Potassium tetraiodomercurate(II)

Potassium tetraiodomercurate(II)
Names
	IUPAC name potassium tetraiodidomercurate(II)
	Other names potassium mercuric iodide, ; Nessler's reagent (principal component)
Identifiers
CAS Number	7783-33-7 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:51568 ;
ChemSpider	22948 ;
ECHA InfoCard	100.029.082
EC Number	231-990-4;
PubChem CID	15980736;
UNII	7N83S6IU0F ;
UN number	3287
CompTox Dashboard (EPA)	DTXSID30893684 ;
	InChI InChI=1S/Hg.4HI.2K/h;41H;;/q+2;;;;;2+1/p-4 Key: OPCMAZHMYZRPID-UHFFFAOYSA-J ;
	SMILES [K+].[K+].I[Hg-2](I)(I)I;
Properties
Chemical formula	K2[HgI4]
Molar mass	786.406 g·mol−1
Appearance	yellow crystals
Odor	odorless
Density	4.29 g/cm3
Solubility in water	very soluble
Solubility	soluble in alcohol, ether, acetone
Hazards
Safety data sheet (SDS)	External MSDS for Nessler's reagent
Related compounds
Other anions	Mercury(II) iodide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Potassium tetraiodomercurate(II) is an inorganic compound with the chemical formula K₂[Hg I₄]. It consists of potassium cations and tetraiodomercurate(II) anions. It is the active agent in Nessler's reagent, used for detection of ammonia.^[2]

Preparation

The compound crystallizes from a heated solution of mercuric iodide, potassium iodide, and precisely 2% water in acetone. Attempted synthesis in concentrated aqueous solution will give the pale orange monohydrate K[Hg(H₂O)I₃] instead.^[3]

Applications

K₂[HgI₄] is a precursor to analogous copper and silver salts M₂[HgI₄] (M=Cu, Ag).^[4]

Nessler's reagent

Nessler's reagent, named after Julius Neßler (Nessler), is a 0.09 mol/L solution of potassium tetraiodomercurate(II) in 2.5 mol/L potassium hydroxide. This pale solution becomes deeper yellow in the presence of ammonia (NH₃). At higher concentrations, a brown precipitate derivative of Millon's base (HgO·Hg(NH₂)Cl) may form. The sensitivity as a spot test is about 0.3 μg NH₃ in 2 μL.^[5]

NH+4 + 2 [HgI₄]²⁻ + 4 OH⁻ → HgO·Hg(NH₂)I↓ + 7 I⁻ + 3 H₂O

The brown precipitate is not fully characterized and may vary from HgO·Hg(NH₂)I to 3HgO·Hg(NH₃)₂I₂.^[6]

References

^ Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. p. 4-82. ISBN 978-1-4200-9084-0.
^ Vogel, Arthur I.; Svehla, G. (1979), Vogel's Textbook of Macro and Semimicro Qualitative Inorganic Analysis (5th ed.), London: Longman, ISBN 0-582-44367-9 – via the Internet Archive
^ Wagenknecht, F.; Juza, R. (1963). "Potassium Triiodomercurate(II)". In Brauer, G. (ed.). Handbook of Preparative Inorganic Chemistry. Vol. 1 (2nd ed.). Academic Press. p. 1100 – via the Internet Archive.
^ Wagenknecht, F.; Juza, R. (1963). "Copper(I) Tetraiodomercurate(II)". In Brauer, G. (ed.). Handbook of Preparative Inorganic Chemistry. Vol. 1 (2nd ed.). Academic Press. p. 1100 – via the Internet Archive.
^ Vogel, Arthur I. (1954), A Textbook of Macro and Semimicro Qualitative Inorganic Analysis (4th ed.), London: Longman, p. 319, ISBN 0-582-44367-9 {{citation}}: ISBN / Date incompatibility (help)
^ Vogel, Arthur I.; Svehla, G. (1979), Vogel's Textbook of Macro and Semimicro Qualitative Inorganic Analysis (5th ed.), London: Longman, pp. 293–294, ISBN 0-582-44367-9 – via the Internet Archive

External links

[crc-1] Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. p. 4-82. ISBN 978-1-4200-9084-0.

