ENG:

What is red mercury?

David Adam
Thursday September 30, 2004
The Guardian

The only thing we can be sure of is that it’s a ripping yarn. Rumours that Soviet nuclear experts had produced a mysterious explosive material with unimaginable destructive power first circulated in the 1970s, and despite several official investigations and subsequent denials the story refuses to die. The near-mythical compound cropped up again on Sunday, when the News of the World claimed it had foiled a terrorist plot to buy red mercury as material for a dirty bomb. Depending on who you believe, red mercury is either an elaborate hoax, a codename for nuclear material smuggled through the former iron curtain, or a terrifying new trigger for a handheld hydrogen bomb. What it isn’t, according to the speculation and hearsay that makes up the scientific literature on the subject, is any use for a dirty bomb (one that scatters radioactive material).

“Nobody would dream of getting that stuff for a dirty bomb,” says Frank Barnaby, a nuclear physicist who worked at the Atomic Weapons Establishment at Aldermaston in the 1950s. “For a terrorist it would offer no significant advantages over an ordinary high explosive or, if they wanted a dirty bomb, a radioactive source. To go to the trouble of spending huge amounts of money on red mercury makes no sense at all.”

Particularly so if all you get for the News of the World’s reported price of £300,000 a kilo is mercury dyed red with nail varnish, which, according to a 1994 investigation by the Russian prosecutor-general’s office, is what was in the “red mercury” sold by Russian conmen throughout Europe and the Middle East after the collapse of the Soviet Union.

Others, including Sam Cohen, the inventor of the neutron bomb, disagree, and Barnaby says there is evidence that the Soviets churned out vast quantities of mercury antimony oxide, the intermediate – and equally elusive - compound from which red mercury is supposedly produced by placing it inside a nuclear reactor. “There’s no doubt that they made a large amount of that stuff. I’ve talked to chemists who have analysed it in East Germany,” he says. “But what they did with it is a mystery.”

Some say the intermediate compound can multiply the yield of explosions and that it was used inside conventional Soviet nuclear weapons or as a rocket fuel additive. Others say the compound was irradi ated in the core of nuclear reactors to produce pure red mercury, capable of exploding with enough heat and pressure to act as a trigger inside a briefcase-sized fusion bomb.

The International Atomic Energy Authority in Vienna takes a different view. “Red mercury doesn’t exist,” a spokesman says. “The whole thing is a bunch of malarkey.”

sau la anumite temperaturi:
        -Aluminiu
        -Paladiu

Formarea lor are loc cu degajare de caldura, mai ales a celor cu metalele
alcaline. In numeroase cazuri, in cadrul unui sistem M-Hg rezulta o suita de
compusi intermetalici.
  Ex:
  --
In cazul amalgamului de Na, au fost identificati compusii :
        NaHg6, NaHg4, Na3Hg2
        NaHg, Na5Hg2, Na3Hg
        Na7Hg8, NaHg2;
Amalgamele cu continut mic de metal strain sunt lichide, air cele cu
continut mare sunt solide, uneori cristalizate. Prin incalzire, amalgamele se
descompun in elemente, iar cele ale metalelor alcaline sau cu Al sunt usor
alterabile in aer sau in apa.
        Depuse pe suprafata metalelor rezistente fata de agenti chimici,
acestea devin active. Al descompune apa la rece cu degajare de O2, explicatia
fiind datorata faptului ca amalgamele indeparteaza pelicula protectoare si
aderenta de oxid.
        Amalgamele de Plutoniu sunt piroforice.

                              500øC
                        2HgO  ------> 2Hg + O2

Halogenuri de Hg
~~~~~~~~~~~~~~~~
        Halogenurile de Hg (II) au carecter de combinatii covalente si nu
ionizeaza, desi sunt relativ solubile.
        Diclorura, HgCl2 - substanta de culoare alba, toxica, care sublimeaza
fara descompunere, este solubila in apa rece si are mare tendinta de a
hidroliza, trecind in saruri bazice.

                HgCl2  + H OH  <----->  Hg(OH)Cl + HCl

Sulfati de Hg
~~~~~~~~~~~~~
        Prisme ortorombice, HgSO4 - anhidru, prisme de culoare alba care
devin negre la actiunea luminii, iar cu apa hidrolizeaza separind sulfatul bazic

                                HgSO4 ù 2HgO;

Hg2SO4 - pulbare cristalina, de culoare alba, greu solubile in apa.

