Question:

Distinguish between the meaning of the terms adsorption and absorption. Give one example of each.

Answer:

Step 1: Adsorption is the process of a material sticking to the surface of another material. An example of adsorption is the way water droplets stick to the surface of a leaf.

Step 2: Absorption is the process of a material taking in another material. An example of absorption is a sponge taking in water.

Question:

Discuss the effect of pressure and temperature on the adsorption of gases on solids.

Answer:

1. Start by defining the terms “pressure” and “temperature” and explaining how they are related.

2. Explain how pressure and temperature affect the adsorption of gases on solids. For example, an increase in temperature can cause an increase in the rate of adsorption, while an increase in pressure can cause a decrease in the rate of adsorption.

3. Provide examples of how pressure and temperature can affect the adsorption of gases on solids. For example, a decrease in temperature can cause a decrease in the rate of adsorption, while an increase in pressure can cause an increase in the rate of adsorption.

4. Discuss the implications of pressure and temperature on the adsorption of gases on solids. For example, an increase in the rate of adsorption can lead to an increase in the amount of gas that is adsorbed, while a decrease in the rate of adsorption can lead to a decrease in the amount of gas that is adsorbed.

5. Summarize the key points of the discussion, such as the effects of pressure and temperature on the adsorption of gases on solids.

Question:

How are colloids classified on the basis of: (i) physical states of components, (ii) nature of dispersed phase and (iii) interaction between dispersed phase and dispersion medium

Answer:

(i) Physical states of components: Colloids can be classified based on the physical states of the components as either solid colloids, liquid colloids, or gas colloids.

(ii) Nature of dispersed phase: Colloids can be classified based on the nature of the dispersed phase as either lyophilic colloids, lyophobic colloids, or mixed colloids.

(iii) Interaction between dispersed phase and dispersion medium: Colloids can be classified based on the interaction between the dispersed phase and the dispersion medium as either electrostatic colloids, steric colloids, or mixed colloids.

Question:

What is shape selective catalysis?

Answer:

1. Shape selective catalysis is a type of catalysis that relies on the shape of the catalyst to selectively promote certain reactions over others.

2. Shape selective catalysis works by having the catalyst interact with the reactants in a specific way that favors the desired reaction. For example, the shape of the catalyst may allow it to interact with one reactant in a way that makes it more likely to react with another reactant, while inhibiting the reaction of other reactants.

3. This type of catalysis is important in many industrial processes, such as the production of pharmaceuticals, plastics, and other materials. It can also be used to increase the efficiency of chemical reactions and reduce the amount of energy required for a reaction.

Question:

Why is adsorption always exothermic?

Answer:

1. Adsorption is a process in which molecules from a gas, liquid, or dissolved solid are attracted and held on the surface of a solid or liquid.

2. During the adsorption process, energy is released in the form of heat, making it an exothermic reaction.

3. This is due to the fact that when molecules are attracted to the surface of a solid or liquid, the attractive forces between them become stronger than the attractive forces between them in the gas, liquid, or dissolved solid phase, resulting in the release of energy.

4. Therefore, adsorption is always exothermic because energy is released in the form of heat.

Question:

What are enzymes ? Write in brief the mechanism of enzyme catalysis

Answer:

Enzymes are proteins that act as catalysts in biochemical reactions. They speed up the rate of a reaction without being consumed in the process. Enzyme catalysis involves the formation of an enzyme-substrate complex, where the enzyme binds to the substrate and alters its shape in order to create an active site. The active site is where the substrate binds and the enzyme catalyzes the reaction. The enzyme then releases the product(s) of the reaction and the enzyme-substrate complex dissociates.

Question:

What are emulsions? What are their different types? Give examples of each type.

Answer:

Answer:

1. Emulsions are mixtures of two or more liquids that are normally immiscible (unable to mix).

2. The different types of emulsions are oil-in-water emulsions and water-in-oil emulsions.

3. Examples of oil-in-water emulsions include mayonnaise, vinaigrette, and milk.

4. Examples of water-in-oil emulsions include butter, margarine, and cream.

Question:

What is the difference between multimolecular and macromolecular colloids? Give one example of each. How are associated colloids different from these two types of colloids?

