Wednesday, September 30, 2020

Properties Of Boric Acid

                Boric acid reacts with sodium hydroxide to form sodium metaborate and sodium tetraborate. 

                   H3BO3  +  NaOH  ———>  NaBO2  +  2H2O

                  4H3BO3  +  2NaOH  ———>  Na2B4O7  +  7H20

Action Of Heat:

              Boric acid heated above 170 degree Celsius to gives metaboric acid.

                                 4H3BO3  ———>  4HBO2  +  H20

              Boric acid heated above 300 degree Celsius to gives tetraboric acid.

                               4HBO2   ———>  H2B4O7  +  H2O

             Tetraboric acid heated above 330 degree celsius to gives boron trioxide.

                               H2B4O7  ———>  2B2O3  +  H2O

Action Of Ethyl Alcohol:

              Boric acid reacts with ethyl alcohol in the presence of concentrated sulphuric acid to form triethylborate. The ethyl borate burns with green edged flame.

                              4H3BO3  +  3C2H5OH   ———>   B(OC2H5)3  +  3H2O

Action Of Calcium Fluoride:

            Boric acid reacts with calcium fluoride in the presence of concentrated sulphuric acid to gives boron trifluoride.

                            2H3BO3  +  3CaF2  +  3H2SO4   ———>  2BF3  +  3CaSO4  +  6H2O

Tuesday, September 29, 2020

Preparation Of Boric Acid

 Boric Acid:

             A mixture of concentrated sulphuric acid reacts with borax to form boric acid.

Na2B4O7  +  H2SO4  +  5H2O ———>      Na2So4          +          4H3BO3

                                                          ( Sodium sulfate )        ( Boric acid ) 

Boric acid can be extracted from colemanite. 

Ca2B6O11  +  11H2O4  +  SO2  ———>  Ca(HSO3)2  +  6H3BO3

Tuesday, September 22, 2020

Uses Of Boric Acid

  • Boric acid is used in the manufacture of pottery glaze glass, enamels and pigments.
  • Boric acid is used as an antiseptic, insecticide and flame retardants.
  • Boric acid is used as a food preservatives.
  • Boric acid is used in the production of LCD flat panel display.
  • Boric acid is used to prevent existing wet and rot in timber etc....

Thursday, September 10, 2020

Uses Of Borax

 Borax Uses:

  • Borax is used fir the identification of colored metal ions.
  • Peroxoborate present in washing powder. It's a cleaning and bleaching agent.
  • Borax is a flux for soldering. And also acts as a good preservative.
  • In the manufacture optical and borosilicate glass, enamels and glazes for pottery.
  • Borax is used as fungicide, fire retardant and in softening water.
  • Borax is used for stiffening agent for candle wicks. 
  • Borax is used as antiseptic soaps.

Properties Of Borax

Properties Of Borax:

  • Borax is a white crystalline solid, less soluble in water but more soluble in hot water.
  • Borax dissolved in hot water to gives the alkaline solution of boric acid and sodium hydroxide.

                        Na2B4O7  +  7H2O  ———>  4H3BO3  +  2NaOH

  • On heating, borax loses its water of crystallization and swells up to form a puff mass. On further heating, it melts into a clear liquid which solidified to a transparent glass like bead. Which consist of sodium metaborate and boric anhydride. This glass bead is commonly called as borax bead.                                                                                

                       Na2B4O7.10H20 ———> Na2B4O7 ———> 2Na2BO2 + B2O3

  • Borax beads are used in laboratory to identify some metals in salts, through borax beads test. Nickel salts give brown colored bead. Cobalt slats give blue colored bead. White chromium salt gives green bead in flame.
  • Borax reacts with acids like sulphuric acid and hydrochloric acid to form sparingly soluble boric acid.
                              Na2B4O7 + 2HCl + 7H2O  ———> 4H3BO3  +  2NaCl

                              Na2B4O7  +  H2SO4  +  5H2O  ———>  4H3BO3  +  2Na2SO4

  • Borax reacts with Ammonium Chloride to form boron nitride.

                              Na2B4O7  +  2NH4Cl  ———>  2NaCl  +  2BN  +  B2O3  +  2H2O

  • Borax heated with ethyl alcohol and concentrated sulphuric acid, to forms vapors of triethylborane. When ignited these vapor burn with green edged flame.

                  Na2B4O7  +  H2SO4  +  5H2O ———> Na2SO4  +  4H3BO3

                  H3BO3  +  3C2H5OH  ———>  B(OC2H5)3  +  3H2O

Borax Preparation

 Borax  [Na2B4O7.10H2O]              

          Borax is a sodium salt of tetraboric acid. Fine powdered colemanite ( Ca2B6O11 ).    Is boiled with sodium carbonate ( washing soda ) solution. The insoluble calcium carbonate is filtered off ( CaCO3 ).  Then it is concentrated and cooled to get the crystals of borax. The sodium metaborate is treated with           CO2  gas which converts into borax.

