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| Mercury(II) oxide | |
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| IUPAC name | Mercury(II) oxide |
| Other names | Mercuric oxide Montroydite |
| Identifiers | |
| CAS number | 21908-53-2 |
| Properties | |
| Molecular formula | HgO |
| Molar mass | 216.5894 g/mol |
| Appearance | Yellow or red solid |
| Density | 11.14 g/cm³, solid |
| Melting point |
500 °C (773.15 K) |
| Boiling point |
N/A |
| Solubility in water | Insoluble |
| Basicity (pKb) | N/A |
| Hazards | |
| EU classification | Toxic (T) |
| R-phrases | R35 |
| S-phrases | (S1/2), S26, S37/39, S45 |
| Flash point | Non-flammable. |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
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Mercury(II) oxide, also called mercuric oxide, has a formula of HgO and a formula weight of 216.6. It has a red or orange color. Mercury(II) oxide is a solid at room temperature and pressure. Mineralogical form called montroydite is very rarely found. This article does not deal with Hg2O, CAS 15829-53-5, also called mercurous oxide.
Contents |
Synthesis
The red form of HgO can be made by heating Hg on oxygen at roughly 350 °C, or by pyrolysis of Hg(NO3)2.1 The yellow form can be obtained by precipitation of aqueous Hg2+ with alkali.1 The difference in colour is due to particle size, both forms have the same structure consisting of near linear O-Hg-O units linked in zigzag chains with an O-Hg-O angle of 108°.1
Uses
HgO is sometimes used in the production of mercury as it decomposes quite easily. When it decomposes, oxygen gas is generated.
It is also used as a material for cathodes for mercury batteries. 2
It is one of the stated possibilities for the alleged substance "red mercury".
History
In 1774, Joseph Priestley discovered the oxygen released by heating mercuric oxide, although he did not identify the gas as oxygen. Rather, Priestly called it "dephlogisticated air", as that was the paradigm that he was working under at the time.3 Lavoisier called "dephlogisticated air" as "oxygen" due to the acidic compounds that the gas produced.4 This is why the textbook account of the discovery of oxygen is inaccurate in the sense that it is really impossible to answer who "discovered" oxygen. This was, however one of the major milestones of chemistry.
Before Priestly, oxygen had been discovered by the Swedish chemist Carl Wilhelm Scheele some time before 1773, by the same method as Priestly. However, Priestly's discovery was published already in 1775 and Scheele's not until 1777,5 which is claimed to be because of a very long delay on the part of the publisher.
References
- ^ a b c Greenwood, Norman N.; Earnshaw, A. (1997), Chemistry of the Elements (2nd ed.), Oxford: Butterworth-Heinemann, ISBN 0-7506-3365-4
- ^ Moore, John W.; Conrad L. Stanitski, Peter C. Jurs (2005). Chemistry: The Molecular Science, Thomson Brooks/Cole. pp. 941. ISBN 0534422012, http://books.google.com/books?id=dOD4dTQ3-ZkC&pg=PA941&dq=Mercury(II)+oxide+anode+%22mercury+battery%22&sig=_TpBlFZylDysGWtKISXMsC1f7n0#PPA941,M1.
- ^ Almqvist, Ebbe (2003). History of Industrial Gases, Springer. pp. 23. ISBN 0306472775, http://books.google.com/books?id=OI0fTJhydh4C&pg=PA23&dq=Joseph+Priestley+oxygen+mercury&sig=vbMx6JVeBjsvg2g29DFXj_Xkoxc.
- ^ Stephen, Leslie (1896). Dictionary of National Biography, Smith, Elder. pp. 373, http://books.google.com/books?id=CiYJAAAAIAAJ&q=Lavoisier+oxygen+dephlogisticated+air&dq=Lavoisier+oxygen+dephlogisticated+air&lr=&pgis=1.
- ^ Oxygen, history
External links
Wikipedia content modification information:
- This page was last modified on 24 November 2008, at 19:51.
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