exsiccation

Question 1

definition

Answer 1

-the process of removing water of crystallization from substance and temperature is reuired to remove water from different compounds
-it may be regaded as process of effloresence controlled and accelerared but is applied in cases where water is not normally lost by effloresence

Question 2

process

Answer 2

-may be carried out by taking a weighed amount of the substance in a tarred dish.
-it is then heated on water bath, sand bath or in an oven with contineous stirging until a constant weight is obtained and there is no further loss in weight
-no further loss is weight inidicates that exsicceartion has been copleted and no further loss can take place

Question 3

principle

Answer 3

the principle incolved in this proces are the same as the process of effloresence

Question 4

objective

Answer 4

-to reduce the bulk of substance
-preparing pills which may contain any of the substance (having water of crystallization) e.g. ferrous sulphate, potassium alum etc
-this process is particularily performed to expel the water of crystallization and to increase the comparative strength of the exsiccated chemical to the crystalline chemical

Question 5

example

Answer 5

the temperature required to remove the water of cystallaization is very important and varies widely
-for example in CuSO4 %H2O when heated at 30C loses two molecules of water forming Cu2SO43H2O
-at 100C it loses two more water molecules resulting in CuSO4H2O
-the last water molecule is removed at 200C thus forming anhydrous CuSO4

Some exsiccated substances are not necessarily anhydrous.
-For example, ferrous sulphate (FeSO47H:O) when heated at about 100-105°C loses 6
molecules of water of crystallization.
-When further heated to remove the last water molecule, its decomposition takes place.
-Hence, FeSO4 H2O is called exsiccated ferrous sulphate.

If its exsiccation is carried out under vacuum, then anhydrous FeSO, can be obtained below
100°C.
-The examples of exsiccated salts used in pharmacy are exsiccated ferrous sulphate,
exsiccated copper sulphate, exsiccated sodium sulphate, exsiccated magnesium sulphate,
exsiccated sodium carbonate, exsiccated sodium phosphate and exsiccated alum etc.
-As the exsiccated salts are very hygroscopic, they must be stored in air-tight containers.

Question 6

methods

Answer 6

there are general two methods
1-in one their humid parts are exhaled by heating
-cooling/boiling
2-in other water is absorbed by different substances

Question 7

cooling/boiling

Answer 7

this is a pocess of drying by heating also named as process of boiling. during this process it is important to take care of the heat lel, at the close of the operation (process) the fire should be gradually surpressed otherwise the matter being left dry will be heated beyond the adjusted degress and then the excissacted substance can be damaged
-this methods is used for fluids only

Question 8

isolation

Answer 8

-isolation of properly exhalaltion is effected by exposing the substance to the sun, till it is sufficiently dried. there is nothin particularily nessecary to be observed, except to incease the surface of the matter to be much exposed to the sun
-for in proportion the process of exsiccation will be completed in greater or lesser time
-usefull for solid and liuquids

Question 9

torrification

Answer 9

-torrification sometime called toasting is process of exposing solid substances to the heat of the fire at such distance that it will not be endagered. they are being burnt in order to make them of sufficient dryness to make them in powdered form
-only for solids

Question 10

conditions requerd for exsiccation

Answer 10

temp
moisture

Question 11

temperature

Answer 11

because as we increase or decrease the temperture the molceucles of water are evaporated from the crystals specific temperature for specific crystal remove specific amount of water molecule

Question 12

moisture

Answer 12

-if the enviroment is notmoisture free then after exsicating the crystal the exsiccation produced might again react with the water contents of the enoviroment and again become hydrated
-after exsiccating a cystal, we should immediteky transfer the exsiccated product in a close air tight containers of bottles

Question 13

applcation

Answer 13

-Exsiccation is carried out to get an anhydrous product required in the formulation of
pharmaceuticals.
-After the removal of water, the bulk and weight of the drug is reduced and they can be easily
administered/used in manufacturing.
-Potency of drug is increased after the removal of water.
-After exsiccation fine powder is obtained which is easy to handle.
-These exsiccated chemicals are use in the formation of inhalations, sprays, syrups, mouth washes.
-These exsiccated chemicals are used to prepare medicines to treat microbial, malarial, fungal and
algal infections.
-Some of these exsiccated chemicals are used to treat constipation.