Surface Chemistry
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New answer posted
8 months agoContributor-Level 10
5.22
Colloidal solutions get classified in 8 Types on the basis of physical state of the dispersed phase and dispersion This are given in following table-
Dispersed phase | Dispersion media | Types of colloids | Example |
Solid | Solid Sol | Gem stone | |
Solid | Liquid | sol | Paints, cell fluid. |
Solid | Gas | Aerosol | Dust, smoke. |
Liquid | Solid | Gel | Butter, Cheese. |
Liquid | Emulsion | Milk, Hair cream. | |
Liquid | Gas | Aerosol | Fog, Mist, Cloud. |
Gas | Solid | Solid Sol | Pumice stone. |
Gas | Liquid | Foam | Froth, soap lather. |
2) Depending upon nature of Particles of dispersed phase it can be classified into 3 categories
Multimolecular Colloids-In this colloidal particle consist of aggregates of atoms having diameter less than
Macromolecular colloids-The colloids in which Large particle aggregates and dissolved into suitable
Associated colloids – This colloids show Colloidal property at higher This contains ions of colloidal size.
3) Depending upon interactions between dispersed phase and dispersion medi
New answer posted
8 months agoContributor-Level 10
5.21
Enzymes are complex nitrogenous organic compounds which are produced by Living plants and animals. They are protein molecules of higher molecular masses. They are effective catalysts termed as “biochemical catalysts”
Mechanism of enzyme catalysis- There are number of cavities present on the surface of colloidal particle of enzymes. They have specific shape and contains group like –COOH, -SH, - OH. etc. they are active centers of enzyme particle molecules of reactant which have complimentary shape fit into this cavities, this forms activated complex Which then decompose to yield products. This reaction occur in 2 steps-
Enzyme (
New answer posted
8 months agoContributor-Level 10
5.20
Multimolecular colloids | Macromolecular colloids |
1) formed by aggregation of large number of atoms of smaller radii. | 1) Formed by particles of large size. |
2) Low molecular masses | 2) High molecular masses. |
3) Weak van there waals forces | 3) Strong van there waals Forces |
4) Ex-sols of gold and sulphur. | 4) Ex-Nylon, starch. |
Associated colloids- They formed by aggregation of large number of ions. instead of atoms or molecules in above two colloids. They have van there waals force directly proportional to concentration of ions. Ex- Soap Sol.
New answer posted
8 months agoContributor-Level 10
5.19
Lyophilic - lyophilic (liquid loving) this sols formed by direct mixing of substances like gum starch etc. with suitable liquid, called as lyophilic sols. This are called as reversible sol because if dispersion medium is separated from the dispersed phase it can be reconstructed just by mixing them. These sols are quite stable. Ex-Protein, Starch.
Lyophobic -lyophobic (liquid hating) this sols don't formed by direct mixing of dispersed phase and dispersion media they require special methods for preparation. Ex-Sols of metal sulphides .
This Lyophobic (Hydrophobic-water hating) sols gets easily coagulated because they are less s
New answer posted
8 months agoContributor-Level 10
5.18
Temperature- Adsorption decreases with increase of temperature because it is an exothermic process, by using le chatelier's principle the reaction will proceed in backward direction.
Pressure- Adsorption increase with increase in pressure at constant temperature.
New answer posted
8 months agoContributor-Level 10
5.17
Colloidal solutions get classified in 8 Types on the basis of physical state of the dispersed phase and dispersion medium. This are given in following table-
Dispersed phase | Dispersion media | Types of colloids | Example |
Solid | Solid Sol | Gem stone | |
Solid | Liquid | sol | Paints, cell fluid. |
Solid | Gas | Aerosol | Dust, smoke. |
Liquid | Solid | Gel | Butter, Cheese. |
Liquid | Emulsion | Milk, Hair cream. | |
Liquid | Gas | Aerosol | Fog, Mist, Cloud. |
Gas | Solid | Solid Sol | Pumice stone. |
Gas | Liquid | Foam | Froth, soap lather. |
New answer posted
8 months agoContributor-Level 10
5.16
When adsorbate (gas or liquid mostly) absorbed then their entropy get reduced i.e. ΔS is negative. For every spontaneous process ΔG must be negative. ΔG = ΔH - TΔS, as TΔS is positive (ΔS is negative) ΔH must be negative in order to make ΔG negative. Hence ΔH is negative that means the reaction is exothermic. Hence every adsorption reactions are exothermic.
New answer posted
8 months agoContributor-Level 10
5.15
Adsorption of reactants on the solid surface of the catalysts increases the rate of reaction. Generally, the reactant is gas whereas catalyst is solid. Reactant molecules get adsorbed on the surface of the catalyst as a result concentration of reactant increases leads to increase in the rate of reaction.
There are many important reactions is based on this, for Ex (1) manufacturing of ammonia using iron as a catalyst,
2. manufacture of H2SO4 By contact process,
3. use of finely divided Nickel in the hydrogenation of cells
New answer posted
8 months agoContributor-Level 10
5.14
Increasing the adsorbing power of adsorbent is known as activation of adsorbent.it can be achieved by
Increase in surface area of
By dividing the adsorbent into small
By making its surface
New answer posted
8 months agoContributor-Level 10
5.13
Adsorption Isotherm- The variation in the amount of a gas adsorbed by the adsorbent with pressure at constant temperature can be expressed by the curve . This curve is known as 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.
x/m = k P1/nm
Where x is the mass of gas adsorbed on mass m of the adsorbent pressure P. k and n are constants depend on nature of adsorbent. This relationship is expressed in the form of curves where the mass of the gas adsorbed per gram of adsorbent is pl
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