PubChem	11615
Wikidata	Q416035
properties
Molar mass	316.762 g mol −1
Physical state	firmly
density	3.71 g cm −3
Melting point	165 ° C (decomposition)
solubility	poor in water (0.7 g l −1 at 25 ° C); soluble in sodium chloride solution, hydrochloric acid and nitric acid;
safety instructions
H and P phrases	H: 330-310-300-373-410
	EUH: 032
	P: 260-262-280-301 + 310 + 330-331-302 + 352-310-304 + 340 + 310
MAK	0.1 mg m −3
Toxicological data	46 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Mercury (II) thiocyanate (obsolete mercury thiocyanate ) is an inorganic chemical compound of mercury from the group of thiocyanates , the salts of thiocyanic acid ( thiocyanic acid).

Extraction and presentation

Mercury (II) thiocyanate can be produced by the reaction of ammonium thiocyanate with mercury chloride.

It can also be obtained by reacting mercury (II) nitrate with potassium thiocyanate .

{\ displaystyle \ mathrm {Hg (NO_ {3}) _ {2} + \ 2 \ KSCN \ longrightarrow Hg (SCN) _ {2} \ downarrow + \ 2 \ KNO_ {3}}}

properties

Mercury (II) thiocyanate is a white, odorless, flammable solid that is poorly soluble in water. It is obtained in the form of colorless, radiant needles or pearlescent leaves. It is soluble in alcohol and in an excess of a thiocyanate solution with complex formation (e.g .: in ammonium thiocyanate with formation of ammonium tetrathiocyanatomic curate (II) (NH ₄ ) ₂ [Hg (SCN) ₄ ]), but not very soluble in ether. When heated to 165 ° C, decomposition occurs with puffing. Mercury (II) thiocyanate has a monoclinic crystal structure (a = 10.88 Å , b = 4.050 Å, c = 6.446 Å, β = 95.35 °).

use

Mercury (II) thiocyanate is used:

as a detection reagent for chloride ions (color reaction with iron (III) nitrate to mercury (II) chloride and iron (III) thiocyanate ).
as detection reagent for zinc ions: Zn ²⁺ + Hg (SCN) ₄^2- → Zn [Hg (SCN) ₄ ] ↓
in analog photography in developing for enhancing negatives
In the past it was also used as a joke article ( pharaohs snakes ) (forms black, elongated foamy structures when lit), but this is prohibited today due to the toxicity of the mercury vapors.

Individual evidence

↑ Data sheet mercury (II) thiocyanate (PDF) from Merck , accessed on January 18, 2011.

↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on mercury (II) thiocyanate in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .

↑ ^a ^b ^c Entry on mercury (II) thiocyanate. In: Römpp Online . Georg Thieme Verlag, accessed November 30, 2015.

↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entries on organic compounds of mercury with the exception of those specified elsewhere in this Annex and metal salts of thiocyanic acid, with the exception of those specified elsewhere in this Annex in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on March 18, 2017. Manufacturers or distributors can expand the harmonized classification and labeling .

↑ ^a ^b Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 1064.

↑ Report on drinking water tests by the Westphalian Wilhelms University of Münster ( Memento from December 17, 2010 in the Internet Archive ) (PDF; 87 kB)

^ FH Frimmel: Jander / Blasius (founder), textbook of analytical and preparative inorganic chemistry. 14th revised edition by Joachim Strähle and Eberhard Schweda. S. Hirzel Verlag, Stuttgart, 1995, ISBN 3-7776-0612-X , 704 pp., 1 color poster “Separation of the cations”, 1 booklet “First Aid in Acute Emergencies”, hardcover, DM 68.00 . In: Acta hydrochimica et hydrobiologica . tape 24 , no. 2 , January 1, 1996, p. 108-108 , doi : 10.1002 / aheh.19960240216 .

[Merck-1] Data sheet mercury (II) thiocyanate (PDF) from Merck , accessed on January 18, 2011.

[GESTIS-2] ↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on mercury (II) thiocyanate in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .

[Roempp-3] Entry on mercury (II) thiocyanate. In: Römpp Online . Georg Thieme Verlag, accessed November 30, 2015.