مرڪري (پارو)

پارو (Mercury؛ سائنسي نالو: Hydrargrum) هڪ ڪيميائي تت آهي. هن جو نشان "Hg" ۽ ايٽمي نمبر "80" آهي. ان کي عام طور تي "مايع چاندي" (quick silver) جي نالي سان سڃاتو وڃي ٿو. اهو هڪ ڳرو، سلور ڪلر  جو، ڊي-بلاڪ جو تت آهي. پارو واحد ڌاتي تت آهي جيڪو معياري گرميء پد ۽ دٻاءُ تي مائع حالت ۾ ھوندو آھي، ٻيو واحد تت جيڪو انهن حالتن ۾ مائع ھوندو آهي، اهو برومين (Bromine) آهي. جيتوڻيڪ سيزيم، گيليم ۽ روبيڊيم جهڙيون ڌاتو ڪمري جي حرارت کان ٿورو مٿي پگهري وڃن ٿيون.  

پارو سڄي دنيا ۾ گهڻو ڪري سينابار (cinnabar)، مرڪيورڪ سلفائيڊ، جي طور تي ملي ٿو. ڳاڙهي رنگ جو ورميلين قدرتي سينابار يا مصنوعي مرڪيورڪ سلفائيڊ کي پيسڻ سان حاصل ڪيو ويندو آهي. پارو ۽ پاري وارا نامياتي مرڪب انسانن ۽ ٻين جانورن جي اعصابي نظام، مدافعتي نظام ۽ ڀکين (گردن) لاءِ زهر آهن. پاري جو زهر جو اثر، پاڻي ۾ حل ٿيندڙ پاري جي شڪلن (جهڙوڪ مرڪيورڪ ڪلورائڊ يا ميٿائل مرڪري) جي سڌي طرح يا بايو ميگنيفڪيشن جي ميڪانيزم ذريعي، ٿي سگهي ٿو.

پارو ٿرماميٽر، بيروميٽر، مينوميٽر، اسفيگمومانوميٽر، فلوٽ والوز، پاري جي سوئچز، پاري جي ريلي (relay)، فلوريسينٽ ليمپ ۽ ٻين ڊوائيسز ۾ استعمال ٿيندو آهي، جيتوڻيڪ هن تت جي زهريلي هجڻ بابت خدشن جي ڪري پاري تي مشتمل اهڙن اوزارن کي مرحليوار ختم ڪيو ويو آهي. اهو سائنسي تحقيق جي ايپليڪيشنن ۾ ۽ ڪجهه هنڌن تي ڏندن جي بحالي لاءِ املگم ۾ استعمال ۾ ٿئي ٿو. فلوريسينٽ ليمپ ۾ پاري جي وانپ مان گذرندڙ بجلي مختصر لهر واري الٽراوائلٽ روشني پيدا ڪري ٿي، جيڪا پوءِ ٽيوب ۾ فاسفور کي فلوروسينس ڪرڻ جو سبب بڻجندي آهي، جنهن سان نظر ايندڙ روشني پيدا ٿيندي آهي.

خاصيتون
طبيعي خاصيتون

Mercury is a heavy, silvery-white metal that is liquid at room temperature. Compared to other metals, it is a poor conductor of heat, but a fair conductor of electricity. in 

It has a melting point of −38.83 °C and a boiling point of 356.73 °C, both the lowest of any stable metal, although preliminary experiments on copernicium and flerovium have indicated that they have even lower boiling points. This effect is due to lanthanide contraction and relativistic contraction reducing the orbit radius of the outermost electrons, and thus weakening the metallic bonding in mercury. Upon freezing, the volume of mercury decreases by 3.59% and its density changes from 13.69 g/cm3 when liquid to 14.184 g/cm3 when solid. The coefficient of volume expansion is 181.59 × 10−6 at 0 °C, 181.71 × 10−6 at 20 °C and 182.50 × 10−6 at 100 °C (per °C). Solid mercury is malleable and ductile, and can be cut with a knife.

Table of thermal and physical properties of liquid mercury:
Temperature (°C)Density (kg/m3)Specific heat (kJ/(kg·K))Kinematic viscosity (m2/s)Conductivity (W/(m·K))Thermal diffusivity (m2/s)Prandtl NumberBulk modulus (K−1)013628.220.14031.24 × 10−78.24.30 × 10−60.02880.0001812013579.040.13941.14 × 10−78.694.61 × 10−60.02490.0001815013505.840.13861.04 × 10−79.45.02 × 10−60.02070.00018110013384.580.13739.28 × 10−810.515.72 × 10−60.01620.00018115013264.280.13658.53 × 10−811.496.35 × 10−60.01340.00018120013144.940.1578.02 × 10−812.346.91 × 10−60.01160.00018125013025.60.13577.65 × 10−813.077.41 × 10−60.01030.000183315.5128470.1346.73 × 10−814.028.15 × 10−60.00830.000186

Chemical properties
Mercury does not react with most acids, such as dilute sulfuric acid, although oxidizing acids such as concentrated sulfuric acid and nitric acid or aqua regia dissolve it to give sulfate, nitrate, and chloride. Like silver, mercury reacts with atmospheric hydrogen sulfide. Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury (spill kits also use activated carbon and powdered zinc).

Amalgams
Mercury dissolves many metals such as gold and silver to form amalgams. Iron is an exception, and iron flasks have traditionally been used to transport the material. Several other first row transition metals with the exception of manganese, copper and zinc are also resistant in forming amalgams. Other elements that do not readily form amalgams with mercury include platinum. Sodium amalgam is a common reducing agent in organic synthesis, and is also used in high-pressure sodium lamps.

Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact. Since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth (as in iron rusting), even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft.

Mercury embrittlement is the most common type of liquid metal embrittlement, as mercury is a natural component of some hydrocarbon reservoirs and will come into contact with petroleum processing equipment under normal conditions.

Isotopes

There are seven stable isotopes of mercury, with  being the most abundant (29.86%). The longest-lived radioisotopes are  with a half-life of 444 years, and  with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day.  occurs naturally in tiny traces as an intermediate decay product of .  and  are the most often studied NMR-active nuclei, having spins of  and  respectively.

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