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DF33 Good and Bad Emulsions

Mer Scott 9 questions

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Questions in this quiz (9)

  1. 1The theory for miscibility tests is that if you add water to an [blank_start]o/w emulsion[blank_end], nothing will happen, or if you add oil into a [blank_start]w/o emulsion[blank_end], nothing will happen. However for example if you add more [blank_start]oil[blank_end] to a o/w emulsion it may begin to cream and coalesce.
    1. Ao/w emulsion
    2. Bw/o emulsion
    3. Coil
    4. Dwater
  2. 2In a viscosity test the critical point is defined as the [blank_start]concentration[blank_end] of the internal/dispersed phase [blank_start]above which[blank_end] the emulsifying agent cannot produce a [blank_start]stable[blank_end] emulsion of the desired type. For spherical globules this is [blank_start]74%[blank_end].
    For example, as you add more oil to a o/w emulsion the oil fraction will [blank_start]increase[blank_end] and so [blank_start]viscosity[blank_end] will increase, up to the critical point. At this point [blank_start]inversion[blank_end] occurs and the emulsion will become a [blank_start]w/o emulsion[blank_end].
    1. Aconcentration
    2. Babove which
    3. Cstable
    4. D74%
    5. E64%
    6. F72%
    7. Gincrease
    8. Hviscosity
    9. Iinversion
    10. Jw/o emulsion
  3. 3Methylene blue is an oil-soluble dye and Sudan III is a water-soluble dye.
    1. ATrue
    2. BFalse
  4. 4Choose the incorrect statement.
    1. AFlocculation precedes coalescence.
    2. BFlocculation decreases likelihood of creaming.
    3. CCreaming increases the likelihood of coalescence.
    4. DCreaming is reversible by shaking.
  5. 5Causes of cracking:
    – Addition of a substance that is [blank_start]incompatible[blank_end] with the emulsifying agent which r[blank_start]educes its emulsifying ability[blank_end]
    – Change in [blank_start]temperature[blank_end]
    – Incorporation of [blank_start]excessive amounts[blank_end] of the dispersed phase
    1. Aincompatible
    2. Beduces its emulsifying ability
    3. Ctemperature
    4. Dexcessive amounts
  6. 6Phase inversion can occur if [blank_start]HLB[blank_end] of the surfactant is altered. Addition of an [blank_start]electrolyte[blank_end] which alters the HLB or change in [blank_start]temperature[blank_end] can alter the HLB. E.g. an o/w emulsion which has [blank_start]sodium stearate[blank_end] as the emulsifying agent can be inverted by addition of CaCl2, because it forms [blank_start]calcium stearate[blank_end], a lipophilic emulsifying agent that favours formation of a [blank_start]w/o emulsion[blank_end].
    1. AHLB
    2. Belectrolyte
    3. Ctemperature
    4. Dsodium stearate
    5. Ecalcium stearate
    6. Fw/o emulsion
  7. 7Methods of Evaluation and Assessment of Emulsion Stability:
    1. [blank_start]Macroscopic[blank_end] examination
    2. Ageing
    – [blank_start]Size[blank_end] distribution and [blank_start]phase[blank_end] separation analysis from [blank_start]time to time[blank_end] as the product ages
    3. Temperature & Centrifugation
    – Acceleration of the [blank_start]rate[blank_end] of creaming or coalescence
    – Freezing, [blank_start]thaw-freeze cycles[blank_end]

    Note: Accelerated stability tests are known as STRESS TESTS
    1. AMacroscopic
    2. BSize
    3. Cphase
    4. Dtime to time
    5. Erate
    6. Fthaw-freeze cycles
  8. 8Physical parameters measured during stress testing:
    1. Phase separation
    • Measure volume of the separated phase
    • [blank_start]Compare[blank_end] composition of sample from the [blank_start]top and bottom[blank_end] of the emulsion → Is [blank_start]conductivity[blank_end] the same or different?
    2. Droplet size and size distribution
    • Use microscope or Coulter counter or laser diffraction sizing
    • Increased [blank_start]size[blank_end] = decrease number count = likelier [blank_start]Coalescence[blank_end]
    3. Viscosity
    • Decreased droplet size = [blank_start]increased viscosity[blank_end]
    • Increased size distribution = [blank_start]decreased viscosity[blank_end]
    1. ACompare
    2. Btop and bottom
    3. Cconductivity
    4. Dsize
    5. Ecoalescence
    6. Fincreased viscosity
    7. Gdecreased viscosity
  9. 9The formulator can decrease likelihood of creaming by controlling the state of [blank_start]flocculation[blank_end], the droplet [blank_start]size and size distribution[blank_end] of the dispersed phase, and the [blank_start]viscosity[blank_end] of the continuous phase. Likelihood of flocculation can be decreased by having [blank_start]high charge density[blank_end] on droplet surfaces. The formulation can choose an [blank_start]emulsifying agent[blank_end] that prevents coalescence by forming a [blank_start]condensed film[blank_end] around dispersed droplets.
    1. Aflocculation
    2. Bsize and size distribution
    3. Cviscosity
    4. Dhigh charge density
    5. Econdensed film
    6. Femulsifying agent

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Description
PHCY211 (Formulation) Quiz on DF33 Good and Bad Emulsions, created by Mer Scott on 06/05/2018.
Author
Mer Scott
Language
English
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