With many chemical compounds, we come across very often, without even noticing it. One of them is potassium nitrate, or Indian saltpeter. Crystalline powder has firmly entered our life: we eat it (in the form of additives to various products), we use it in agriculture as a very valuable and useful fertilizer, well, we are just happy to look at some products in which it is present (fireworks).
Potassium nitrate: formula and description
This is an inorganic compound having the formula KNO3. - salt formed by nitric acid and sodium. Its crystals do not have color and smell. The substance is not volatile, but has slightly pronounced hygroscopic properties (that is, the ability to absorb moisture even from the air, but in small amounts). Potassium nitrate is practically non-toxic and harmless to humans and animals. The crystals have an elongated needle-like shape. Very well soluble in water (with the help of electrolysis from it are allocated potassium), as well as in hydrazine, glycerin, liquid ammonia. Sometimes a method of recrystallization is used to purify potassium nitrate.
Potassium nitrate (KNO3 ) in the natural environment occurs mainly in the form of a mineral of nitrolite. Its largest deposit is in India. Hence the second name of the compound - Indian saltpeter. The mineral is formed as a result of a long process of decomposition of nitrogen-containing substances, the ammonia released during this process is bound by specific nitrobacteria. This reaction occurs at high air temperatures, which determines the prevalence of this mineral in countries with a hot climate and high humidity.
Potassium nitrate (KNO formula3 ) is a sufficiently strong oxidant. In the shredded state, it reacts very actively and sometimes explosively with combustible materials and some reducing agents. In reactions involving certain organic compounds, it is also capable of igniting them. Saltpeter is very unstable and decomposes when exposed to temperature with the formation of nitrites and oxygen. Not an exception and potassium nitrate (equation: 2KNO3 → 2KNO2 + O2 ↑). This property of the connection indicates its very high fire hazard, which requires compliance with special storage rules.
The oldest method of obtaining
Potassium nitrate is a salt, which began to be received in the Middle Ages. For this, large compost or manure piles were used, they were called nitrites. They were made using limestone, various construction debris, interlayers of brushwood and straw, to provide access to oxygen. Above, to keep inside all of the evolved gases, they were sealed with turf. When organic began to decompose and decay actively, ammonia was released, which did not go outside, but remained in the layers of brushwood and straw, gradually undergoing the process of nitrification and transformation first into nitrogenous and then nitric acid. She, in turn, entered into a chemical interaction with the limestone in the compost pile and gave calcium nitrate as a result. Then it was leached with ordinary ash (potash). Calcium carbonate precipitated and a solution of potassium nitrate was obtained. It was used primarily for the preparation of gunpowder. This is reflected by the following reaction:
There are several ways of obtaining this substance. Here are the most commonly used and common ones:
- Nitric acid is neutralized with potassium hydroxide.
- Absorption of nitrous gases with potassium hydroxide.
- The conversion method, based on the decomposition of sodium nitrate with potassium chloride.
Application in agriculture
Indian saltpeter is actively used in many areas of human activity. The main direction is agriculture, where potassium nitrate is used as a valuable fertilizer. It contains two components that are extremely necessary for plants for their active development. If they are introduced separately, they mutually interfere with each other in normal assimilation, and if together - the process proceeds without any complications. This fertilizer dissolves very quickly in the soil solution, which is also a big plus, the exposure time is minimized. The introduction of potassium nitrate under the fruit trees in summer and autumn increases their cold resistance and frost resistance.
Other areas of use
The second sphere, where potassium nitrate is actively used, is the production of smoky powder, which at the present time in its bulk goes to the production of pyrotechnic products (military, specialized or entertaining).
The nitrate in question is also used in the manufacture of solid propellant, also called caramel, because of its use in the production of sugar (sorbitol). It is 65% composed of potassium nitrate.
Strong oxidizing properties of Indian saltpeter have found application in metallurgy, namely in the process of processing ores containing nickel. Also, this substance is actively used in the field of the glass industry, mainly for clarifying the crystal, increasing the strength of the product. Indian nitrate is also used in the manufacture of enamels, other varnish-and-paint products.
One of the least effective and useful areas for people, where potassium nitrate is used, is the food industry. There it is known by the code name E252 (preservative). It is used to prolong the shelf life of products, since potassium nitrate slows down the process of reproduction of bacteria and various fungi. This substance is actively added to cheeses (hard, semisolid, soft), sausages and meat products, canned fish, pates made from goose liver. In addition, this additive improves the color of the product. It is enough to recall the beautiful, but absolutely unnatural pink color of the sausage.
It is important to extract the following information: the supplement E252 is a carcinogen, that is, a substance that contributes to the development of cancer. Despite this, it is authorized for use on the territory of the Russian Federation and the countries of the Eurozone. This is the very case when chemistry goes against a person.