Common salt is behaving as a colloidal particle in benzene as a dispersion medium. It means the solute particles attain a size of the colloidal range of (1-1000 nm). So, we can say that the colloid is not a substance but a state of substance which depends on the particles size.
When the long chain of fatty acids like soap and detergent is added to water the hydrophobic part of their chain is aligned towards the centre in such a manner that they form a spherical shape and their hydrophilic part is facing towards outside. This spherical like structure is known as a micelle.
Structure of sodium soap(Left side - hydrophobic part, Right...
Tyndall effect- When a beam of light is passed through the colloidal solution the colloidal particles scatter the light and make the beam visible in colloidal solution. This effect is observed by Faraday and later on detail in studied by Tyndall and is known as the Tyndall effect.
Dialysis- The process of removing a dissolved substance from the colloidal solution by means of diffusion through a suitable membrane. The principle behind this is small molecules and ions can pass through the animal membrane.
The movement of colloidal particles under the influence of electric current is known as electrophoresis. The negatively charged particles move towards the cathode and positive charge particles move towards the anode.
Shape-selective catalysis, in which the reaction mainly depends on the size of the reactants and product molecules and also the pore structure of the catalyst.
Ex. zeolites are good shape selective catalyst.
Zeolites are good shape selective catalyst due to their honeycomb-like structures. They are alumino-silicates that are microporous in structures. They are the 3D network of silicates in which some atoms of silicon are replaced by aluminium giving framework. Size and shape of reactant and product molecules, as well as pores and cavities of zeolites, are the reaction determining factors in zeolites.
(i)The activity of the catalyst is to increase the rate of a particular reaction. It depends on the strength of chemisorption to a large extent. Adsorption of reactants should be neither too high nor too weak. It should just be optimum so that the catalyst is staying active.
(ii)The selectivity of catalyst is the ability to direct the reaction to give a particular product when under the same...
Four examples of heterogeneous catalysis-
1. oxidation of sulphur dioxide into sulphur trioxide in the presence of Pt.
2. the combination between dinitrogen and dihydrogen to form ammonia
3. Hydrogenation of vegetable oils in the presence of Ni as a catalyst
4. Ostwald Process - oxidation of ammonia into nitric acid in the presence of Pt
The cleansing action of soap is because of emulsification and micelle formation. Soaps are sodium or potassium salts of long chain fatty acids, represented as (e.g. sodium stearate ). when dissolved into the water it dissociates into and ions. . The long carbon chains are non-polar in nature (hydrophobic) and are polar in nature (hydrophilic part).
When the soap is added to dirt containing...
The emulsifying agents are also known as emulsifiers. For stabilisation of emulsion, they form an interfacial film between suspended particles and medium.
Example- for O/W gums, natural and synthetic soaps for W/O heavy salts of fatty acids, long chain alcohols
The colloidal solution in which both the dispersed phase and dispersion medium are liquid in nature are called emulsions.
There are two types of emulsions-
(i) oil in water (O/W) -Oil is dispersed phase and water is dispersion medium (milk)
(ii) water in oil (W/O)- Water is the dispersed phase and oil is dispersion medium (cold cream, butter etc.)