Answer:

1. Multimolecular colloids are composed of small molecules that are suspended in a medium, while macromolecular colloids are composed of large molecules, such as polymers, that are suspended in a medium. An example of a multimolecular colloid is a fog, while an example of a macromolecular colloid is a gel.

2. Associated colloids are composed of large molecules that are associated with one another, rather than suspended in a medium. An example of an associated colloid is a solution of proteins.

Question:

Describe some features of catalysis by zeolites.

Answer:

1. Zeolites are porous materials composed of alumino-silicates that are used as catalysts in a wide variety of chemical reactions.

2. Zeolites are highly selective catalysts, meaning that they can promote specific reactions without affecting other reactions.

3. Zeolites have a large surface area, which allows them to interact with a large number of reactants and products.

4. Zeolites can act as both an acid and a base catalyst, depending on the reaction.

5. Zeolites can be used to increase the rate of a reaction, reduce the amount of energy required for a reaction, and increase the yield of a reaction.

6. Zeolites can be used in a variety of industrial processes, such as petrochemical refining, pharmaceutical manufacturing, and food processing.

Question:

Action of soap is due to emulsification and micelle formation. Comment.

Answer:

1. Emulsification is the process of combining two or more liquids that usually don’t mix together, such as oil and water. Soap molecules contain a hydrophilic (water-loving) head and a hydrophobic (water-hating) tail. When soap is added to water, the hydrophilic heads of the soap molecules orient themselves towards the water molecules, while the hydrophobic tails orient themselves away from the water molecules. This creates a kind of bridge between the oil and water molecules, allowing them to mix together.

2. Micelle formation occurs when soap molecules aggregate in water to form tiny clusters called micelles. The hydrophilic heads of the soap molecules orient themselves towards the water molecules, while the hydrophobic tails orient themselves away from the water molecules. This creates a kind of cage around the oil molecules, allowing them to be suspended in the water. The micelles also help to break down the surface tension of the water, making it easier for oil and water to mix together.

3. In summary, the action of soap is due to the combination of emulsification and micelle formation. The emulsification process creates a bridge between the oil and water molecules, allowing them to mix together. The micelle formation creates a cage around the oil molecules, allowing them to be suspended in the water. Together, these two processes enable soap to effectively mix oil and water.

Question:

Comment on the statement that ‘Colloid is not a substance but a state of substance’.

Answer:

1. A colloid is a mixture of two or more substances that are dispersed in each other but do not dissolve. The particles of the dispersed substance are larger than those of a true solution, but small enough to remain suspended in the medium.

2. Colloids are not considered a substance because they are not composed of a single type of molecule. Instead, they are a mixture of molecules that are suspended in a medium.

3. Therefore, it is accurate to say that colloid is not a substance but a state of substance, as it is not a single type of molecule but a mixture of molecules suspended in a medium.

Question:

What role does adsorption play in heterogeneous catalysis?

Answer:

1. Adsorption is a process in which molecules from a gas, liquid, or dissolved solid adhere to a surface.

2. In heterogeneous catalysis, adsorption plays an important role in the reaction mechanism by providing a surface for the reactants to bind to.

3. The adsorption of the reactants to the surface of the catalyst lowers the energy barrier of the reaction, allowing it to occur more easily.

4. Additionally, adsorption can alter the structure of the reactants and the catalyst, making them more reactive and increasing the rate of the reaction.

Question:

What do you understand by activation of adsorbent? How is it achieved?

Answer:

Answer: Activation of adsorbent is a process of preparing the adsorbent material for use by increasing its surface area and making it more porous. This is achieved by heating the adsorbent material in an inert atmosphere at a high temperature, typically in the range of 400°C to 900°C. The heat causes the adsorbent material to expand, increasing its surface area and making it more porous. This allows the adsorbent material to absorb more of the desired material from the feedstock.

Question:

What is the difference between physisorption and chemisorption?

Answer:

Step 1: Understand the definition of physisorption and chemisorption.

Physisorption is the physical adsorption of molecules onto the surface of a solid due to weak Van der Waals forces. Chemisorption is the chemical adsorption of molecules onto the surface of a solid due to strong covalent bonds.

Step 2: Compare the two processes.

