Mercury HG
Mercury is the only metal that is liquid at standard temperature and pressure conditions.
| Properties | ||
| Phase Liquid density at m.p Melting Point Boiiling point Critical point Heat of fusion Heat of vaporisation Molar heat capacity | liquid 13.534 g.cm?3 234.32 K, -38.83 °C, -37.89 °F 629.88 K, 356.73 °C, 674.11 °F 1750 K, 172.00 MPa 2.29 kJ.mol?1 59.11 kJ.mol?1 27.983 J.mol? 1.K1 | |
Where it comes from
Mercury occurs in deposits throughout the world mostly as cinnabar (mercuric sulphide). The red pigment vermilion is mostly obtained by reduction from cinnabar. Cinnabar is highly toxic trough the ingestion or inhalation of the dust.
Mercury is used in thermometers, barometers, manometers, sphygmomanometers, float valves, some electrical switches, and other scientific apparatus, although concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favour of alcohol-filled, digital, or thermistor-based instruments.
It remains in use in scientific research applications and in amalgam material for dental work. It is used in lighting: electricity passed through mercury vapour in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light.
Impact on people and the environment
Mercury and most of its compounds are extremely toxic and are generally handled with care; in cases of spills involving mercury (such as from certain thermometers or fluorescent light bulbs) specific cleaning procedures are used to avoid toxic exposure.[87] Essentially, it is recommended to physically merge smaller droplets on hard surfaces, combining them into a single larger pool for easier removal by using an eyedropper, or by pushing it into a disposable container which must then be dealt with according to local regulations.
Mercury poisoning can also result from exposure to water soluble forms of mercury (such as mercuric chloride or methylmercury), inhalation of mercury vapour, or eating seafood contaminated with mercury.