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DF25 Boundaries

Mer Scott 7 questions

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Questions in this quiz (7)

  1. 1Which of these is not an interfacial phenomena?
    1. ASurafce and interfacial tension
    2. BAdsorption
    3. CWetting/Contact angle and Spreading
    4. DAbsorption
  2. 2Forces at play:
    1. Cohesive forces
    • Forces between [blank_start]like[blank_end] molecules
    • Intermolecular forces e.g. [blank_start]H-bonds, van Der Waals forces[blank_end]
    - In the bulk – net cohesive force = [blank_start]ZERO[blank_end], molecules being pulled [blank_start]equally[blank_end] in all directions. Surface molecules are [blank_start]unequally attracted[blank_end] to other molecules .
    2. Adhesive forces
    • Forces between [blank_start]unlike[blank_end] molecules
    • [blank_start]Mechanical, electrostatic[blank_end] forces
    1. Alike
    2. Bunlike
    3. CH-bonds, van Der Waals forces
    4. DMechanical, electrostatic
    5. EZERO
    6. Fequally
    7. Gunequally attracted
  3. 3- Surface tension (γ): to [blank_start]minimise[blank_end] surface area. At the surface there is inwards [blank_start]force[blank_end] directed towards the [blank_start]bulk[blank_end].
    - Interfacial tension (γLL) : The force per unit length existing at the [blank_start]interface[blank_end] between 2 [blank_start]immiscible[blank_end] liquid phases
    1. Aminimise
    2. Bmaximise
    3. Cforce
    4. Dvibration
    5. Ebulk
    6. Finterface
    7. Ginterface
    8. Hsurface
    9. Iimmiscible
    10. Jmiscible
  4. 4- Contact angle: the angle formed between a liquid droplet and the surface
    over which it spreads. [blank_start]Low values of < 90 degrees[blank_end] indicate that the liquid spreads or wets the solid surface well.
    - Wettability: [blank_start]quantitative[blank_end] measure of the wetting of a [blank_start]solid[blank_end] by a [blank_start]liquid[blank_end].
    - Wetting agent: A compound that [blank_start]lowers[blank_end] the contact angle between the particle surface and the liquid, eg Surfactants, Alcohol, Glycerin
    1. ALow values of < 90 degrees
    2. BHigh values of > 90 degrees
    3. Cquantitative
    4. Dsolid
    5. Eliquid
    6. Flowers
    7. Graises
  5. 5Types of adsorption:
    1. Physical
    Adsorbate is bound via [blank_start]weak secondary[blank_end] forces. Removal of adsorbate
    from the adsorbent – process known as
    [blank_start]desorption[blank_end] (increase [blank_start]temperature[blank_end] and decrease [blank_start]pressure[blank_end])
    2. Chemical (Chemisorption)
    Adsorbate is bound via [blank_start]primary[blank_end] forces. Specific binding, may require an [blank_start]activation energy[blank_end]∴ slow and [blank_start]not readily reversible[blank_end]. Only a [blank_start]monolayer[blank_end] is
    possible.
    1. Aweak secondary
    2. Bprimary
    3. Cdesorption
    4. Dtemperature
    5. Epressure
    6. Factivation energy
    7. Gnot readily reversible
    8. Hmonolayer
  6. 6Unwanted effects of adsorption:
    • Adsorption of drugs by [blank_start]adsorbents[blank_end] taken [blank_start]simultaneously[blank_end] by a patient e.g. adsorption of drugs (NSAIDs, Glipizide) onto [blank_start]coadministered antacids[blank_end] Mg(OH)2 or Al(OH)3
    • Adsorption of drugs onto the [blank_start]walls of a container[blank_end] e.g. loss of insulin in an intravenous line
    • Adsorption of drugs onto [blank_start]excipients[blank_end] e.g. phenytoin adsorption by dicalcium phosphate tablet filler
    1. Asimultaneously
    2. Bcoadministered antacids
    3. Cwalls of a container
    4. Dadsorbents
    5. Eexcipients
  7. 7Choose the incorrect statement about surfactants
    1. AAccumulate at an interface and result in decreased surface
      tension
    2. BLarge molecules with a lipophilic group ‘tail’ and a hydrophilic group ‘head group’
    3. CMany drugs are surface active (amphipathic nature)
    4. DWetting, emulsifying, and solubilising agents
    5. EHeadgroup can be cationic, anionic, or zwitterionic
    6. FSorbitan esters are nonionic surfactants generally
      immiscible in water and are W/O emulsifiers
    7. GPolysorbates are nonionic surfactants miscible in
      water are are O/W) emulsifiers
    8. HTween 80 is a sorbitan ester
    9. IO/W emulsifying agents have HLBs from 3-8, while W/O emulsifying agents have HLBs 8 - 16

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Description
PHCY211 (Formulation) Quiz on DF25 Boundaries, created by Mer Scott on 05/05/2018.
Author
Mer Scott
Language
English
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