Ca2B6O11  +  2Na2CO3  ———>  Na2B4O7     +      2NaBO2         +        2CaCO3

Colemanite                                  Borax                 Sodium                     calcium

                                                                            metaborate                carbonate

2NaBO2  +  CO2  ———>  Na2B4O7  +  Na2CO3

Wednesday, September 9, 2020

Uses Of Boron

 Boron Uses:

  • The compound of boron are boric acid, borax and boric oxide. These can be found in eye drops, mild antiseptics, washing powders and title glazes. Borax used to make bleach and food preservative.
  • Amorphous boron is used as a rocket fuel igniter.
  • In the manufacture of pyrex glass, boric acid is used
  • Sodium octaborate is a flame retardant.
  • Boron is essential for the cell walls of plants.
  • Boron has the capacity to absorb neutrons. This means the isotope of Boron-10 used to regulate nuclear reactors.

Chemical Properties Of Boron

                           The impure amorphous product a brownish black powder, was the only form of boron known for more than a century. Many of its compounds are electron deficient and has unusual type of covalent bonding which is due to its small size, high ionization energy and similarity in electronegativity with carbon and hydrogen. Pure crystalline boron may be prepared by reduction of its bromide or chloride with hydrogen on an electrically heated tantalum filament.

Boron Trihalides:

                 Boron reacts with halogen elements to form highly reactive trihalides. Boron trihalides and trimethylamine reacted to form complex. 

                  BCl3  +  N(CH3)3  ———>  (CH3)3N.BCl3

Formation Of Hydrides:

                  With hydrogen boron forms a series of compounds called boranes. The simplest borane is Diborane ( B2H6 ). Boron trifluoride react with sodium hydride around 450K ( Heat ) to form diborane.

                 2BF3  +  6NaH  ———>  B2H6  +  6NaF

Formation Of Boron Oxides:

                       Boron reacts with oxygen around 900K ( heat ) to  form its oxide. 

                   4B  +  3O2  ———>  2B2O3

Reaction With Acid And Alkali:

                        Boron is most easily converted into boric acid by treatment with acids like sulphuric acid and nitric acid.

                     2B  +  3H2SO4  ———>  2H3BO3  +  3SO2

                     B  +  3HNO3  ———>  H3BO3  +  3NO2

Boron reacts with sodium hydroxide to form sodium borate.

                    2B  +  6NaOH  ———>  2Na3BO3  +  3H2


Thursday, September 3, 2020

Boron Group Elements ( Group- 13 )

 Boron Family:

               The group 13, boron group consist of six elements. The elements are Boron ( B ), Aluminum ( Al ), Gallium ( Ga ), Indium ( In ), Thallium ( Tl ). The common property of the group is that each one of the elements has three electrons in the outer shell of their nuclear structure. Boron is the lightest element in this group. Relatively rare element. Boron is a metalloid.

Occurrence Of Boron Family:

  • Boron is a very low in abundance, composing only 0.0001% of the earth's crust.
  • Aluminium is the most abundant metal and occurs as oxides and also found in Aluminium silicate rocks. It composes about 8.3% of the earth crust.
  • Gallium is relatively rare element in the earth's crust. Gallium find in the earth with a wealth of 13 parts per molecule.
  • Indium is the 61st richest element in the world's covering.
  • Thallium is found in small amounts all over the planet. Thallium is extremely toxic and has no commercial use. The elements Ga, In, and Tl occurs as their sulphides.

Thursday, August 27, 2020


                 Some chemical elements exist in two or more different forms in the same physical state known as Allotropes of elements. In greek "allos" means another and trope means change. 

For example: Carbon exists as diamond and graphite. This phenomenon is called allotropism and the different forms of elements are called allotropes.

Allotropes of some elements:


Carbon           -- Diamond, Graphite, Amorphous carbon, Fullerenes, Graphene, Carbon nanotubes.

Oxygen          -- Dioxygen, Ozone, Octaoxygen.

Selenium        -- Red selenium, Gray selenium, Black selenium, Monoclinic selenium.

Phosphorus    -- White phosphorus, Red phosphorus, Violet phosphorus, Black phosphorus, Scarlet                                          phosphorus.

Sulphur          -- Rhombus sulphur, Monoclinic sulphur.

Metalloids :

Tellurium     -- Amorphous tellurium, Crystalline tellurium.

Boron.          -- Amorphous boron,  ⍺ - rhombohedral boron, β - rhombohedral boron, 𝛾 - orthorhombic                                boron, ⍺ - tetragonal boron, β -tetragonal boron.