The main difference between physisorption and chemisorption is the type of bonding that occurs. Physisorption involves weak Van der Waals forces, while chemisorption involves strong covalent bonds. Physisorption is a reversible process, while chemisorption is an irreversible process. Additionally, physisorption is typically a faster process than chemisorption.

Question:

Give reason why a finely divided substance is more effective as an adsorbent.

Answer:

1. A finely divided substance has a large surface area relative to its mass.

2. This increased surface area provides more sites for adsorption to occur.

3. Adsorption occurs when molecules of the adsorbate (the substance being adsorbed) become attached to the surface of the adsorbent (the substance doing the adsorbing).

4. Therefore, a finely divided substance is more effective as an adsorbent because it has more sites for adsorption to occur, allowing for more molecules of the adsorbate to be adsorbed.

Question:

What are lyophilic and lyophobic sols? Give one example of each type. Why are hydrophobic sols easily coagulated?

Answer:

Answer: Lyophilic sols are colloidal solutions in which the particles are attracted to the liquid. Examples of lyophilic sols include gum arabic and gelatin.

Lyophobic sols are colloidal solutions in which the particles are repelled by the liquid. Examples of lyophobic sols include metal hydroxides and sulphides.

Hydrophobic sols are easily coagulated because their particles are not attracted to the liquid, so they can form aggregates which are large enough to settle out of the solution.

Question:

Give four examples of heterogeneous catalysis.

Answer:

1. Using a metal catalyst, such as palladium, to promote the hydrogenation of an alkene.
2. Using an acid catalyst, such as sulfuric acid, to promote the esterification of an alcohol.
3. Using a base catalyst, such as sodium hydroxide, to promote the dehydration of an alcohol.
4. Using a solid catalyst, such as zeolite, to promote the cracking of a hydrocarbon.

Question:

What do you mean by activity and selectivity of catalysts?

Answer:

1. Activity of a catalyst is a measure of how quickly it can cause a chemical reaction to occur.

2. Selectivity of a catalyst is the ability of the catalyst to promote a specific reaction out of a range of possible reactions. It is a measure of the catalyst’s ability to control the outcome of a reaction.

Question:

What is an adsorption isotherm? Describe Freundlich adsorption isotherm?

Answer:

An adsorption isotherm is a graph that plots the amount of a substance adsorbed onto a surface against the concentration of that substance in the surrounding environment. It is used to measure the adsorption capacity of a material.

The Freundlich adsorption isotherm is a mathematical equation that describes the adsorption of molecules onto a surface. It is based on the idea that molecules that have a higher affinity for the surface will be adsorbed more strongly than those with a lower affinity. The equation takes the form of: q = kCⁿ, where q is the amount of adsorbed material, k is the adsorption capacity, and n is the adsorption intensity.

Question:

Explain what is observed when: (i) a beam of light is passed through a colloidal sol. (ii) an electrolyte, NaCl is added to hydrated ferric oxide sol. (iii) electric current is passed through a colloidal sol.

Answer:

(i) When a beam of light is passed through a colloidal sol, the light will be scattered in all directions. This is known as the Tyndall effect, which is caused by the particles in the colloidal sol reflecting and scattering the light.

(ii) When an electrolyte, NaCl is added to a hydrated ferric oxide sol, the hydrated ferric oxide particles will become charged and form a precipitate. This is known as the flocculation process.

(iii) When electric current is passed through a colloidal sol, the particles in the sol will become charged and form a precipitate. This is known as the electrophoresis process.

Question:

How are the colloidal solutions classified on the basis of physical states of the dispersed phase and dispersion medium?

Answer:

1. Colloidal solutions are mixtures of two substances, a dispersed phase and a dispersion medium.

2. The dispersed phase is typically a solid, liquid, or gas, while the dispersion medium is usually a liquid or gas.

3. Colloidal solutions are classified according to the physical states of the dispersed phase and dispersion medium.

4. Solutions with a solid dispersed phase and a liquid dispersion medium are called solid-in-liquid solutions.

5. Solutions with a liquid dispersed phase and a liquid dispersion medium are called liquid-in-liquid solutions.

6. Solutions with a gas dispersed phase and a liquid dispersion medium are called gas-in-liquid solutions.

7. Solutions with a solid dispersed phase and a gas dispersion medium are called solid-in-gas solutions.

8. Solutions with a liquid dispersed phase and a gas dispersion medium are called liquid-in-gas solutions.

9. Solutions with a gas dispersed phase and a gas dispersion medium are called gas-in-gas solutions.

Question:

How do emulsifying agents stabilise the emulsion?

