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(i) when a beam of light is passed the scattering of light is observed, which is known as Tyndall effect. The colloidal particles size, which is in the range of wavelength of light scatters them in all directions.
On the basis of the nature of the interaction between the dispersed phase and dispersion medium the colloids are divided into two categories; (i)lyophilic sols(water-loving) and (ii)lyophobic sols (water repelling)
Depending upon the type of particles of the dispersed phase, colloids are categories into- Multimolecular colloids Macro-molecular colloids Associated  colloids  
There are eight types of colloids whether the components are solid, liquids or gas. Here components mean dispersed phase and a dispersion medium.
Enzymes are that substance which is produced by living plants and animals. These are the complex nitrogenous organic compound. Actually, it is a protein molecule of high molecular weight and forms colloidal solution on dissolving in water. Brief mechanism of enzyme catalysis- On the surface of enzymes, active centres are present of different shape and size and possess active groups like  etc....
Multimolecular colloids- On dissolution, a large number of atoms or smaller molecules aggregate together to form species of size 1-1000 nm of colloidal range. This species termed as multimolecular collides. Example- gold sol and sulphur sol. Macro-molecular colloids-  In suitable solvents, they form solutions in which the size of the macromolecules may or may not be in the colloidal range. Such...
(i)Lyophilic sols- These sols are solvent loving. In these types of sols, the dispersed phase has an affinity towards the dispersion medium(liquid).example- starch, gum and protein. The affinity is due to the ability to form a hydrogen bond with the dispersion medium(water) These sols are reversible in nature. (ii)Lyophobic sols- These are water-hating. In these types of sols, the dispersed...
Effect of temperature and pressure on the adsorption of gases on solids- Temperature- According to Le-Chatelier’s principle the physical adsorption readily occurs at low temperature and adsorption rate is slow at high temperature. Pressure-  As we increase the pressure the amount of gas adsorbed on adsorbent is increased as the volume of gas decreases. Since it is an exothermic process, the...
First criteria for classifying the colloids is the physical state of the dispersed phase and a dispersion medium. Depending upon whether the dispersed phase and the dispersion medium are solids, liquids or gases, there are eight types of colloidal systems -
Adsorption is always exothermic because- During adsorption, the residual forces of the surface always decrease. As a result, there is a decrease in surface energy, which emits as a heat.  Of adsorption is always negative. The freedom of movement of adsorbate (gas) molecule becomes restricted when the adsorbent adsorbs the adsorbate(gas). As a result, the entropy decreases ( is negative). For...
Those catalytic process in which the reactant and catalyst are in a different phase is known as heterogeneous catalysis.  Role of adsorption in heterogeneous catalysis- Diffusion of reactants to the surface of the catalyst. Adsorption of reactant is on the surface of the catalyst. The chemical reaction can occur at the catalyst surface by intermediate formation between them. Desorption of the...
by activation of adsorbent, it means increasing the adsorbing power of adsorbent. We can do it by following ways- By increasing the surface area of the adsorbent by cutting adsorbent into small pieces or powdering it. Some treatment can be also done to the adsorbent so that its power gets increased. example- charcoal is activated by heating it between 650 K and 1330 K in vacuum or air  
The adsorption isotherm is a relation curve between the variation in the amount of gas adsorbed by the adsorbent with pressure at a constant temperature. Fig:- Adsorption isotherm Freundlich adsorption isotherm- Freundlich gave an empirical relationship between the quantity of gas adsorbed by a unit mass of solid (adsorbent) and pressure (at a particular temperature). At high pressure-   ...
The factors which influence the adsorption of a gas on a solid- Surface area-the greater the surface area of the adsorbent higher is the amount of adsorbent to get absorbed. temperature- Adsorption is an exothermic process. So, physical adsorption readily at a lower temperature and decrease with increase in temperature. Pressure- On increasing pressure, the amount of adsorbate increased as the...
We know that adsorption is a surface phenomenon. The extent of adsorption depends on the surface area. So, Adsorption is directly proportional to the surface area of the adsorbent. More the surface area more is the amount of adsorbent adsorbed. So, therefore finely divided substance is more effective as an adsorbent due to its high surface area. 
Difference between physisorption and Chemisorption- Physisorption Chemisorption 1. Happens due to van der Waal forces. 2. It's not specific in nature and reversible in nature. 3. It depends on the nature of the gas. More liquefiable gas is adsorbed easily. 4. enthalpy of adsorption is low around 20-40 kJ/mol 5. Low temperature required 6. It depends on the surface area. Higher the area...
Adsorption- It is a surface phenomenon in which the molecules or substances accumulate at the surface rather than in a bulk of a solid or liquid. The substance that gets adsorbed is called adsorbate and the material on which it is adsorbed is called adsorbent. In adsorption, the adsorbate does not penetrate the adsorbent surface it concentrates only at the surface of the solid and liquid....
The precipitate is formed from reactions so it contains some chemical or unwanted substances traces (like impurities, catalyst and reactant). For quantitative estimation of the product, we need to remove these additional substances which get adsorbed onto the surface of the required product and it gives us the wrong information about the product of the reaction. So to avoid this problem we wash...
According to Hardy-Schulze law that ‘the higher the valence of the flocculating ion added, the higher is its power to cause precipitation. Here he does not about the size of the ion, which polarises the other oppositely charged ion. Hence the modified law should be  "the greater the polarising power of flocculating ion added, the greater is its power to cause precipitation."
In catalytic reaction, the reactant attached on the surface of the catalyst and form complex and after some procedure, it becomes the product of the reaction. We need to detach it from the surface of the catalyst to get the product and catalyst separately and hereby desorption process, we can get the product.
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