Colloids

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1. What is dialysis?

  • the electrophoretic mobility of the particles depends on the size , ccharge and shape.
  • diffusion of small molecules and ions from the colloid across the dialysation membrane eg cellophane which is permeable to small molecules and not colloid perticlaes
  • The removal of waste products from the blood (purpose of an artificial kidney)
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2. which of these is not a feature of a colloid?

  • settles by ultracentrifugation - cannot use filtration
  • > 500nm
  • Can be separated by electrophoresis because they often carry a charge
  • Can be seen by electric microscope
  • Contributes to the oncotic pressure
  • Allows dialysis
  • Because of their large size- they can induce light diffusion
  • Optical feature: Opalescent

3. which of these is not a way to classify Colloids?

  • Organic colloids - colloid particles (eg DNA, viruses, vesicles) or colloid systems(- blood plasma, lymph, cytosol)
  • Interaction with water - hydrophobic and hydrophillic
  • Structure of colloid - Molecular (sungle large molecule eg. proteins/starch) or micellar (particles composed from smaller amphillic ones eg. soap/phospholipids
  • Mobility of coloids eg solutions (free in their motion as in a true solution) and gel (particles arranged in a solid net e.g fibrin gel, gelatine

4. what is a protective colloid?

  • proteins in the blood are protective colloids of Calcium phosphate and calcium carbonate leading to its precipitation (forming gall stones)
  • A protective colloid are substances that form a hydrophobic colloid solution stabilizing the hydrophillic colloid particles.
  • A protective colloid are substances that form a hydrophilic colloid solution stabilizing the hydrophobic colloid particles.
  • A stubstance that specifically stabilises emulsions eg glycocholic (facilate absorption of dietary lipids)

5. Which of these will increase stabilization of a colloid particle?

  • Adding the ionic strength by adding
  • Adding water soluble organic solvent (destroys the lyosphere)
  • Add a little salt (eg. increases solubility of globulins)
  • Changing the Ph to its isoelectric point for amphoteric colloid particles like proteins

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