Mercury (II) oxide

Crystal structure
	__ Hg 2+ __ O 2−
General
Surname	Mercury (II) oxide
other names	Mercury oxide; Mercury dioxide; red precipitate; yellow precipitate; red leu;
Ratio formula	HgO
Brief description	orange-red, odorless solid
External identifiers / databases
EC number	244-654-7
ECHA InfoCard	100.040.580
PubChem	30856
Wikidata	Q174727
properties
Molar mass	216.59 g mol −1
Physical state	firmly
density	11.1 g cm −3 (20 ° C)
Melting point	> 400 ° C (decomposition)
Vapor pressure	0.12 Pa (20 ° C)
solubility	practically insoluble in water (0.052 g l −1 at 25 ° C)
safety instructions
H and P phrases	H: 300 + 310 + 330-373-410
	P: 273-280-302 + 352-304 + 340-308 + 310
MAK	0.1 mg m −3
Toxicological data	18 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) oxide is a chemical compound from the group of oxides .

Occurrence

Mercury (II) oxide occurs naturally as the very rare mineral montroydite .

Extraction and presentation

Mercury (II) oxide

The red form of mercury (II) oxide can be obtained by reacting mercury with oxygen at over 350 ° C or by pyrolysis of mercury (II) nitrate , the yellow form by the precipitation of dissolved Hg ²⁺ with alkalis. The different color is only the result of the different particle sizes, as both shapes have the same structure with chains of linear O-Hg-O units and angled (108 °) Hg-O-Hg units.

Its trigonal modification can be obtained by reacting potassium tetraiodomercurate (II) with sodium or potassium hydroxide solution at 50 ° C.

{\ displaystyle \ mathrm {K_ {2} HgI_ {4} +2 \ KOH \ longrightarrow HgO + 4 \ KI + H_ {2} O}}

properties

Mercury (II) oxide is a light-sensitive orange-red solid that is poorly soluble in water . Like mercury itself, the oxide is very toxic. If you heat mercury oxide, it turns almost black from 400 ° C and then breaks down into oxygen and mercury from 500 ° C :

{\ displaystyle \ mathrm {2 \ HgO \ rightarrow 2 \ Hg + O_ {2}}}

The connection comes in two modifications. The trigonal modification has a crystal structure with the space group P 3 ₁ 21 (space group no. 152) and the lattice parameters a = 357.7 pm and c = 868.1 pm. Above 200 ° C this changes into the orthorhombic modification, which has the space group Pnma (No. 62) and the lattice parameters a = 661.2 pm, b = 552.0 pm and c = 352.1 pm. Template: room group / 152Template: room group / 62

use

Mercury (II) oxide can be used to produce pure mercury. As early as 1774 Joseph Priestley discovered that heated mercury (II) oxide releases oxygen and forms mercury, although he did not recognize the resulting gas as oxygen. It was used as a cathode material until mercury-zinc batteries were banned . Oxygen can be produced particularly well with mercury (II) oxide in targeted quantities on a laboratory scale. The weighing of the required amount is quite precise due to the high density of mercury. In addition, the mercury (II) oxide crystals do not carry any water of crystallization with them.

poisoning

Symptoms

When inhaled, a cough occurs. The substance can be absorbed through the intact skin. It causes reddening on the skin itself. Oral ingestion leads to diarrhea and abdominal pain. In principle, the substance irritates the respiratory tract, eyes and skin. Repeated or chronic contact with mercury oxide can cause sensitization. Kidney damage can also develop.

Emergency response

The patient must be rescued from the contaminated environment using self-contained breathing apparatus. Remove contaminated clothing and flush the affected skin with plenty of water. Each patient receives at least four liters of oxygen per minute. If the eye is affected, it must be anesthetized and carefully rinsed. In the case of oral intake, the patient receives 1 gram of medicinal charcoal per kilogram of body weight. In any case, clinical monitoring must be carried out. In the clinic, dimercaptopropane sulfonic acid can be used as a specific antidote .

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g Data sheet mercury (II) oxide (PDF) from Merck , accessed on January 19, 2011.
↑ ^a ^b Entry on mercury (II) oxide in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling falls under the group entry inorganic compounds of mercury with the exception of mercuric sulphide and those specified elsewhere in this Annex in the Classification and Labeling Inventory of European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
^ Mineral Atlas: Montroydite
↑ ^a ^b Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 1053.

[Merck-SDB-1] ↑ ^a ^b ^c ^d ^e ^f ^g Data sheet mercury (II) oxide (PDF) from Merck , accessed on January 19, 2011.

[GESTIS-2] Entry on mercury (II) oxide in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .

[CLP_100.240.785-3] Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling falls under the group entry inorganic compounds of mercury with the exception of mercuric sulphide and those specified elsewhere in this Annex in the Classification and Labeling Inventory of European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[4] Mineral Atlas: Montroydite

[brauer-5] Georg Brauer (Ed.), With the collaboration of Marianne Baudler u a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , p. 1053.