Facts About Lithium - Properties and Uses
Lithium is a silvery white alkali metal that can be found in small quantities in rocks. It does not occur in its elemental form but it can be found as a component of minerals and salts present in rocks and in brine water in the oceans.
The name Lithium is derived from the Greek word “Lithos” meaning stone. In 1817 Johan August Arfwedson discovered Lithium from a Swedish iron mine. He found Lithium in the petalite ore and in minerals such as spodumene and lepidolite.
Eventhough Arfwedson discovered Lithium he was not able to isolate Lithium from the mineral salts. It was William Thomas Brande and Sir Humphry Davy who isolated lithium through electrolysis of lithium oxide in 1818.
Properties of Lithium
Lithium in the pure form is an element belonging to the alkali group of metals. It is represented by the symbol “Li” and has an atomic number 3 with an atomic weight of 6.941. It has a melting point of 179 degree Centigrade and a boiling point of 1,317 degree Centigrade.
Lithium element is silvery-white in color and so soft that it can be cut with a knife. It reacts strongly with water and air.
When Lithium is exposed to air it reacts with oxygen in the air and forms lithium oxide and turns into a blackish-gray color. Therefore, it has to be stored in mineral oil to prevent such oxidation.
When a piece of Lithium is added to water, it floats on water because it is less dense than water and at the same time it reacts vigorously with water producing hydrogen gas and lithium hydroxide. Lithium hydroxide dissolves in water and the hydrogen gas escapes into air.
This metal has a very low density of 0.534 g/cm cubed and can float in hydrocarbon oils. It is the least dense of all solids under standard conditions.
Lithium is highly flammable and bursts into crimson colored flames when thrown into the fire.
Fires involving Lithium are difficult to put out and require Class D Fire Extinguishers. Class D Fire Extinguishers use powders to put out fires involving metals that are highly combustible such as lithium, magnesium, sodium and aluminium.
Group 1 elements in the Periodic Table are known as Alkali Metals. They react vigorously with water and air. Due to their highly reactive nature these elements have to be stored in mineral oil in their pure form.
Extraction of Lithium
Lithium is most commonly found in combination with aluminum, silicon and oxygen forming minerals called spodumene or petalite/castorite.
Extraction from Minerals
The mineral forms of Lithium are heated to a high temperature in the range between 1200K to 1300K to crumble them. After this process any one of the following three methods are used to extract Lithium.
1. Sulfuric acid and sodium carbonate are used to precipitate iron and aluminum from the ore, then sodium carbonate is applied to the remaining material thereby allowing the lithium to precipitate in the form of lithium carbonate. This is then treated with hydrochloric acid to form lithium chloride.
2. Limestone is used to calcinate the ore and then leached with water forming lithium hydroxide. This lithium hydroxide is treated with hydrochloric acid to form lithium chloride.
3. Sulfuric acid is added to the crumbled ore and then leached with water forming lithium sulfate monohydrate. This is treated first with sodium carbonate to form lithium carbonate and then treated with hydrochloric acid to form lithium chloride.
The lithium chloride obtained from the above three methods is subject to an oxidation-reduction reaction in an electrolytic cell to separate the chloride ions from the lithium ions.
Extraction from Salt Water
Salt water bodies also known as brines contain lithium chloride which is extracted in the form of lithium carbonate. Briny lakes also known as salars have the highest concentration of lithium. The salars with the highest concentration of lithium are situated in Bolivia, Argentina and Chile.
Salt water is let into shallow ponds and allowed to evaporate for over a year or more. The water evaporates leaving behind lithium and other salts. Lime is used to remove the magnesium salt and the solution is then treated with sodium carbonate so that lithium carbonate can be precipitated out of the solution.
Why Lithium is Highly Reactive
In an atom the electrons spin around the central nucleus in separate shells also known as orbitals. Shell number one can hold two electrons, shell two and three can hold a maximum of eight electrons. When one shell is full the electrons that are further added occupy the next shell.
In the above diagram the pink circle represents the first shell, the blue circle represents the second shell and the green circle represents the third shell.
The atomic number of a Lithium atom is three that means that there are three electrons in a Lithium atom.
There are two electrons in the first shell and only one electron in the second shell and no electrons in the third shell.
Lithium is highly reactive because of its electron configuration. Lithium has a single valence electron in the second shell that is easily released to create bonds and form new compounds.
For example, two atoms of Lithium bonds with one atom of oxygen to form Lithium oxide. One atom of Lithium bonds with one atom of fluorine to form Lithium fluoride.
Lithium is supposed to be one among the three elements to be produced in significant quantities during the Big Bang. The formation of these elements took place within the first three minutes of the existence of the Universe.
Uses of Lithium
Lithium metal in the pure form and its derivatives have many uses in manufacturing industries and in the field of medicine.
1. Lithium Hydroxide is used as a thickening agent to manufacture greases that are used as lubricants for industrial applications.
2. Lithium is used in the manufacture of batteries and rechargeable batteries specially for electronic gadgets. Lithium ions have a high capacity to store energy and this property makes lithium highly suitable in the manufacture of rechargeable batteries. Even though Lithium batteries are light weight and have a high capacity to store electrical energy, it is highly flammable.
3. The solid form of Lithium Hydroxide is used to absorb carbon dioxide in the space shuttles where astronauts live. Lithium Hydroxide absorbs the carbon dioxide and releases oxygen into the surrounding air thereby refreshing the air that the astronauts breathe.
4. Lithium is used as a coolant in nuclear reactors. Li-7 (Lithium-7) is used to reduce the corrosion in the steam generators of the nuclear reactors.
5. Lithium Chloride is a solid substance that has an enormous capacity to hold water, this property of lithium chloride makes it useful for air-conditioning purposes and as an antifreeze agent.
6. Lithium is used in the manufacture of aluminum, magnesium and lead alloys. The addition of lithium helps to make the alloy lighter and more stable.
7. Lithium is used as an alloying agent to synthesize organic compounds.
8. It is used as a flux to facilitate fusing of metals during welding and soldering. Lithium is also used as a flux in the manufacture of ceramics, enamels and glass.
9. Alloys of Lithium with aluminum, cadmium, copper, and manganese are used to make aircraft parts.
10. Lithium is used in the treatment of bipolar disorder, depression, schizophrenia, and for treating eating and blood disorders.
Questions & Answers
How is lithium used in the renewable energy sector?
Lithium-ion batteries have a high electrochemical potential and energy density when compared to other batteries. This makes lithium-ion batteries the most efficient solution for the storage of renewable energy and as a source for mobile power.
© 2018 Nithya Venkat