Carbonati de Hg
~~~~~~~~~~~~~~~
        Hg4O3CO3 -  se prezinta sub forma de sare bazica, de culoare
rosu-brun, este un compus de mercur (II).
        Hg2CO3 - pulbere cristalina, alba, greu solubila in apa.

Halogenuri de tip Hg2X2
~~~~~~~~~~~~~~~~~~~~~~~
        Sunt cristale cu retele tetragonale, ce contin molecule catenare

                                X - Hg - Hg - X

diamagnetice, greu solubile in apa, cu exceptia florurii, care se descompune
hidrolitic in HgO si Hg.
        La incalzire, clorura (calomelul) prezinta termosensibilitate
cromatica reversibila, astfel ca la incalzire schimba culoarea din alb in
galben si verde dupa racire.
        Iodura trece din galben treptat in portocaliu, apoi in rosu inchis,
dupa care se topeste sub forma unui lichid negru, fenomenul fiind reversibil.
Prezinta o puternica birefringenta.

Azotat de Hg
~~~~~~~~~~~~
        Hg2(NO3)2ù2H2O - cristale incolore, usor solubile in apa rece, care
hidrolizeaza la cald separind Hg2(OH)NO3.

                        HgS + Fe  -----> Hg + FeS

Se obtine si din oxidul de Hg, in mod asemanator dar fara nici un alt metal,
iar temperatura este mai scazuta ÷500øC.
        In stare nativa se gaseste mai rar.

Utilizare:
Pe linga utilizarile in instalatiile electrochimice de laborator  (polarografia ) si in termometre, se foloseste pe scara larga in industria  chimica la fabricarea NaOH in electrizoare cu catod de mercur, iar in idustria  extractiva la separarea aurului si argintului prin amalgamare.
Amalgamele de Na se folosesc ca agenti reducatori in chimie, iar cele  de zinc si alte metale pentru plombe in stomatologie.
De asemenea joaca rolul de agent termic in reactoarele nucleare.  Sarurile sale se utilizeaza in farmacie, iar “fulminatul de mercur” la  detonarea explozivilor. Mai este folosit in pompele de difuzie cu mercur, care  permit obtinerea unui vid inaintat de ordinul a 10e-10 torr, in lampile de  iluminat etc.

ENG: Mercury
__________

Mercury is the only common metal liquid at ordinary temperatures. Mercury is sometimes called quicksilver. It rarely occurs free in nature and is found mainly in cinnabar ore (HgS) in Spain and Italy. It is a heavy, silvery-white liquid metal. It is a rather poor conductor of heat as compared with other metals but is a fair conductor of electricity. It alloys easily with many metals, such as gold, silver, and tin. These alloys are called amalgams. Its ease in amalgamating with gold is made use of in the recovery of gold from its ores.

The most important salts are mercuric chloride HgC1₂ (corrosive sublimate – a violent poison), mercurous chloride Hg₂Cl₂ (calomel, occasionally still used in medicine), mercury fulminate (Hg(ONC)₂, a detonator used in explosives), and mercuric sulphide (HgS, vermillion, a high-grade paint pigment).

Organic mercury compounds are important – and dangerous. Methyl mercury is a lethal pollutant found in rivers and lakes. The main source of pollution is industrial wastes settling to the river and lake bottoms.

As mercury is a very volatile element, dangerous levels are readily attained in air. Mercury vapour should not exceed 0.1 mg m^-3 in air. Air saturated with the vapour at 20°C contains mercury in a concentration far greater than that limit. The danger increases at higher temperatures. It is therefore important that mercury be handled with care. Containers of mercury should be securely covered and spillage should be avoided. Mercury should only be handled under in a well-ventilated area. If you are in possession of any mercury you are advised to contact a properly qualified chemist or public health laboratory for its safe disposal.

Small amounts of mercury spillage can be cleaned up by addition of sulphur powder. The resulting mixture should be disposed of carefully.

The physical appearance of mercury is well known because of its use in many thermometers. It was common to demonstrate the formation of mercury in the laboratory by heating mercury sulphide (cinnabar, HgS) but this is strongly discouraged today because of the toxicity of mercury vapours. Don’t do it! However, this method forms the basis of commercial extraction. The prepared cinnabar ore is heated in a current of air and the mercury vapour condensed.

HgS + O₂ (600°C) → Hg (l) + SO₂ (g)

The crude mercury is then washed with nitric acid and treated with air in order to remove impurities as oxides or into solution. Further purification is achieved by distillation at reduced pressure.