Dispersed systems 1

    Cards (38)

    • What is a disperse system?
      A system with one phase in another phase
    • What are the components of a disperse system?
      • Disperse phase: the phase distributed
      • Continuous phase: the phase in which the disperse phase is distributed
    • What is the continuous phase in a suspension?
      Liquid
    • What is the disperse phase in a suspension?
      Solid
    • What is the continuous phase in a gel?
      Liquid
    • What is the disperse phase in a gel?
      Solid (higher concentration usually)
    • What is the continuous phase in an emulsion?
      Liquid
    • What is the disperse phase in an emulsion?
      Liquid
    • What is the continuous phase in a micellar system?
      Liquid
    • What is the disperse phase in a micellar system?
      Liquid (Molecular assemblies)
    • What is the continuous phase in an aerosol?
      Gas
    • What is the disperse phase in an aerosol?
      Solid
    • What is the continuous phase in a foam?
      Liquid
    • What is the disperse phase in a foam?
      Gas
    • What is the continuous phase in a solid dispersion?
      Solid
    • What is the disperse phase in a solid dispersion?
      Solid
    • What happens to the disperse phase over time in a pharmaceutical disperse system?
      • It may completely dissolve and form a solution
      • A small proportion may dissolve depending on solubility
      • Drug particles may be dispersed in a solution of the drug
    • What occurs when two immiscible liquids are mixed?
      Small amounts dissolve, but layers remain
    • What is partitioning in disperse systems?
      • Drug molecules can move between phases
      • Solvent molecules can also partition
      • Changes in composition can alter drug solubility
    • What is the classification of dispersions based on physical state?
      Suspension, emulsion, aerosol, foam
    • What are the two types of disperse systems based on size?
      • Coarse
      • Colloidal
      • Molecular (solution)
    • What is the size range for colloidal disperse phases?
      1 nm to 1 µm
    • What is the size range for coarse disperse phases?
      Greater than 1 µm
    • What are the characteristics of colloidal disperse systems?
      • Scatter light
      • Exhibit Brownian movement
      • Do not sediment easily
      • Can diffuse
    • What are the characteristics of coarse disperse systems?
      • Scatter light
      • Do not exhibit Brownian movement
      • Sediment easily
      • Cannot diffuse
    • What is the opposite of lyophilic?
      Lyophobic
    • What are the types of colloidal systems?
      • Lyophilic (solvent loving)
      • Lyophobic (solvent hating)
      • Amphiphilic (both segments in one molecule)
    • What are hydrophilic colloids?
      Colloids in water with similar attraction
    • What is a characteristic of lyophobic colloidal systems?
      They require energy to form
    • What do amphiphilic molecules do in an aqueous phase?
      • Orient to minimize hydrophobic exposure
      • Reduce surface tension
      • Form micelles at critical micelle concentration (CMC)
    • What is physical stability in disperse systems?
      • Ability to remain uniformly dispersed
      • Ensures consistent drug dosage
      • Affects patient administration
    • What is Brownian motion?
      Random movement of dispersed particles
    • What two forces affect particles in suspension?
      Gravity and drag force
    • What is Stokes' equation used for?
      To calculate sedimentation velocity
    • What does drag force depend on?
      Area, roughness, viscosity, velocity
    • What happens to a colloidal particle in suspension with increased temperature?
      It is displaced more by Brownian motion
    • How does drag force affect coarse suspensions?
      It can reduce sedimentation
    • What are the recommended background readings for this topic?
      • The physicochemical basis of pharmaceuticals by Moynihan and Crean
      • Aulton's Pharmaceutics (4th edition)