Interfacial Tension: Adhesive and Cohesive Forces
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What is the condition for adhesive forces between two liquids to be more than cohesive forces?

  • The cohesive forces within each liquid are negligible
  • The liquids are partially miscible
  • The liquids are completely immiscible
  • The interfacial tension between them is zero (correct)

    • What happens when two liquids are completely miscible?

  • They form a distinct boundary
  • They are immiscible
  • There is no interfacial tension between them (correct)
  • They repel each other

    • What is the relationship between adhesive forces and cohesive forces when they are in equilibrium?

  • Adhesive forces do not depend on cohesive forces
  • Adhesive forces are more than cohesive forces
  • Adhesive forces are less than cohesive forces
  • Adhesive forces are equal to cohesive forces (correct)

    • Which of the following is a characteristic of two immiscible liquids?

    <p>They have high interfacial tension</p> Signup and view all the answers

    What happens when the adhesive forces between two liquids are less than the cohesive forces?

    <p>The liquids are immiscible</p> Signup and view all the answers

    What happens if a substance is too lipophilic?

    <p>It dissolves completely in the oil phase and little appears at the interface</p> Signup and view all the answers

    What is the relationship between a substance's lipophilicity and its adsorption?

    <p>High lipophilicity results in negative adsorption in the bulk</p> Signup and view all the answers

    What is negative adsorption related to?

    <p>Materials that are found in the bulk of liquid</p> Signup and view all the answers

    What happens if a substance has a balance of lipophilicity and hydrophilicity?

    <p>The information is not sufficient to determine what happens</p> Signup and view all the answers

    What is the opposite of negative adsorption?

    <p>Positive adsorption</p> Signup and view all the answers

    What happens when a liquid spreads over a surface?

    <p>It covers all or a part of the surface</p> Signup and view all the answers

    What is the extent of surface coverage when a liquid spreads?

    <p>It covers all or a part of the surface</p> Signup and view all the answers

    What is the primary outcome when a liquid spreads over a substrate?

    <p>The liquid covers all or a part of the surface</p> Signup and view all the answers

    What is a possible consequence of a liquid spreading over a surface?

    <p>The surface is partially or fully covered</p> Signup and view all the answers

    What can be said about the surface after a liquid spreads over it?

    <p>It becomes partially or fully covered</p> Signup and view all the answers

    Where does electric neutrality occur when the counterions in the tightly bound, solvated layer equal the positive charge on the solid surface?

    <p>Plane bb′</p> Signup and view all the answers

    What is the condition for electric neutrality to occur at plane bb′?

    <p>The counterions equal the positive charge on the solid surface</p> Signup and view all the answers

    What happens when the counterions in the tightly bound, solvated layer do not equal the positive charge on the solid surface?

    <p>Electric neutrality does not occur at either plane</p> Signup and view all the answers

    What is the role of the tightly bound, solvated layer in achieving electric neutrality?

    <p>It neutralizes the positive charge on the solid surface</p> Signup and view all the answers

    What is the significance of plane cc′ in the context of electric neutrality?

    <p>It is where electric neutrality occurs when the counterions do not equal the positive charge</p> Signup and view all the answers

    Why is it necessary to overcome certain forces when resuspending and redispersing particles?

    <p>To break the adhesive and cohesive forces between particles</p> Signup and view all the answers

    What type of forces are responsible for holding particles together?

    <p>Adhesive and cohesive forces</p> Signup and view all the answers

    What is the result of not overcoming the forces holding particles together?

    <p>The particles will remain aggregated</p> Signup and view all the answers

    What is the purpose of overcoming the forces holding particles together?

    <p>To resuspend and redisperse the particles</p> Signup and view all the answers

    What is required to redisperse particles?

    <p>Overcoming the adhesive and cohesive forces</p> Signup and view all the answers

    What is the primary reason why water can wet the glass?

    <p>Cohesive forces between water molecules are weaker than adhesive forces between water and glass</p> Signup and view all the answers

    What is the shape of the surface of the capillary tube that allows water to rise?

    <p>Concave</p> Signup and view all the answers

    What is the primary direction of the force experienced by molecules at the surface of a liquid?