[2] Vogel, Arthur I.; Svehla, G. (1979), Vogel's Textbook of Macro and Semimicro Qualitative Inorganic Analysis (5th ed.), London: Longman, ISBN 0-582-44367-9 – via the Internet Archive

[3] Wagenknecht, F.; Juza, R. (1963). "Potassium Triiodomercurate(II)". In Brauer, G. (ed.). Handbook of Preparative Inorganic Chemistry. Vol. 1 (2nd ed.). Academic Press. p. 1100 – via the Internet Archive.

[4] Wagenknecht, F.; Juza, R. (1963). "Copper(I) Tetraiodomercurate(II)". In Brauer, G. (ed.). Handbook of Preparative Inorganic Chemistry. Vol. 1 (2nd ed.). Academic Press. p. 1100 – via the Internet Archive.

[Vogel4th-319-5] Vogel, Arthur I. (1954), A Textbook of Macro and Semimicro Qualitative Inorganic Analysis (4th ed.), London: Longman, p. 319, ISBN 0-582-44367-9 {{citation}}: ISBN / Date incompatibility (help)

[6] Vogel, Arthur I.; Svehla, G. (1979), Vogel's Textbook of Macro and Semimicro Qualitative Inorganic Analysis (5th ed.), London: Longman, pp. 293–294, ISBN 0-582-44367-9 – via the Internet Archive

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v t e Potassium compounds
H, (pseudo)halogens	KF KHF₂ KH KCl KClO KClO₃ KClO₄ KBr KBrO₃ KI KIO₃ KIO₄ KAt KCN KCNO KOCN KSCN
chalcogens	K₂O KOH K₂O₂ KO₂ KO₃ K₂S KHS K₂SO₃ KHSO₃ K₂SO₄ KHSO₄ KHSO₅ K₂S₂O₃ K₂S₂O₅ K₂S₂O₇ K₂S₂O₈ K₂Se K₂SeO₃ K₂SeO₄ K₂Te K₂TeO₃ K₂TeO₄ K₂Po
pnictogens	K₃N KNH₂ KN₃ KNO₂ KNO₃ K₃P KH₂PO₃ K₃PO₄ K₂HPO₄ KH₂PO₄ KPF₆ KAsO₂ K₃AsO₄ K₂HAsO₄ KH₂AsO₄
B, C group	B₄K₂O₇ K₂CO₃ KHCO₃ K₂SiO₃ K₂SiF₆ K₂Al₂O₄ K₂Al₂B₂O₇
transition metals	K₂PtCl₄ K₂Pt(CN)₄ K₂TiF₆ K₂PtCl₆ K₂ReCl₆ K ₂ReF ₆ KAsF₆ K₂ReBr₆ K ₂ReI ₆ K₂ZrF₆ K₄Fe(CN)₆ K₃Fe(CN)₆ K₃Fe(C₂O₄)₃ K₂FeO₄ K₂MnO₄ KMnO₄ K₃CrO₄ K₂CrO₄ K₃CrO₈ KCrO₃Cl K₂Cr₂O₇ K₂Cr₃O₁₀ K₂Cr₄O₁₃ K₄Mo₂Cl₈
organic	KHCO₂ KCH₃CO₂ KCF₃CO₂ K₂C₂O₄ KHC₂O₄ KC₁₂H₂₃O₂ KC₁₈H₃₅O₂ CF₃KO₃S C₃H₂K₂O₄ C₄H₆KO₄ C₅H₇KO₄

Potassium tetraiodomercurate(II)

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Names


IUPAC name potassium tetraiodidomercurate(II)
Other names potassium mercuric iodide, Nessler's reagent (principal component)
Identifiers
CAS Number	7783-33-7^Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:51568^N
ChemSpider	22948^N
ECHA InfoCard	100.029.082
EC Number	231-990-4
PubChem CID	15980736
UNII	7N83S6IU0F^Y
UN number	3287
CompTox Dashboard (EPA)	DTXSID30893684
InChI InChI=1S/Hg.4HI.2K/h;41H;;/q+2;;;;;2+1/p-4^N Key: OPCMAZHMYZRPID-UHFFFAOYSA-J^N
SMILES [K+].[K+].I[Hg-2](I)(I)I
Properties
Chemical formula	K₂[HgI₄]^[1]
Molar mass	786.406 g·mol⁻¹
Appearance	yellow crystals
Odor	odorless
Density	4.29 g/cm³
Solubility in water	very soluble
Solubility	soluble in alcohol, ether, acetone
Hazards
Safety data sheet (SDS)	External MSDS for Nessler's reagent
Related compounds
Other anions	Mercury(II) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is ^YN ?) Infobox references