Answer:

1. An emulsifying agent is a substance that helps to form or stabilize an emulsion.

2. An emulsion is a mixture of two or more liquids that are normally immiscible, or unable to be mixed.

3. Emulsifying agents work by coating the droplets of one liquid in the emulsion with a thin layer of molecules. This layer helps to keep the droplets from coming back together and re-forming the original immiscible liquids.

4. The molecules of the emulsifying agent also help to repel the droplets from each other, which keeps the emulsion from breaking down.

5. In this way, emulsifying agents help to stabilise the emulsion and prevent it from separating into its original immiscible components.

Question:

Give four uses of emulsions.

Answer:

1. Emulsions are commonly used in food products such as mayonnaise and salad dressings.

2. Emulsions are used in cosmetics and personal care products such as lotions, creams, and makeup.

3. Emulsions are used as lubricants in industrial applications such as machine tools.

4. Emulsions are used in printing inks and paints to improve the consistency and stability of the product.

Question:

Explain the terms with suitable examples: (i) Alcosol (ii) Aerosol (iii) Hydrosol

Answer:

(i) Alcosol: An alcosol is a solution that contains alcohol, such as rubbing alcohol. Examples include hand sanitizer, mouthwash, and antiseptic wipes.

(ii) Aerosol: An aerosol is a suspension of fine particles in a gas. Examples include hairspray, bug spray, and air fresheners.

(iii) Hydrosol: A hydrosol is a solution that contains water, such as a saline solution. Examples include saline nasal sprays, contact lens solution, and eye drops.

Question:

Explain the following terms: (i) Electrophoresis (ii) Coagulation (iii) Dialysis (iv) Tyndall effect

Answer:

(i) Electrophoresis: Electrophoresis is a laboratory technique used to separate charged molecules, such as proteins, based on their size and charge. It involves the application of an electric field to a mixture of molecules suspended in a liquid, causing them to move through the liquid at different speeds.

(ii) Coagulation: Coagulation is a process in which particles in a liquid are clumped together to form a solid mass. It is commonly used to remove impurities from water or to form a solid mass from a liquid solution.

(iii) Dialysis: Dialysis is a process that uses a semipermeable membrane to separate molecules based on their size and charge. It is commonly used to remove toxins from the blood or to separate proteins from other molecules.

(iv) Tyndall effect: The Tyndall effect is the scattering of light by particles suspended in a liquid or gas. It is most commonly observed when a beam of light is shone through a colloidal solution, causing the particles to become visible.

Question:

What are micelles? Give an example of a micellers system.

Answer:

1. Micelles are small spherical structures composed of lipids and proteins that form in aqueous solutions.

2. An example of a micellar system is a detergent solution, which contains surfactants that form micelles and help to break down dirt and oil particles.

Question:

What are the factors which influence the adsorption of a gas on a solid

Answer:

1. Temperature: Temperature affects the adsorption of a gas on a solid by influencing the kinetic energy of the gas molecules. At higher temperatures, the gas molecules move faster, making it more difficult for them to be adsorbed onto the solid surface.

2. Pressure: The pressure of the gas influences the adsorption of a gas on a solid. Higher pressures increase the number of gas molecules in contact with the solid surface, increasing the likelihood of adsorption.

3. Surface Area: The surface area of the solid affects the adsorption of a gas on a solid. Larger surface areas provide more places for gas molecules to be adsorbed onto.

4. Nature of the Solid: The nature of the solid affects the adsorption of a gas on a solid. Different solids have different chemical properties, which can affect the adsorption of a gas on the surface.

5. Nature of the Gas: The nature of the gas affects the adsorption of a gas on a solid. Different gases have different chemical properties, which can affect the adsorption of a gas on the surface.

6. Concentration: The concentration of the gas affects the adsorption of a gas on a solid. Higher concentrations of a gas increase the likelihood of adsorption.