Assertion (A) Coagulation power of $\mathrm{Al}^{3+}$ is more than $\mathrm{Na}^{+}$.
Reason (R) Greater the valency of the flocculating ion added, greater is its power to cause precipitation (Hardy-Schulze rule).
Assertion (A) Detergents with low CMC are more economical to use.
Reason (R) Cleansing action of detergents involves the formation of micelles. These are formed when the concentration of detergents becomes equal to CMC.
What is the role of adsorption in heterogeneous catalysis?
Catalyst is used to increase rate of reaction. Heterogeneous catalyst is used to increase rate of reaction in which catalyst is not in phase with reactants and products.
Role of adsorption in heterogeneous catalysis are
(i) Diffusion of reactants to the surface of the catalyst.
(ii) Reactants are adsorbed on the catalyst surface.
(iii) Occurrence of chemical reaction at catalyst surface.
(iv) Desorption.
(v) Diffusion of reaction products away from the catalysts surface.
e.g.,
What are the applications of adsorption in chemical analysis?
There are various applications of adsorption in chemical analysis.
Some of which are as follows
(i) In thin layer chromatography The lower adsorbing particles comes out readily while another having higher adsorbing tendency comes out later. On this basis compounds are separated or analysed.
(ii) In adsorption indicators Surface of certain precipitate has an ability to adsorb some dyes to produce a characteristic colour e.g., AgX adsorbs eosin dye and thereby producing a characteristic colour at the end point.
(iii) In qualitative analysis Specific material has specific adsorption tendency so particular ion can be identified very easily.
(iv) In the separation of inert gases Different inert gases are adsorbed to different extents at different temperatures on coconut charcoal. This forms the basis of their separation from a mixture.
What is the role of adsorption in froth floatation process used especially for concentration of sulphide ores?
In froth floatation process sulphide ore is shaken with pine oil and water, the ore particles are adsorbed on froth that floats and the gangue particles settle down in tank. Thus, role of adsorption in froth floatation process can be understood as following processes.
(i) Adsorption of pine oil on sulphide ore particles.
(ii) Formation of emulsion takes place.
(iii) Froth is formed along with ore particles.
(iv) Mechanism of the functioning of shape selective catalysis.
As sulphide are extracted using froth floatation method therefore, only sulphide ore particles will show these type of adsorbing tendency.