Germanium  --  ⍺ - germanium, β - germanium.

Arsenic         -- Yellow arsenic, Gray arsenic, Black arsenic.

Antimony     --  Yellow antimony, Black antimony, Blue-White antomony.

Silicon.         --  Amorphous silicon, Crystalline silicon.


Tin        --  Gray tin, White tin, Rhombic tin, Sigma tin.

Iron      --  Ferrite, Austenite.

cobalt   --  ⍺ - cobalt, β - cobalt.    


Wednesday, August 26, 2020

Reduction Of Metal Oxides

          Extraction of metals from their respective ores. In this method we can get metal oxides again we adding some reducing agent and heated up. It will give pure metals.


     Smelting is a process of reduction of metal oxide to metal by carbon, carbon monoxide, or aluminum. In this metal oxide is heated above the melting point of the metal.


Oxide of ion can be reduced by carbon monoxide.

Fe2O3  +  3CO  ———>  2Fe   +   3CO2            

         Limestone ( CaO ) is a basic flux. Silica gangue present in the ore in its acidic nature. The limestone combines with silica gangue to form calcium silicate( slag ). 

  CaO    +      SiO2      ———>    CaSiO3

(Flux)       ( Gangue)                      (Slag)

             The concentrated ore ( copper pyrite ) heated in a reverberatory furnace. It will form metal sulphides FeS and Cu2S. Both are soluble and form a copper matte.

2CuFeS2  +  O2  ———>  2FeS  +  2Cu2S  +  2SO2

FeS oxidized to FeO.

FeS  +  O  ———>   FeO   +   SO2

Now the ferrous oxide ( flux ) reacted with the silica ( gangue ) to form ferrous silicate  ( slag ).

    FeO     +       SiO2       ———>      FeSiO3

  (Flux)        (  Gangue)                      (Slag)

The remaining copper sulphide is further oxidised to its oxide to form the metallic copper.

Cu2S  +  3O2  ———>  2Cu2S  +  2SO2

2Cu2O  +  Cu2S  ———>  6Cu  +  SO2

This metallic copper  has blistered appearance due to the evolution of   SO2  gas. This copper is called Blistered copper.

Reduction By Carbon:

        In this method oxide ( ZnO ) ore is mixed with coal ( Coke ) and heated strongly in a furnace. This process only applied to the metal which do not form carbides with carbon. 

Examples :

ZnO  +  C  ———>  Zn  +  CO

Mn3O4  +  4C  ———>  3Mn  +  4CO

Cr2O3  +  3C  ———>  2Cr  +  3CO

Reduction Of hydrogen;

              This process only applied to the metal which have less electro -positive character than hydrogen.

Ag2O  +  H2  ———>  2Ag  +  H2O

Fe2O4  +  4H2  ———>  3Fe  +  4H2O

Reduction By Metal:

B2O3  +  6Na  ———>  2B  +  3Na2O

Rb2O3  +  3Mg  ———>  2Rb  +  3MgO

TiO2  +  2Mg  ———>  Ti  +  2MgO

In this process metal oxides reduced by metal.

Conversion Of Ores Into Oxides

        Oxygen is more electronegative than other elements. So it is easier for oxides to accept an electron pair and get reduced.

Calcination :

        Calcination is the process of heating a substance in a limited supply of air or oxygen. During this process the water of crystallization present in the hydrated oxide escapes as moisture. Due to the thermal energy (Heat) we can change their chemical state and turn them into oxides. The hydroxides and carbonates are usually converted to oxides through this process. 

Fe2O3.3H2O  ———>  Fe2O3  +  3H2O

CaCO3  ———>  CaO  +  CO2

PbCO3  ———>  PbO  +  CO2

ZnCO3  ———>   ZnO  +  CO2

MgCO3.CaCO3   ———>  MgO  +  CaO  +  2CO2

Al2O3.2H2O  ———>  Al2O3  +  2H2O

Roasting :

      Roasting is the method of heating sulphide ore to a high temperature in the presence of air. In this method the concentrated ore is oxidized by heating it with excess of oxygen in a suitable furnace with in the melting point of the metal. the oxygen in the air reacts with the sulphide ores to give us oxide.

Example ;

2Zns  +  3O2  ———>  2ZnO  +  2SO2

2Cu2S  +  3O2   ———>   2Cu2O  +  2SO2 

2PbS  +  3O2  ———>  2PbO  +  2SO2

       Roasting also removes impurities such as arsenic, sulphur, phosphorus by converting them into their volatile oxides.

Examples :

4As  +  3O2  ———>  2As2O3

S8  +  8O2  ———>  8SO2

P4  +  5O2  ———>  P4O10