    <p>Inward, toward the bulk</p> Signup and view all the answers

    What is the result of adhesive forces being greater than cohesive forces between water molecules?

    <p>Water spreads over the surface</p> Signup and view all the answers

    What is the reason for the inward force experienced by molecules at the surface of a liquid?

    <p>The molecules at the surface are subject to cohesive forces from the bulk</p> Signup and view all the answers

    What is the relationship between adhesive forces and the shape of the capillary tube?

    <p>Adhesive forces increase with a concave surface</p> Signup and view all the answers

    What is the significance of the concave surface in the context of water rising in the capillary tube?

    <p>It increases the adhesive forces between water and glass</p> Signup and view all the answers

    What is the net result of the force experienced by molecules at the surface of a liquid?

    <p>A minimization of the surface area of the liquid</p> Signup and view all the answers

    What is the relationship between the force experienced by molecules at the surface of a liquid and the surface tension?

    <p>The force experienced by molecules at the surface is a result of the surface tension</p> Signup and view all the answers

    What is the significance of the force experienced by molecules at the surface of a liquid in interfacial phenomena?

    <p>It plays a crucial role in shaping the interface between two liquids or a liquid and a solid</p> Signup and view all the answers

    What is the primary reason for the formation of micelles in the bulk?

    <p>The concentration of surface active molecules exceeds the critical micelle concentration</p> Signup and view all the answers

    What happens to the surface of the water as more surface active agent is added?

    <p>The surface of the water becomes saturated with surface active molecules</p> Signup and view all the answers

    What is the state of the surface of the water when micelles start forming?

    <p>The surface is saturated with surface active molecules</p> Signup and view all the answers

    What is the consequence of adding more surface active agent to the water beyond the point of saturation?

    <p>Micelles start forming in the bulk</p> Signup and view all the answers

    What is the critical point at which micelles start forming in the bulk?

    <p>When the surface is saturated with surface active molecules</p> Signup and view all the answers

    What is the effect of a low concentration of surfactant on the activity of an anthelmintic drug?

    <p>It potentiates the activity of the drug.</p> Signup and view all the answers

    What is the significance of surfactants in the context of drug activity?

    <p>They can either enhance or inhibit the activity of anthelmintic drugs, depending on the concentration.</p> Signup and view all the answers

    What is the relationship between surfactant concentration and anthelmintic drug activity?

    <p>A low concentration of surfactant can potentiate the activity of anthelmintic drugs.</p> Signup and view all the answers

    What is the primary effect of a low concentration of surfactant on the activity of anthelmintic drugs?

    <p>It increases the potency of the drug.</p> Signup and view all the answers

    What is the implication of a low concentration of surfactant on the efficacy of anthelmintic treatment?

    <p>It increases the efficacy of the treatment.</p> Signup and view all the answers

    What is typically found in the region adjacent to the surface layer?

    <p>Tightly bound solvent molecules and negative ions</p> Signup and view all the answers

    What is the primary composition of the layer tightly bound to the surface?

    <p>Solvent molecules and negative ions</p> Signup and view all the answers

    What type of ions are typically found in the region adjacent to the surface layer?

    <p>Only negative ions</p> Signup and view all the answers

    What is the characteristic of the solvent molecules in the region adjacent to the surface layer?

    <p>They are tightly bound to the surface</p> Signup and view all the answers

    What is the relationship between the solvent molecules and ions in the region adjacent to the surface layer?

    <p>The solvent molecules attract the ions</p> Signup and view all the answers

    What happens if a molecule is too hydrophilic?

    <p>It remains within the body of the aqueous phase and exerts no effect at the interface</p> Signup and view all the answers

    What is the effect of a molecule's hydrophilicity on its behavior at the interface?

    <p>It decreases its adsorption</p> Signup and view all the answers

    What determines whether a molecule exerts an effect at the interface?

    <p>Its hydrophilicity</p> Signup and view all the answers

    What happens when a molecule is not adsorbed at the interface?

    <p>It remains within the body of the aqueous phase</p> Signup and view all the answers

    What is the result of a molecule being too hydrophilic?

