SODIUM HYDROXIDE OR CAUSTIC SODA (NaOH) || CAUSTIC SODA || SODIUM HYDROXIDE || NaOH ||

-

SODIUM HYDROXIDE OR CAUSTIC SODA (NaOH):

PREPARATION: It is the most easily  manufactured by one of the following process:

(a) Methods involving sodium carbonate(Na2CO3) as a starting material :

» Gossage process (causticising process) :

          Na2 CO3+ Ca(OH)2 → Ca CO3 + Na OH

The most suitable concentration of sodium carbonate(Na2 CO3) taken in this process is about 15% – 20%. The caustic soda(Na OH) produced by this process is not pure and contains some amount of calcium carbonate(Ca CO3) , sodium carbonate and calcium hydroxide(Ca(OH)2 )as impurities.

» Lowig’s process :

         Na2 CO3+  Fe2 O3 → 2 Na Fe O2 + CO2

The sodium ferrite(Na Fe O2) is cooled and thrown into hot water, the hydrolysis of sodium ferrite(Na Fe O2) occurs forming Na OH.

        2 Na Fe O2 + H2O → 2 Na OH + Fe2 O3

» Methods involving sodium chloride as starting material :

Electrolysis(treatment with electricity) of sodium chloride(Na Cl) solution occurs according to following principle.

Na Cl →Na+ + Cl¯       ;    H2O→  H+  + OH¯

On passing electricity,  Na+ and H+ ions move towards cathode and Cl¯ and OH¯ ions move towards anode.

The discharge potential of H+ ions is less than Na+ ions, thus hydrogen ions get discharged easily and hydrogen gas is liberated. Similarly, at anode Cl ions are easily discharged as their discharge potential is lesser than that of OH¯ ions. Cl2 gas is, therefore, liberated at anode.

It is necessary that chlorine(Cl) should not come in contact with sodium hydroxide(Na OH) during electrolysis, otherwise following reaction takes place.

       2Na OH + Cl2 → Na Cl + Na ClO + H2O

To solve this problem, the anode is separated from the cathode in the electrolytic cell either by using a porous(hole-like) diaphragm or by using a mercury(H g) cathode. 

Comments

Post a Comment

Popular posts from this blog

QUANTUM NUMBERS (Principal, Azimuthal, Magnetic and Spin)

-
Image
                  QUANTUM NUMBERS  Orbitals represent regions in the space around the nucleus where the probability of finding the electron is maximum. A large number of electron orbitals are possible in atom. These can be distinguished by their size, shape and orientation of the orbitals. To describe each electron in an atom in different orbitals, we need a set of three numbers known as quantum numbers. These are designated as n, l and m. In addition to these three numbers another quantum number is also needed which specifies the spin of the electron. These four numbers are called quantum numbers. These are discussed below: 1. Principal quantum number (n) :  This quantum number determines the main energy shell or level in which the electron is present. It is denoted by n. It can have whole number values starting from 1 such as n = 1, 2, 3, 4 ... This quantum number also identifies as shell. The shell with n 1 is called the first sh...
Read more

Diagonal Relationship between Beryllium and Aluminium || Relation between Beryllium and Aluminium

-
  Diagonal Relationship between Beryllium and Aluminium The ionic radius of Beryllium (Be 2+) is estimated to be nearly 31 pm; the charge/radius ratio Or e/m ratio is nearly the same as that of the Al 3+ ion. Hence beryllium resembles aluminium in these ways. Some of the similarities are given below: » Like Aluminium, Beryllium(be) is not readily attacked by acids H+ donor because of the formation of an oxide film on the surface of the metal by reacting with oxygen, i.e. they are rendered passive by nitric acid. » Beryllium hydroxide[[Be(OH)4]2] dissolves in excess of alkali to give a beryllate ion, [ Be(OH)4]2– just as aluminium hydroxide[Al(OH)3] gives aluminate ion, [Al(OH)4] » The chlorides of metals beryllium and aluminium have Cl– bridged chloride structure in vapour phase. Both the chlorides are soluble in organic solvents and are strong as Lewis acids They are used as Friedel Craft catalysts. » Beryllium(Be) and aluminium(Al) ions have strong tendency to form complexes, (Be...
Read more

Math question

-
Image
A tower, x metre, has a flagstaff at its top. The tower and flagstaff subtends equal angles at a point distant y metre from the foot of the tower. Then find the length of the flagstaff ( in metre). 
Read more

Solar System, Planets, Moons, Asteroid Belt,Kuiper Belt and Oort Cloud, Comets and Meteoroids

-
Image
 The solar system consists of the Sun, which is a star at its center, and all the celestial bodies bound by its gravitational pull. These bodies include planets, moons, asteroids, comets, and other objects. Key Components of the Solar System: The Sun : The Sun is the center of the solar system and contains about 99.86% of its mass. It is a star primarily composed of hydrogen and helium, providing the heat and light that sustains life on Earth. Planets : There are eight recognized planets in the solar system: Mercury : The closest planet to the Sun, known for extreme temperature variations and no atmosphere. Venus : Similar in size to Earth but with a thick, toxic atmosphere and surface temperatures hot enough to melt lead. Earth : The third planet from the Sun, the only known planet to support life, with water and a breathable atmosphere. Mars : Known as the Red Planet, it has a cold, dry surface and signs of past water. Jupiter : The largest planet, a gas giant, w...
Read more