Interfacial Phenomena: Spreading of γ Water and Oleic Acid
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Questions and Answers

What is the interfacial tension between water and oleic acid as given in the text?

  • 12.8 dyne/cm
  • 10.5 dyne/cm
  • 20.3 dyne/cm
  • 15.6 dyne/cm (correct)

    • When will spreading occur according to the text?

  • Throughout the process
  • Only at the end
  • Initially (correct)
  • At random intervals

    • What happens after the initial spreading based on the text?

  • The liquid solidifies
  • A lens will form (correct)
  • The liquid evaporates
  • Spreading stops completely

    • In the given scenario, what would prevent a lens from forming?

    <p>Continuous spreading</p> Signup and view all the answers

    What is the significance of the interfacial tension value provided in the text?

    <p>Determines the behavior of water and oleic acid at their interface</p> Signup and view all the answers

    What is necessary to resuspend and redisperse particles?

    <p>Overcome forces</p> Signup and view all the answers

    Which action facilitates the process of resuspending and redispersing particles?

    <p>Applying more force</p> Signup and view all the answers

    What is the main challenge in resuspending and redispersing particles?

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

    What role do forces play in the process of resuspending and redispersing particles?

    <p>They need to be overcome</p> Signup and view all the answers

    Why is overcoming forces crucial in the resuspension and redispersion of particles?

    <p>To break particle aggregates</p> Signup and view all the answers

    Why do the majority of particles dispersed in water acquire a negative charge?

    <p>Due to preferential adsorption of the hydroxyl ion</p> Signup and view all the answers

    Which ion is more hydrated, leading to its preference to be in the bulk of the aqueous medium?

    <p>Hydronium ion</p> Signup and view all the answers

    What is the primary reason for hydroxyl ions to be adsorbed at the surface of particles?

    <p>They are less hydrated than hydronium ions</p> Signup and view all the answers

    What leads to the charges on particles according to the text?

    <p>Ionization of groups at the particle surface</p> Signup and view all the answers

    Which ion has a greater tendency to be in the bulk of the aqueous medium based on its hydration level?

    <p>Hydronium ion</p> Signup and view all the answers

    What happens when the zeta potential is reduced below a certain value?

    <p>Attractions forces exceed repulsive forces</p> Signup and view all the answers

    How do particles behave when the zeta potential is lowered beyond a specific threshold?

    <p>They come closer together</p> Signup and view all the answers

    What is the consequence of attractive forces exceeding repulsive forces in a system?

    <p>Particles aggregate</p> Signup and view all the answers

    Which statement is true when the zeta potential falls below a system-dependent threshold?

    <p>Particles start coming together</p> Signup and view all the answers

    What occurs if the attractive forces between particles are stronger than the repulsive forces in a system?

    <p>Particles aggregate</p> Signup and view all the answers

    What is the purpose of the curves shown in the liquid phase?

    <p>To represent ions or molecules</p> Signup and view all the answers

    Which characteristic is NOT depicted by the curves in the liquid phase?

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

    What does the term 'liquid phase' refer to in this context?

    <p>A state of matter with particles that flow</p> Signup and view all the answers

    What does the presence of curves suggest about the ions or molecules in the liquid phase?

    <p>They are interacting with each other</p> Signup and view all the answers

    Which property of ions or molecules is likely NOT indicated by the curves in the liquid phase?

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

    What term is customarily used when referring to either a gas-solid or a gas-liquid interface?

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

    In pharmacy, which of the following is an example of practical significance related to solid-solid interfaces?

    <p>Flow of particles</p> Signup and view all the answers

    What is a key application of solid-solid interfaces in pharmacy according to the text?

    <p>Preparation of layered tablets</p> Signup and view all the answers

    Which of the following is NOT mentioned as a practical significance of solid-solid interfaces in pharmacy in the text?

    <p>Zeta potential threshold</p> Signup and view all the answers

    When referring to interfaces, what does the term 'surface' encompass according to the text?

    <p>Gas-liquid interfaces</p> Signup and view all the answers

    What happens to the excess anions in the equilibrium situation described in the text?

    <p>Approach the surface</p> Signup and view all the answers

    How are the remainders of excess anions distributed as one moves away from the charged surface?

    <p>In decreasing amounts</p> Signup and view all the answers

    What term best describes the distribution of excess anions in the equilibrium scenario mentioned?

    <p>Radial dispersion</p> Signup and view all the answers

    What characterizes the equilibrium situation established with respect to excess anions near the charged surface?

    <p>Radial migration</p> Signup and view all the answers

    In the described equilibrium, why do some of the excess anions approach the surface?

    <p>As a result of attractive forces</p> Signup and view all the answers

    What is the final spreading coefficient after equilibration?

    <p>33.4 dynes/cm</p> Signup and view all the answers

    What does a greater spreading coefficient value indicate in this context?

    <p>Increased adhesion between the liquid and solid</p> Signup and view all the answers

    How would the system behave if the final spreading coefficient was negative?

    <p>Spreading would cease and the liquid would retract from the solid surface</p> Signup and view all the answers

    In this scenario, what would a decrease in the solid surface tension lead to?

    <p>Increase in spreading coefficient</p> Signup and view all the answers

    What effect would an increase in both γS′ and γL′ have on the spreading coefficient?

    <p>No effect on spreading coefficient</p> Signup and view all the answers

    What is the mechanism of cell death mentioned in the text?

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

    Which type of organisms are susceptible to the action of cationic quaternary compounds according to the text?

    <p>Both gram-positive and gram-negative organisms</p> Signup and view all the answers

    What property of interfaces is discussed in Chapter 15 of Interfacial Phenomena?

    <p>Electric properties</p> Signup and view all the answers

    What is the role of charge on the surface of a particle in interfacial phenomena?

    <p>Facilitate resuspension</p> Signup and view all the answers

    What results in the death of cells according to the text?

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

    Which type of particles are described as settling rapidly, not forming a cake, and easily resuspended?

    <p>Flocculated particles</p> Signup and view all the answers

    What is a characteristic of flocculated particles when the zeta potential is decreased beyond a specific threshold?

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

    Why do flocculated particles settle rapidly?

    <p>Weak bonding forces</p> Signup and view all the answers

    What happens to flocculated particles in terms of cake formation compared to agglomerated particles?

    <p>Agglomerated particles form a cake, flocculated particles do not</p> Signup and view all the answers

    What distinguishes flocculated particles from colloidal particles?

    <p>Formation of a cake</p> Signup and view all the answers

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