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Questions and Answers
What type of gels are rigid and do not have the property of elasticity?
What type of gels are rigid and do not have the property of elasticity?
What is the process of causing artificial rain by throwing the electrified sand or silver iodide from an aeroplane?
What is the process of causing artificial rain by throwing the electrified sand or silver iodide from an aeroplane?
What is the theory that proposes the formation of multimolecular layers of gas molecules on the surface of solids?
What is the theory that proposes the formation of multimolecular layers of gas molecules on the surface of solids?
What is the application of colloids in the purification of water?
What is the application of colloids in the purification of water?
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What type of catalysts are Bronsted acids and bases?
What type of catalysts are Bronsted acids and bases?
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What is the purpose of adding Al³⁺ ions to water in the purification process?
What is the purpose of adding Al³⁺ ions to water in the purification process?
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What is the study of the nature of surfaces and chemical and physical processes that take place on surfaces called?
What is the study of the nature of surfaces and chemical and physical processes that take place on surfaces called?
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What is the phenomenon of attracting and retaining molecules of a substance on the surface of a liquid or solid resulting in higher concentration of molecules on the surface called?
What is the phenomenon of attracting and retaining molecules of a substance on the surface of a liquid or solid resulting in higher concentration of molecules on the surface called?
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What is the term for the substance that gets adsorbed on any surface?
What is the term for the substance that gets adsorbed on any surface?
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What is the main cause of adsorption?
What is the main cause of adsorption?
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What is an example of adsorption?
What is an example of adsorption?
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What is the branch of physical chemistry that deals with the nature of surfaces and the chemical and physical processes that take place on surfaces?
What is the branch of physical chemistry that deals with the nature of surfaces and the chemical and physical processes that take place on surfaces?
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What is the primary function of soap and detergents in cleaning?
What is the primary function of soap and detergents in cleaning?
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What is the purpose of the froth floatation process?
What is the purpose of the froth floatation process?
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What is the property of certain precipitates, such as silver halide, that allows them to be used in adsorption indicators?
What is the property of certain precipitates, such as silver halide, that allows them to be used in adsorption indicators?
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What is the term for the catalytic process in which the reactants and the catalyst are in different phases?
What is the term for the catalytic process in which the reactants and the catalyst are in different phases?
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What is an example of heterogeneous catalysis?
What is an example of heterogeneous catalysis?
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What is the purpose of chromatographic analysis?
What is the purpose of chromatographic analysis?
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What is the limitation of the Freundlich adsorption isotherm?
What is the limitation of the Freundlich adsorption isotherm?
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What is the form of the solute in a solution that can undergo adsorption?
What is the form of the solute in a solution that can undergo adsorption?
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What is the name of the adsorption isotherm derived by Irving Langmuir in 1916?
What is the name of the adsorption isotherm derived by Irving Langmuir in 1916?
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What is the purpose of adding Al³⁺ ions to water in the purification process?
What is the purpose of adding Al³⁺ ions to water in the purification process?
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What is the process of causing artificial rain by throwing electrified sand or silver iodide from an aeroplane?
What is the process of causing artificial rain by throwing electrified sand or silver iodide from an aeroplane?
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What is the primary reason for the increased adsorption tendency of a substance when its surface area is increased?
What is the primary reason for the increased adsorption tendency of a substance when its surface area is increased?
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In which type of adsorption is the concentration of the adsorbed molecules always greater at the surface than in the bulk phase?
In which type of adsorption is the concentration of the adsorbed molecules always greater at the surface than in the bulk phase?
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What is the primary function of adding alum (Al³⁺ ions) to water in the purification process?
What is the primary function of adding alum (Al³⁺ ions) to water in the purification process?
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What is the purpose of throwing electrified sand or silver iodide from an aeroplane to induce artificial rain?
What is the purpose of throwing electrified sand or silver iodide from an aeroplane to induce artificial rain?
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What is the term for the graph that represents the amount of adsorbate adsorbed per unit mass of adsorbent at different pressures and temperatures?
What is the term for the graph that represents the amount of adsorbate adsorbed per unit mass of adsorbent at different pressures and temperatures?
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What is the primary mechanism behind the purification of water using adsorption?
What is the primary mechanism behind the purification of water using adsorption?
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What does the Freundlich adsorption isotherm equation indicate about the amount of gas adsorbed?
What does the Freundlich adsorption isotherm equation indicate about the amount of gas adsorbed?
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Under what conditions is Langmuir's theory of unimolecular adsorption valid?
Under what conditions is Langmuir's theory of unimolecular adsorption valid?
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What happens to the extent of adsorption at high pressure according to the Freundlich adsorption isotherm?
What happens to the extent of adsorption at high pressure according to the Freundlich adsorption isotherm?
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What is the relationship between the amount of gas adsorbed and pressure at low pressure according to the Freundlich adsorption isotherm?
What is the relationship between the amount of gas adsorbed and pressure at low pressure according to the Freundlich adsorption isotherm?
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What is the significance of the exponent n in the Freundlich adsorption isotherm equation?
What is the significance of the exponent n in the Freundlich adsorption isotherm equation?
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What is the physical significance of the slope of the plot of x/m against p in the Freundlich adsorption isotherm?
What is the physical significance of the slope of the plot of x/m against p in the Freundlich adsorption isotherm?
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Study Notes
Types of Gels
- Elastic gels: change shape when force is applied and return to original shape when force is removed (e.g. gelatin, agar-agar, starch)
- Non-elastic gels: rigid and do not have elasticity (e.g. silica gel)
Surface Chemistry
- Definition: branch of physical chemistry that deals with the nature of surfaces and chemical and physical processes that take place on surfaces
- Studies phenomenon of adsorption, catalysis, and colloidal properties
Adsorption
- Definition: phenomenon of attracting and retaining molecules of a substance on the surface of a liquid or solid, resulting in higher concentration of molecules on the surface
- Causes of adsorption: unbalanced forces of attraction or free valencies present at the solid or liquid surface
- Example: ammonia gas adsorbed on charcoal
Adsorption Isotherms
- Freundlich adsorption isotherm: describes adsorption where adsorbate forms a monomolecular layer on the surface of the adsorbent
- Equation: x/m = kp^(1/n)
- Characteristics: x/m increases with p at low pressure, becomes independent of p at high pressure, and depends on p^(1/n) at moderate pressure
- Langmuir adsorption isotherm: describes adsorption at low pressures and high temperatures, fails at high pressures and low temperatures
- Limitation: fails to describe multilayer adsorption
Classification of Adsorption
- Positive adsorption: concentration of adsorbate is more on the surface than in the bulk phase
- Example: adsorption of water vapors by anhydrous CaCl2
- Surface forces: unbalanced forces of attraction or free valencies present at the solid or liquid surface
- Examples: Vander Waal's forces, chemical bond forces
Applications of Colloids
- Purification of water: coagulation using alum
- Artificial rains: throwing electrified sand or silver iodide from an airplane to coagulate mist
- Cleaning agents: soap and detergents adsorb on the interface, reducing surface tension between dirt and cloth
- Froth floatation process: separating low-grade sulphide ore from silica and other earthy matter
- Adsorption indicators: surface of certain precipitates adsorbs dyes
- Chromatographic analysis: separating and analyzing mixtures
Catalysis
- Heterogeneous catalysis: catalytic process in which reactants and catalyst are in different phases
- Examples: surface chemistry, adsorption, and catalysis of chemical reactions
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Description
Test your knowledge of surface chemistry, including the concept of interfaces, phases, and adsorption. Learn about the branch of physical chemistry that deals with the nature of surfaces and the processes that occur on them.
