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Industrial Application of Adsorption Process 1. Activated charcoal is used to remove bad odours inside refrigerator and to deodourise tap water in water purifier. It is also used in gas masks to adsorb poisonous gases in the atmosphere. 2. In sugar industry animal charcoal is used to decolourise raw sugar solution obtained from sugar cane. 3. In chromatography, suitable adsorbents are used. They selectively adsorb certain substance from solution. Adsorption chromatography is used for detection and separation of mixtures. 4. In dehumidifier, silica gel is used as adsorbent. 5. Activated charcoal is  used to maintain vacuum in laboratory vessels such as Dewar flask. 6. Heterogeneous catalysis  mostly operate through adsorption of reactant molecules. 7. Softening of water using ion exchange resin is based on selective adsorption of ions which cause hardness. 8. In mordant dyeing, mordants adsorb colour. 9. Ferric hydroxide can adsorb arsenic ions and hence i...

Adsorption Isobar : Effect of temperature Most of the adsorptions are exothermic reactions, Hence adsorption generally depend on temperature. Exothermic reactions are mostly spontaneous at low temperature. Hence the extent of adsorption decreases with increase of temperature at constant pressure. A plot of extent of adsorption verses temperature at constant pressure is known as adsorption Isobar.

Factors affecting adsorption: Pressure of Gas Adsorption and desorption are reversible process and take place simultaneously leading to equilibrium state. Adsorbent + gas  <========> Adsorbent gas In the forward direction, during adsorption, volume decreases since gases are adsorbed to the surface. Hence applying Le-Chatelier principle, we can predict effect of pressure. At high pressure, the system has a tendency to decrease volume and shifts towards forward direction, ie , more adsorption take place. Now we can conclude that extent of adsorption (x/m) increases with increase in pressure. Where x= number of the moles of gas adsorbed and m = mass of adsorbent, at equilibrium. Variation of  x/m with pressure can be experimentally studied and can be plotted as a graph at constant temperature. Such graphs obtained by plotting (x/m) against (p) at constant temperature are called, adsorption isotherm . To see all Factors affecting adsorption of gases on...

Specific area of adsorbent affects adsorption of gases on solids The surface area of an adsorbent available for adsorption is known as specific area of adsorbent. Depending on the nature of surface, impurity at the surface etc, specific area of adsorbent changes. Rough surface can adsorb more, due to greater available surface area. Similarly solids can adsorb more when powdered. When powdered, surface area increases. Hence porous and finely divide forms of adsorbent have greater adsorption power. Activation of adsorbent We can increase the activity of an adsorbent using different methods. Cleaning surface, making rough surface, powdering etc are some of these method. To see all Factors affecting adsorption of gases on solids visit http://entrancechemistry.blogspot.com/2012/11/factors-affecting-adsorption-of-gases.html

Important Factors affecting adsorption of gases are 1. Nature of gas. 2. Nature of adsorbent. 3. Specific area of adsorbent. 4. Activation of the adsorbent. 5. Pressure of the gas. 6. Temperature 1. Nature of gas Adsorption can be either physisorption or chemisorption . Chemical adsorption is highly specific, hence only a particular adsorbent can adsorb a gas. For example, Nitrogen is adsorbed by Iron. Adsorption of hydrogen by nickel or platinum. But physisorption is not specific. In such cases it is observed that easily liquefiable gases are more adsorbed than permanent gases like He, N 2 , O 2 , H 2 etc. It is due to the reason that HCl, SO 2 , CH 4 , NH 3 , SO 3 etc are more adsorbed. In case of easily liquefiable gases, van der Waals  force or molecular forces are more predominant, and hence physisorption becomes more significant. 2. Nature of adsorbent The extent of adsorption depends on nature of the adsorbent. Charcoal and silica gel are good adsorben...

Physisorption and Chemisorption definition In adsorbed state the adsorbate is held on the surface of adsorbent by attractive forces (bond). Depending on the nature of attractive forces, adsorption can be of two types - physical adsorption (Physisorption) and chemical adsorption (Chemisorption) . In chemisorption there is a strong chemical bond. During adsorption, a new bond is formed between adsorbent and adsorbate. Therefore adsorptions are generally exothermic (▵H = -ve). But entropy and free energy decreases during adsorption. Enthalpy change during adsorption process are called enthalpy of adsorption . It is defined as the heat evolved at constant pressure, when one mole of an adsorbate is adsorbed on the surface of adsorbent. For physical adsorption and chemical adsorption , its values ranges in the order of -20KJ/mol and 200kjmol -1 . Difference between physisorption and chemisorption are given below. Comparison Between Physisorption and Chemisorption ...

Definition of Micelles (Associated colloids) There are some substances which at low concentrations behave as normal strong electrolytes but at higher concentrations exhibit colloidal behavior due to the formation of aggregated particles. These associated particles are called micelles or associated colloids . The formation of micelles take place only above a particular temperature called Kraft temperature (T K ) and above a particular concentration called critical micelle concentration (CMC). Example: Detergents and soaps. Soap is sodium salt of higher fatty acid like C 17 H 35 COONa (sodium stearate). In aqueous solution soap ionizes as The RCOO - ions (C 17 H 35 COO - ) and Na + ions. C 17 H 35 COONa ---------> C 17 H 35 COO - + Na + The RCOO - ions however consist of two parts. That is, long hydrocarbon chain R(-C 17 H 35 ) also called non-polar tail which is hydrophobic and the polar group COO - called polar-ionic head which is hydrophilic. In concentrated solution,...

Depending upon the nature of interaction between the dispersed phase and the dispersion medium, colloids are classified in to the lyophilic colloids (solvent attracting) and lyophobic colloids (solvent repelling). If water is the dispersion medium, it is called as hydrophilic and hydrophobic colloid respectively. Lyophilic colloids The meaning of the word 'lyophilic' is 'liquid-loving' or 'solvent attracting'. That means, these are colloids in which there is strong interaction between the two phases. Lyophilic colloids are those dispersions in which the dispersed phase exhibits a definite affinity for the medium and as a results extensive solvation of the colloidal particles takes place. They are directly formed by mixing the two phases.Eg :- Gum, soap, starch, gelatin, rubber etc. These sols are also called reversible sols. Because, if the dispersion medium is separated from the dispersed phase, the sol can be reconstituted by simply mixing with the dispersion...

The enzymes are acting as catalysts due to the presence of certain specific regions on their surface, called active sites or catalytic sites. Two models have been proposed for enzyme action. Lock and Key model The active site of a given enzyme is so shaped that only its specific substrates fit into it. We can compare substrate or reactant molecule to the key and active site to the lock. Induced-fit model Modern X-ray crystallographic and spectroscopic methods show that in many cases the enzyme changes shape when the substrate lands at the active site. This induced fit model of enzyme action pictures the substrate inducing the active site to adopt a perfect fit, rather than a rigidly shaped lock and key. We can explain the mechanism of enzyme action using the transition state theory or the intermediate compound formation theory. It involves the following steps. 1) The reactant molecules bind to a region on the surface of the enzyme called active site which results in the formation of...