Solution:- (i) When a beam of light is transmitted through a colloidal solution, light scattering is detected. This phenomenon is called the Tyndall effect. The path of the beam is...
Explain what is observed when
Define emulsions. What are their different types? Give examples of each type.
The colloidal solution in which both the dispersed phase and the dispersion medium are liquids is known as an emulsion. Emulsions are divided into two categories: (a) Oil in water type: The...
Comment on the statement that “colloid is not a substance but a state of substance”.
In a benzene medium, common salt which is a typical crystalloid in an aqueous medium acts as a colloid. As a result, we can claim that colloidal substances do not belong to a distinct class of...
Explain the terms with suitable examples:
(i) Alcosol
(ii) Aerosol
(iii) Hydrosol
Solution : (ii) Alcosol: An alcosol is a colloidal solution in which the dispersed phase is a solid substance and the dispersion medium is alcohol. For example, a colloidal sol of cellulose nitrate...
What are micelles? Give an example of a micellar system.
Micelle is formed when soaps and detergents are dissolved in water. Micelle consists of hydrophobic and hydrophilic parts. When present in water, they form spherical formations with their...
Give four uses of emulsions.
Emulsions are used for a variety of purposes. Four uses of emulsions have been listed below: (i) The cleansing action of soap is determined by the formation of emulsions. (ii) The emulsification...
Explain the following terms:
(ii) Coagulation
(iii) Dialysis
(iv)Tyndall effect
Solution: (i) Electrophoresis: It is the process of causing colloidal particles to move randomly in response to an applied electric field. The anode attracts negatively charged...
What is shape-selective catalysis?
Shape-selective catalysis is a catalytic reaction that depends on the product molecules, the size of the reactants, and the pore structure and size of the catalyst. For example, a catalytic process...
Describe some features of catalysis by zeolites.
Some features of catalysis by zeolites are listed below:- (i) Zeolites are alumino-silicates that are naturally microporous. (ii) Because of their honeycomb-like structure, zeolites are...
What do you mean by activity and selectivity of catalysts?
a) Activity: The ability of a catalyst to enhance the rate of a reaction is referred to as its activity. The main factor, chemisorption, determines a catalyst's activity. The process should be...
Give four examples of heterogeneous catalysis.
(i) Sulphur trioxide is generated when sulphur dioxide is oxidised. Pt acts as a catalyst in this process. 2SO2(g) → Pt(s) + 2SO3(g) (ii) Ammonia is formed when dinitrogen and dihydrogen are...
The action of soap is due to emulsification and micelle formation. Justify.
The cleansing activity of soap is determined by emulsification and micelle production. The basic combination of soap contains sodium and potassium salts of long-chain fatty acids (R-COO-Na+). The...
How do emulsifiers stabilize emulsion? Name two emulsifiers.
Emulsifiers stabilise an emulsion by lowering the interfacial tension between the two liquids that make up the emulsion. Emulsifiers are long-chain compounds having polar groups. For instance,...
How are colloids classified on the basis of – (i) physical states of components (ii) nature of dispersed phase and (iii) interaction between the dispersed phase and dispersion medium?
Colloids are classified in a variety of ways : (I) The dispersed phase and dispersion medium, or the physical state of the components, are referred to as components. As a result, depending on...
Define enzymes. Briefly describe the mechanism of enzyme catalysis.
Enzymes are large protein molecules with a high molecular mass. When they are dissolved in water, colloidal solutions are created. Living plants and animals manufacture these complex nitrogenous...
Write the differences between multimolecular and macromolecular colloids. Give one example of each. How are associated colloids different from these colloids.
(I) The colloidal particles in multi-molecular colloids are an assemblage of atoms or tiny molecules having a diameter of less than 1 nm. The molecules in the aggregate are held together by Van der...
Define lyophilic and lyophobic sols. Give one example of each type. Why are hydrophobic sols easily coagulated?
Lyophilic sols - Lyophilic sols are colloidal sols made by combining ingredients like gum, gelatin, starch, and others in a liquid called the dispersion medium. These sols are reversible in nature....
How do pressure and temperature affect the adsorption of gases on solids?
Effect of pressure : Because adsorption is a reversible process that is accompanied by a decrease in pressure, adsorption increases as pressure rises. Effect of temperature : According to...
Write the classification of colloidal solutions on the basis of physical states of the dispersed phase and dispersion medium.
Colloidal solutions can be classified as follows on the basis of their dispersed phase and dispersion medium : Dispersed phase Dispersion medium Type of colloid Example 1. Solid Solid Solid Sol...
Why is adsorption an exothermic process?
The process of adsorption is always exothermic. There are two ways to understand this which are as follows :- (I) The residual forces on the adsorbent's surface are reduced as a result of...
What is the role of adsorption in heterogeneous catalysis?
Heterogeneous catalysis is a catalytic process in which the catalyst and reactants are present in different phases. This form of heterogeneous catalytic action is explained by the adsorption theory....
What is the activation of adsorbent? How is it achieved?
Activation of adsorbent is the process of increasing the adsorption power of the adsorbent. The following methods are used to activate adsorbents: (I) Increasing the adsorbent surface area. This can...
What is an adsorption isotherm? Describe Freundlich’s adsorption isotherm.
The plot of the amount of adsorption (x/m) against the pressure of the gas (P) at constant temperature is known as the adsorption isotherm (T). Three cases arise from the graph which are as follow...
Write the factors influencing the adsorption of a gas on a solid.
Factors influencing the adsorption of gas on a solid:- (1) Nature of the gas : Easily liquefiable gases, such as NH3, HCl, etc., have strong Van der Waal forces, so they are adsorbed to a greater...
Why is a finely divided substance more effective as an adsorbent?
Because adsorption is a surface phenomenon, it is directly proportional to the surface area. Due to its large surface area, a finely split material acts as a good adsorbent. With an increase in...
Write at least 5 differences between physisorption and chemisorption.
Physisorption Chemisorption The adsorbate attaches to the surface of the adsorbent by weak van der Waal’s forces of attraction. The adsorbate...
Write the difference between absorption and adsorption illustrating using one example of each.
Absorption is the phenomenon of uniform distribution of a substance throughout the bulk of the solid and liquid. It is a bulk phenomenon. For example, absorption of water into the bulk of a sponge....