    <p>It remains within the body of the aqueous phase</p> Signup and view all the answers

    What is the primary mode of death for cells exposed to cationic quaternary compounds?

    <p>Loss of essential materials</p> Signup and view all the answers

    What is the primary function of cationic quaternary compounds?

    <p>To disrupt cell membranes</p> Signup and view all the answers

    What is the likely outcome when a gram-positive organism is exposed to a cationic quaternary compound?

    <p>Cell membrane disruption</p> Signup and view all the answers

    What is the characteristic of the surface of a particle in relation to electric properties?

    <p>It has a positive charge</p> Signup and view all the answers

    What is the relationship between electric properties and interfacial phenomena?

    <p>They are directly related</p> Signup and view all the answers

    What happens to the surface of the substance when some of the cations are adsorbed onto it?

    <p>It becomes positively charged</p> Signup and view all the answers

    What is the result of the adsorption of cations onto the surface of the substance?

    <p>The surface becomes positively charged</p> Signup and view all the answers

    Why do some of the cations adsorb onto the surface of the substance?

    <p>To give the surface a positive charge</p> Signup and view all the answers

    What is the effect of the adsorption of cations on the surface properties of the substance?

    <p>It gives the surface a positive charge</p> Signup and view all the answers

    What is the consequence of the adsorption of cations onto the surface of the substance?

    <p>The surface becomes positively charged</p> Signup and view all the answers

    What is the potential at the solid surface due to the potential-determining ion defined as?

    <p>The difference in potential between the actual surface and the electroneutral region of the solution</p> Signup and view all the answers

    What is the significance of the electrothermodynamic potential?

    <p>It is the potential difference between the actual surface and the electroneutral region of the solution</p> Signup and view all the answers

    What is the role of the electroneutral region of the solution?

    <p>It is the region where the electroneutralization of the solid surface occurs</p> Signup and view all the answers

    What is the relationship between the electrothermodynamic potential and the solid surface?

    <p>The electrothermodynamic potential is dependent on the solid surface</p> Signup and view all the answers

    What is the condition for the electrothermodynamic potential to be significant?

    <p>When the electroneutral region of the solution is adjacent to the solid surface</p> Signup and view all the answers

    What is a characteristic of flocculated particles?

    <p>They settle rapidly</p> Signup and view all the answers

    What happens when flocculated particles settle?

    <p>They settle rapidly</p> Signup and view all the answers

    What is a characteristic of the bond between flocculated particles?

    <p>It is weak and flexible</p> Signup and view all the answers

    What can be done to flocculated particles once they have settled?

    <p>They can be resuspended</p> Signup and view all the answers

    What is NOT a characteristic of flocculated particles?

    <p>They form a hard cake</p> Signup and view all the answers

    Study Notes

    Adhesive and Cohesive Forces

    • Adhesive forces between two liquids are greater than cohesive forces within the liquids
    • If two liquids are completely miscible, no interfacial tension exists between them

    Interfacial Phenomena

    • When a liquid spreads over a surface, it covers all or part of the surface
    • Adhesive forces between a liquid and a surface can cause the liquid to rise in a capillary tube with a concave surface (e.g., water and glass)

    Surfactants and Interfacial Tension

    • Surfactants can affect the activity of a drug, with a low concentration of surfactant potentiating the activity of an anthelmintic drug
    • As more surface-active agents are added to water, the surface of the water is covered by molecules of the surface-active agent, leading to micelle formation

    Micelle Formation

    • Micelles are formed when surface-active agents are added to water, causing them to aggregate and form spherical structures
    • Micelle formation occurs when the surface of the water is saturated with surface-active molecules, and any increase in their concentration causes them to form micelles in the bulk

    Electrical Properties of Interfaces

    • Electric properties of interfaces refer to the charge on the surface of a particle
    • The potential at the solid surface is defined as the electrothermodynamic (Nernst) potential, which is the difference in potential between the actual surface and the electroneutral region of the solution
    • Flocculated particles are weakly bonded, settle rapidly, do not form a cake, and are easily resuspended

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    Description

    This quiz covers the relationship between adhesive and cohesive forces in liquids, and how it affects interfacial tension. Learn about the conditions under which interfacial tension exists or disappears.

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