Tag: world energy needs

Since crystallization generally produces salts which are crystalline in state or $100$ percent purity in state.

Two compounds which have different solubilities in a solvent S can be separated from each other by Fractional Crystallisation. The process involves a series of repeated-crystallisations. The mixture of the two compounds in the solvent S is heated so as to make it saturated. When the hot solution is allowed to cool, the less soluble substance crsytallises out first while the more soluble substance remains in the solution. The crystals of first compound are separated from the mother liquor and the mother liquor is again concentrated and allowed to cool when the crystals of the 2nd compound are obtained.

Separation of a mixture into its components whose boiling points are different is called Fractional distillation.
This method is used for separating a mixture of two or more volatile liquids both having close boiling points. The boiling points of two components differ by 10-15 K. For example, acetone and methanol with boiling points 329 K and 338 K can be separated  by this method. This method is used for distillation of petroleum, coal tar and crude alcohol.

During fractional distillation, light oil or crude naphtha is collected upto 170$^o$.

90% benzol is named so because 100. c.c of the fraction when distilled below 100 deg C gives 90 c.c of distillate.
90% benzol contains 70% benzene, 24% toluene and 3-5% xylene.

Anthracene, phenanthrene, etc. represent the chief constituents of green oil.

Cresols, naphthalene, etc. represents the chief constituents of Creosote oil.

Ammonia liquor is prepared by dissolving Ammonia in water. Ammonia liquor is also known as ammonia water or some times known as ammonium hydroxide.
In aqueous solution, ammonia deprotonates a small fraction of the water to give ammonium and hydroxide according to the following equilibrium:
$ NH _3 +H _2O\rightarrow NH _4^{+} + OH^{-}$

During fractional distillation,  carbolic oil or middle oil is collected up to 170 - 230 $^o$.

During fractional distillation of coal-tar, the pitch is obtained as a residue.