percipitation

Question 1

percipitation

Answer 1

the formulation of an insoluble component from solution either by interaction of two salts (by chemical changes) or by temperature changes (physical changes) effecting stability is called percipitation

Question 2

crystallization and percipitation

Answer 2

-similar concepts, used as separation techniques
-both methods the end product is a solid and its nature can be controlled by manipulating varibles throughout the process
-p is a unit process in which a settleable and or/filterable solid is formed by the chemical joining of two or more inorganic dissolved chemical species, the objective of which is to remove one of the chemical species

Question 3

supernatant

Answer 3

the separated solid particles are called percipatate, while the remaning clear liquid above the percipitates are called as “supernatant”

Question 4

precipitant

Answer 4

cause of percipitation

Question 5

supernatant liquid

Answer 5

liquid remains in the vessel above the percipitation

Question 6

methods of percipitation

Answer 6

-organic solvent method
-pH change method
-double decomposition method

Question 7

Organic solvent method

Answer 7

-water insoluble substances or dugs are dissolved in water miscible organic solvent
-now the dissolved drug can be easily percipitated by adding water into the mixtue
-the general organic solvent are ethanol, methanol, glycol, propylene glycol, polyethylene glycol
-when suspention is dissolved in methanol, it is very easily percipitated by adding distilled water
-only physical change occur in this process

Question 8

pH change method

Answer 8

-only applicable to those substances in which solubltity are dependant upon pH
-(esterdiol suspention) is prepared by changing pH of the aqeous solution. Esterdiol drug is readily soluble in alaline media (NaOH and KOH) solution. however this drug is insoluble in acidic media (HCl, acetic acid or citric acid) with proper agitation. esterdiol is easily perciptated out in form of fine particles.
-insulin solution can also be prepared by pH change method. The PH change method is again a physical change
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Question 9

double decomposition method

Answer 9

-percipitation are formed in this method only by simple chemistry
-MgCO3 and CaCO3 are the common substances prepared by this method
high concentration solution produce coasrse percipetates, from which impurities can be removed by washing, but persipitates formed by dilute solution are much finer and it is much difficult to remove impurities from them. In many case the order of mixing solution can also effect the PPT formation

Question 10

applications

Answer 10

-the percipitaion method is used to produce very fine solid particles, about 0-1um
-it is also used to purify solid
-it provides a conveniant method of obtaining solid substances in he form of fine particles such as the percipitation of calcium carbonate
-in preparation of pharmaceutical dyes, paints, printing inks
-many consumer products are prodcuceed via percipitatin processes, such as magnetc recording meda, which contain ferric or chromic oxides and photographic materials
-percipatation has also played an important role in waste water treatment (removal of calcium salts)
-in metalurgy, percipitation from a solid solution is also usefull way to strngthen alloys, this process is known as solid solution strengthening