PHA 327 - Exam 2 - Disperse Systems 4

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PHA 327 - Exam 2 - Disperse Systems 4
2013-04-21 21:19:25
PHA 327 Exam Disperse Systems

PHA 327 - Exam 2 - Disperse Systems 4
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  1. The velocity of sedimentation has what units?
  2. What is the velocity of sedimentation proportional to?
    The Diameter ^2 and g (acc. Due to gravity)
  3. The diameter of the particle to the second power and the acceleration due to gravity are proportional to what other component of sedimentation?
    The velocity of sedimentation
  4. What process can be used for separation of colloidal particles?
  5. Define osmotic pressure:
    The pressure to be applied to a pure solvent to prevent it from passing into a solution by osmosis
  6. What is viscosity?
    The measure of resistance to liquid flow
  7. What is the unit of viscocity?
    Centipoise (cPs)
  8. What characteristic is measured in centipoise (cPs)?
  9. What are the three examples of liquids that exhibit Newtonian flow given in class?
    • Glycerin
    • Water
    • Ethyl Alcohol
  10. Glycerine, Ethyl Alcohol and Water all exhibit what type of flow?
  11. What is Newtonian flow?
    Rate of Shear is linearly related to Shearing stress
  12. What type of Non-Newtonian flow exist?
    • Plastic
    • Pseudoplastic
    • Dilatant
  13. What example was given in class of a liquid that displays plastic flow?
    Flocculated particles in suspensions
  14. Flocculated particles in suspensions exhibit what type of flow?
    Plastic (Non-Newtonian)
  15. Describe Plastic flow:
    • Viscosity decreases with increasing rate of shear
    • Elastic fluid until it meets the yield value then it exhibits Newtonian Flow
  16. What type of flow has decreasing viscosity with increasing rate of shear and behaves like an elastic fluid before reaching a yield value, after which it behave Newtonian?
    Plastic Flow
  17. What is stokes equation?
    • v =velocity of sedimentation (cm/sec)
    • d =diameter of the particle
    • n =viscosity of the medium
    • g =acceleration due to gravity
    • δp =density of the particle
    • δo =density of the medium
  18. The settling of particles can be described by what equation?
  19. Stoke equation describes what?
    The sedementation of particles
  20. What is the equation for Diffusion?

    • D = Diffusion coefficient
    • R = Gas constant
    • T = Absolute temp
    • η = Viscosity of the solvent
    • r = radius of the particle
    • N = Avogadro’s number
    • M = Molecular weight of the colloidal particle
    • ῡ= partial specific volume