Some Important Compounds of Boron for IIT JEE

The Compounds formed by Boron for JEE Chemistry

There are many elements in the world which are useful in some or the other way. The scientists have been very much interested in seeing to it that they are discovering all the materials that are found in the Earth's crust as well as those which can be manufactured by man. There are still many elements which are yet to be found and processes are being developed to find them as well.

One of the elements which have been found to be very useful to human kind is Boron. There are many uses of boron which are very interesting. It has aided in the manufacture of many things and has been useful in many fields. Here are the characteristics of the element Boron:

1. Boron is the 5th element in the periodic table and belongs to the 13th group. It is placed in the 2nd period and is called as the group III A element.
2. The element in its isolated state without any kind of impurities weighs 10.811 grams and bears a density of 2.37 gm/cc (grams per cubic centimeter)
3. Speaking of the physical appearance, it is a solid at the room temperature and it is classified under the semi- metal elements in general.
4. This element melts at a temperature of 2348K and boils at a temperature of 4273K.

The compounds formed by Boron:

Boron is a very much reactive compound and there are many compounds of boron that are found in the nature. These compounds are found to be very much useful in the manufacture of things in various fields. Here are some of the important compounds of boron that are found in the nature:

1. Borax (Na2B4O7.10H2O)

Borax is one of those compounds of boron which is naturally found in many parts of the world. This commonly occurs as tincal and it contains around 55% of boron in its naturally occurring state. Tincal is abundantly found in India, Tibet and also parts of the U. S. like the California.

Here is the manufacturing process of Borax:

Borax from Tincal

Firstly, Tincal is mixed in water and is then left for concentration. After seeing to it that the solution is properly concentrated, it is left for crystallization which then forms Borax crystals. The borax gems, Na2B4O7.10H2O are then segregated from the solution and they are extracted as Borax compounds.

From other Minerals

While the above process is from a naturally occurring one, there are still other compounds from where borax can be extracted. For instance, elements like the boracite, boronatrocalcite, and colemanite are powered and made into fine crystals. These are then boiled with sodium carbonate arrangement. Borax is then solidified from the filtrate. Sodium metaborate is the compound which is first formed. This is converted into Borax by passing carbon dioxide through it. This is one of the many processes which are used to manufacture Borax.

The physical properties of Borax:

Borax is a crystalline solid and a lackluster which is soluble in cold water to some extent. When it is mixed with water of slightly higher temperatures, the Borax breaks down. According to the basic nature of the Boric acid solution, as it is alkaline in nature, it is found that boric acid is a very feeble acid. The compound borax is going to react with Hcl or H2So4 to give boric acid as the end products. When the entire setup for this particular formation is cooled down, the white crystals of boric acid are seen and they are extracted from the frame. When we take a close look at the chemical formula of Borax, we see that it has the water of crystallization attached to it. That means that when it is acted up on by heat, the compound is going to lose the water of crystallization and turns dry. The physical appearance of Borax is also going to change to a great extent when this happens. It becomes colorless, transparent, glass finished bead like structure of boric anhydride and sodium metaborate. It frames two hydrates: octahedral borax Na2B4O7. 5H2O and monoclinic borax Na2B4O7. 10H2O.

Uses of Borax

  • • Borax is used in the production of enamels and mainly the glass. It is also used in the production of drying oils, cleansers and ceramics.

  • • In the welding processes that are carried out, there has to be a flux and borax aids as a flux in such processes.

  • • In our day to day life, we see that the wick of the candle is made of a hard material. Borax is used in this.

  • • Borax is used in the manufacture of fabric softeners and washing powders as well.

  • • Borax also acts like a germicide.

  • Boric Acid (H3BO3):

    Boron also forms a feeble acid. There are many acids that arise depending on the quantity of water that is present. Orthoboric acid (boric acid), H3BO3 is one of the most important of all the acids that can be formed.

    Manufacture of Boric Acid:

  • From borax

  • When the compound Borax that is mentioned above reacts with either Hydrochloric acid (Hcl) or sulphuric acid, then Boric acid is formed. When the reaction is completed, the mixture is cooled so as to obtain the white powder like pieces of Boric acid.

  • By the hydrolysis process of compounds of boron:

  • Compounds like born nitrides, boron sulfides, boron halides and other such ones are made to undergo the process of hydrolysis which gives rise to the product- Boric acid.

    The characteristic features of Boric Acid

  • • Boric acid is a feeble acid and it is white and crystalline in its physical state. It is very delicate and lathery to touch.

  • • Boric acid is partially soluble in cold water but the solubility in hot or warmer water is comparatively very less.



  • Action of heat

    On action of heat, the boric acid is going to lose its water of crystallization and breaks down into metaboric acid at 370K and tetraboric acid at 430K. At the red hot temperaure boric acid forms boron trioxide as well.

    Boron is a very weak monobasic acid and is actually considered harmless to the skin. Coming to reaction with alkalis, the boric acid is found to form salts on reacting with the stronger alkalis. These salts so formed are known as the metaborates.

    Uses of boric acid:

  • • Just like the compound borax, boric acid is also used for the manufacture of enamel and ceramics coats.

  • • This is also used for the synthesis of borax and also other pigments.

  • • Preservation of food is very much important. Boric acid is used like a food preservative in the industry.

  • • For manufacturing borosilicate glass.

  • • While we are cleaning our eye lids, it is very much necessary to be very careful. Any strong chemicals will damage the eyes. Boric acid is considered apt as a medicine for the purpose of eyewash.  

  • Diboranes (B2H6)

    Diborane (B2H6) is one more important compound of the boron family. Boranes are those compounds which are just containing boron and hydrogen as the prime elements. Coming to the physical properties of Diboranes, it is a dry component which is very much unsafe for use. It is a highly responsive compound.

    When sodium borohydrate is oxidized with the compound iodine, the product of the reaction is diborane.

    When diborane is made to react with oxygen, then it results in a huge exothermic reaction which releases an enormous amount of energy of 1976kJ for each mole of diborane.

    Before the advent of technology, borane was used as a solid fuel in the rocket propulsion because of the exothermic reaction with water.

    Boron is a very useful element in the Periodic Table and forms many important compounds. Borate pentahydrate is considered to be the most significant boron compound. This compound is largely used in the manufacture of fiber glasses insulation and it is also used in the perborate bleach as well. Boron was discovered by two French chemists named Joseph-Louis Gay-Lussac and Louis-Jaques Thénard. Sir Humphry Davy, an English chemist, in the year of 1808 was independently influential in the discovery of boron. Boron-10 is a naturally occurring isotope of boron. Because of its good capacity of absorbing neutrons, it finds its uses in the manufacturing of control rods of nuclear reactors. It is also utilized as a neutron detector and as a radiation shield. 
    Boron filaments are lightweight but have high strength. This quality of the boron filaments is utilized by the aerospace industry. These are some of the important compounds formed by boron and their respective uses. It should be stated that this is one of the most useful discovery by mankind as it has been aiding many fields for that matter. There are also other compounds like the nitrides of boron which are of less significance.