The metal sodium (symbol Na) is an element of the first group of the periodic table, that of Alkaline metals. These metals have a single one electron in the external shell and tend to sell it easily: therefore sodium is extremely reactiveespecially with thewaterfallwith which he produces through an exosterical sodium hydroxide reaction (Naoh), gaseous hydrogen (H2) and heat sufficient to trigger the explosion. In this article we see in detail the chemistry of the sodium, where it is in nature and its main applications.
The explosive reaction of the sodium with water
To understand why the sodium explodes in contact with water, we must know the structure of the sodium atom. The sodium atom presents 11 protons And 11 electronswhich are distributed on three levels: 2-8-1. The third level electron is little linked to the nucleus and comes ceded With ease. In fact, as soon as the sodium enters contact with water, the sodium gives off its electron through the following chemical reaction.
2 na + 2 h2Or ⟶ 2 nah + h2 + heat
The heat developed then allows hydrogen to react with theoxygen Present in the air, burning and causing the explosion.
2 h2 +O2⟶ 2 h2OR
Where the metal sodium is found in nature and how it is obtained
The pure sodium it is not found never In nature, since it is always linked to other elements. For example, if combined with chlorineforms the sodium chloridebetter known as kitchen salt or sea salt. For this reason, kitchen salt does not explode In contact with water: sodium is linked to chlorine and is not found in its elementary form.
Most of the sodium present in nature are found in oceansin the form of sodium chloride. In fact, the oceans contain about 4 × 10 kg of this salt, or 40 billion billion kilograms. If we collect all this salt, we would get a giant cube with a side of 265 km, as large as the distance that separates Milan from Venice.
In any case, sodium can also be found in other minerals, such as silicates, sulphates and carbonates. In fact, the chemical symbol “Na“derives from” Natrium “, which refers to the”Natrun“, The Arabic name for hydrated sodium carbonate, a mineral that contains sodium.
Consequently, to obtain pure sodium, several chemical processes are used that separate sodium from the other elements. One of these is the Downs processin which sodium chloride is merged (i.e. liquid made). In this liquid, two electrodes are inserted and a potential difference is applied. Thanks to this, sodium chloride gives up a sodium electron, which is deposited on one of the electrodes in the form of pure sodium, while on the other electrode pure gaseous chlorine is formed.
The sodium cation is reduced to the cathode Na⁺ → na (l); The anion chloride oxidizes the anion Cl⁻ → ½ cl₂ (G).
What is metal sodium for
Metallic sodium is used in laboratories of research for experiments specific, in the metallurgy for the extraction of the titanium (Ti) and also in some reactors nuclear as a refrigerant liquid. A very promising research field concerns the batteries to sodium. Today, the most common batteries are those al lithiumbut lithium is a “Critical Raw Material“, So we try to replace it with sodium, which is much more abundant. Recently, a team of researchers from the Korea Advanced Institute of Science and Technology has developed a prototype sodium battery that showed good performance.
However, sodium batteries have some disadvantages compared to the lithium ones. For example, they have one density energy inferiorwhich means that they transport less energy per unit of weight. To make a comparison, a typical sodium battery has an energy density of about 160 Wh/kg, while a commercial lithium battery can reach around 250 WH/kg. This involves less autonomy for sodium batteries.
Despite this, the research on sodium batteries is a lot promising. In the future, they could represent a cheaper and sustainable alternative, particularly in sectors where the same power as lithium batteries is not necessary.
