What happens when lithium nitrate is heated



properties
Generally
Name, symbol, atomic number Lithium, Li, 3
seriesAlkali metals
Group, period, block1, 2, p
Look silvery white / gray
Mass fraction of the earth's envelope 0,006 %
Atomic
Atomic mass 6,941 u
Atomic radius (calculated) 145 (167) pm
Covalent radius 134 pm
Van der Waals radius 182 pm
Electron configuration [He] 2s1
Electrons per energy level 2; 1
1. Ionization energy 520.2 kJ / mol
Physically
Physical state firmly
Modifications 1
Crystal structure body-centered cubic
density 0.535 g / cm3
Mohs hardness 0,6
magnetism paramagnetic
Melting point 453.69 K (180.54 ° C)
boiling point 1615 K (1342 ° C)
Molar volume 13,02 · 10−6 m3/ mol
Heat of evaporation 145.92 kJ / mol
Heat of fusion 3 kJ / mol
Vapor pressure

1,63 · 10−8Pa at 453.7 K.

Speed ​​of sound 6000 m / s at 293.15 K.
Specific heat capacity 3582 J / (kg K)
Electric conductivity 10,8·106S / m
Thermal conductivity 84.7 W / (m K)
Chemically
Oxidation states +1
Oxides (basicity) Li2O (strongly basic)
Normal potential −3.04 V
Electronegativity 0.98 (Pauling scale)
Isotopes
NMR properties
safety instructions
Hazardous substance labeling
from RL 67/548 / EEC, Appendix I.
R and S phrases R: 14 / 15-34
S: (1/2) 8-43-45
As far as possible and customary, SI units are used.
Unless otherwise noted, the data given apply to standard conditions.

lithium [ˈLiːtiʊm] (from Greek λίθοςlíthos “Stone”) is a chemical element with the symbol Li and the atomic number 3. The element was given the name lithium because, unlike sodium and potassium, it was discovered in rock. It is the alkali metal of the second period of the periodic table of the elements. Lithium is a light metal and has the lowest density of solid elements under standard conditions. When it comes into contact with the skin, it reacts with moisture and thus leads to severe chemical burns and burns. Its compounds are harmful to health, but to a far lesser extent than those of its period neighbor, beryllium.

Lithium was discovered by Johan August Arfwedson in 1817. Due to its high reactivity, it does not occur elementally in nature. At room temperature it is only stable for a long time in completely dry air; in moist air, a matt gray lithium hydroxide layer quickly forms on the surface. It slowly reacts to lithium nitride even in dry air. As a trace element, it is a common component of mineral water in the form of its salts.

Small amounts of lithium are present in the human organism; however, the element is not essential and has no known biological function. Nevertheless, some lithium salts have medicinal properties and are effective in treating bipolar affect disorders, mania, depression and cluster headaches.

history

 

The lithium-containing mineral petalite was first discovered by the Brazilian scientist José Bonifácio de Andrada e Silva at the end of the 18th century. The Swede Johan August Arfwedson is considered to have discovered lithium. In 1817 he discovered the presence of a foreign element in the mineral spodumene (LiAl [Si2O6]) and lepidolite (LiAl [Si4O10]) when he analyzed mineral finds from the island of Utö in Sweden. In 1818 it was the German chemist Christian Gottlob Gmelin who noticed that lithium salts give a red flame color. Both scientists failed attempts to isolate this element in the years that followed.

This was achieved for the first time by William Thomas Brande and Sir Humphrey Davy using an electrolytic process from lithium oxide (Li2O) in 1818. Robert Bunsen and Augustus Matthiessen then produced larger quantities of the element in 1855 by electrolysis of lithium chloride (LiCl). The German metal company (today: GEA Group) started the first commercial production of lithium in 1923 by means of electrolysis of a melt of lithium and potassium chloride (KCl).

In 1917 Wilhelm Schlenk synthesized the first organolithium compounds from organic mercury compounds.[2]

Occurrence on earth

It has a share of about 0.006% of the earth's crust.[3] It is therefore much rarer than many comparably light elements such as helium or carbon.

Lithium occurs naturally in some minerals. The most important are amblygonite (LiAl [PO4] F), lepidolite (KLi2Al [(Al, Si)3O10] (F, OH)2), Petalite (castor; LiAl [Si4O10]) and spodumene (triphane; LiAl [Si2O6]). These minerals have a lithium content of up to 9% (for amblygonite). Other, rarer lithium ores are cryolithionite (Li3N / A3[AlF6]2), which has the highest lithium content of all minerals, triphyline (Li (FeII, MnII) [PO4]) and zinnwaldite (KLiFeAl [AlSi3O10] (F, OH)2). Lithium minerals are found in many silicate rocks, but mostly only in low concentrations. There are no large deposits. Since the extraction of lithium from these minerals is associated with great effort, they no longer play an essential role in the extraction of lithium or lithium compounds. Some of them are still mined, ground and used in the glass industry.

Lithium salts are also widely found in brine, mostly salt lakes. The largest technically exploitable lithium deposits are located in Chile (Salar de Atacama) and Argentina, others in the USA (North Carolina and Nevada), Canada, Australia, Zimbabwe and China (Tibet).

The most important source of lithium today, however, is the lithium salts that are produced as a by-product of the extraction of potassium carbonate (potash) and borax.

Various plants such as tobacco or buttercups absorb lithium compounds from the soil and enrich them. The average proportion of the dry matter of plants is between 0.5 and 3 ppm. In the water of the world's oceans, the mean concentration is 180 ppb and in river water only around 3 ppb.

Occurrence outside the earth

After the Big Bang, there is also a significant amount of the isotope in addition to hydrogen and helium isotopes 7Li emerged. Most of this is no longer available today, because in stars lithium was fused with hydrogen in the process of the proton-proton reaction II and was thus consumed.[4] In brown dwarfs, intermediate stages between stars and planets, however, mass and temperature are not high enough for hydrogen fusion; their mass does not reach the necessary size of about 75 Jupiter masses. The lithium produced during the Big Bang was thus preserved in brown dwarfs. For this reason, lithium is also a relatively rare element extraterrestrially, but can be used to detect brown dwarfs.[5]

Extraction and presentation

Lithium carbonate is precipitated from lithium-containing salt solutions by evaporating the water and adding sodium carbonate (soda). To do this, the brine is first concentrated in the air until the lithium content exceeds 0.5%. The sparingly soluble lithium carbonate is precipitated by adding sodium carbonate:

.

In terms of volume, in 2006 outside the USA was 21,100 t[6] Lithium minerals mined and predominantly as lithium carbonate (Li2CO3) traded. Of these, 8000 t are from Chilean and almost 4000 t from Australian mines.

To obtain metallic lithium, the lithium carbonate is first reacted with hydrochloric acid. This creates carbon dioxide, which escapes as a gas, and dissolved lithium chloride. This solution is concentrated in a vacuum evaporator until the chloride crystallizes out:

The devices for the extraction of lithium chloride must be made of special steels or nickel, as the brine is very corrosive. Metallic lithium is produced by fused-salt electrolysis at 352 ° C