Colliods and crystalloids.
Colloidal: -
A colloidal is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called dispersion medium.
Colloidal particles are larger than simple molecules but smaller enough to remains suspended .their range of diameter is between 1and 1000nm (10-9 to 10-6m).
Classification of collides: -
a) Lyophillic colloids: -
The word ‘lyophillic’ means liquid loving. Colloidal sols directly formed by mixing substances like gum, gelatine, starch, rubber etc. With a suitable liquid (dispersion medium) are called lyophillic sol. These sols are also called reversible sols.
b)Lyophobic Colloids: -
These words ‘Lyophobic’ means liquid hating substance like metals their sulphides etc. When simply mixed with the dispersion medium do not form the colloidal sol. Their colloidal sols can be prepared by only special methods; such sols are called lyophobic sols. These sols are also called irreversible sols.
Preparation of colliods:
a)Electrical disintegration or Bredig’s Arc Method: -
this process involves dispersion well as condensation. Colloidal sol of metals such as gold silver etc can be prepared by this method. in this method electric arc is struck between electrodes of metal immersed in the dispersion medium the intense heat product vaporized the metal, which then condenses to form particles of colloidal size.
c) Peptization: -
it is defined as the “process of converting a precipitate into colloidal sol” by shaking it with dispersion medium in the presence of a small amount of electrolyte. The electrolyte used for this purpose is called peptizing agent.
During peptization: - the particulate absorbs the one of the ions of the electrolyte on its surface. This cause the development of +ve charge on precipitate, which ultimately break up into small particles of the size of a colloid.
Purification of colloidal Solution: -
The process used for reducing the amount of impurities to a requisite minimum is known as purification of colloidal solution.
it is carried out by following methods
(I) Dialysis: -
It is a process of removing a dissolved substance from a colloidal solution by means of diffusion through a suitable membrane. Since, particles (ions or smaller molecular) in a true solution can pass through an animal membrane (bladder) or parchment paper or colloidal particles. The molecules and ions diffuse through membrane into the outer water and pure colloidal solution to left behind.
(II) Electro dialysis: -
The process of dialysis is quite slow it can be made faster by applying an electric field electrodes are fitted in the compartment. The ions present in the colloidal solution migrate out to the oppositely charge to electrodes.
Properties of colloidal solutions:
(I) Colligative Properties: -
The values of colligative properties (osmotic pressure, lowering in vapor pressure, depression in freezing point, elevation in boiling point) are of small order as compared to values shown by true solution at same concentration.
(II) Colour: -
The colour of the colloidal solution depends on the wavelength of the light scatter by the dispersed particles. The wavelength of light further depends on the size and nature of the particles.
(III) Brownian Movement: -
It may be defined as continuous zigzag movement of the colloidal particles in a colloidal solution is known as Brownian movement.
(Iv) Tyndall effect: -
It is may be defending as the scattering of the light by the colloidal particles present in the colloidal solution.
Application of colloids: -
colloids are widely used in the industrial sector.
Example:-
· Electro precipitation of smoke: -
The smoke, before is comes out from the chimney, is led through a chamber containing plates having a charged opposite to that carried by smoke particles. The particles on coming in contact with these plates lose their charge get precipitated, the particles thus settle down on the floor of the chamber. The precipitator is called Cottrell precipitator.
Purification drinking water: -
alum is added to water (that contain impurities) to coagulate the suspended impurities make water fit for colloidal in nature.
Example: - Argyrol is silver sol is used as an eye lotion.
· Medicines :-
Most of the medicines are colloidal in nature Ex:- Argirol is a silver sol used as an eye lotion.
Colloidal: -
A colloidal is a heterogeneous system in which one substance is dispersed (dispersed phase) as very fine particles in another substance called dispersion medium.
Colloidal particles are larger than simple molecules but smaller enough to remains suspended .their range of diameter is between 1and 1000nm (10-9 to 10-6m).
Classification of collides: -
a) Lyophillic colloids: -
The word ‘lyophillic’ means liquid loving. Colloidal sols directly formed by mixing substances like gum, gelatine, starch, rubber etc. With a suitable liquid (dispersion medium) are called lyophillic sol. These sols are also called reversible sols.
b)Lyophobic Colloids: -
These words ‘Lyophobic’ means liquid hating substance like metals their sulphides etc. When simply mixed with the dispersion medium do not form the colloidal sol. Their colloidal sols can be prepared by only special methods; such sols are called lyophobic sols. These sols are also called irreversible sols.
Preparation of colliods:
a)Electrical disintegration or Bredig’s Arc Method: -
this process involves dispersion well as condensation. Colloidal sol of metals such as gold silver etc can be prepared by this method. in this method electric arc is struck between electrodes of metal immersed in the dispersion medium the intense heat product vaporized the metal, which then condenses to form particles of colloidal size.
c) Peptization: -
it is defined as the “process of converting a precipitate into colloidal sol” by shaking it with dispersion medium in the presence of a small amount of electrolyte. The electrolyte used for this purpose is called peptizing agent.
During peptization: - the particulate absorbs the one of the ions of the electrolyte on its surface. This cause the development of +ve charge on precipitate, which ultimately break up into small particles of the size of a colloid.
Purification of colloidal Solution: -
The process used for reducing the amount of impurities to a requisite minimum is known as purification of colloidal solution.
it is carried out by following methods
(I) Dialysis: -
It is a process of removing a dissolved substance from a colloidal solution by means of diffusion through a suitable membrane. Since, particles (ions or smaller molecular) in a true solution can pass through an animal membrane (bladder) or parchment paper or colloidal particles. The molecules and ions diffuse through membrane into the outer water and pure colloidal solution to left behind.
(II) Electro dialysis: -
The process of dialysis is quite slow it can be made faster by applying an electric field electrodes are fitted in the compartment. The ions present in the colloidal solution migrate out to the oppositely charge to electrodes.
Properties of colloidal solutions:
(I) Colligative Properties: -
The values of colligative properties (osmotic pressure, lowering in vapor pressure, depression in freezing point, elevation in boiling point) are of small order as compared to values shown by true solution at same concentration.
(II) Colour: -
The colour of the colloidal solution depends on the wavelength of the light scatter by the dispersed particles. The wavelength of light further depends on the size and nature of the particles.
(III) Brownian Movement: -
It may be defined as continuous zigzag movement of the colloidal particles in a colloidal solution is known as Brownian movement.
(Iv) Tyndall effect: -
It is may be defending as the scattering of the light by the colloidal particles present in the colloidal solution.
Application of colloids: -
colloids are widely used in the industrial sector.
Example:-
· Electro precipitation of smoke: -
The smoke, before is comes out from the chimney, is led through a chamber containing plates having a charged opposite to that carried by smoke particles. The particles on coming in contact with these plates lose their charge get precipitated, the particles thus settle down on the floor of the chamber. The precipitator is called Cottrell precipitator.
Purification drinking water: -
alum is added to water (that contain impurities) to coagulate the suspended impurities make water fit for colloidal in nature.
Example: - Argyrol is silver sol is used as an eye lotion.
· Medicines :-
Most of the medicines are colloidal in nature Ex:- Argirol is a silver sol used as an eye lotion.
Its simple notes sir.. Tq sir
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