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Chemistry
Elements and Compounds

What is a colloid?

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February 25, 2012 7:02AM

A type of solution of intermediate sized particles suspended and completely dispersed in another substance. Because the particles are not completely dissolved (although dispersed), it may or may not be a homogeneous mixture. Depending on the size of particles, the solution can be either; particles that are less than 10-9 m are homogeneous mixtures, particles that are 10-9- 10-6 m are colloids, and particles that are greater than 10-6 m are heterogeneous mixtures.

Colloids also exhibit the Tyndall effect, in which a beam of light is visible from the side, yet still passes through the solution. (You can see lasers through a mist or fog.)

Classifications:

  • Aerosol (liquid disbursed in a gas - fog)
  • Foam (gas disbursed in a liquid - shaving cream)
  • Solid Foam (gas disbursed in a solid - Styrofoam)
  • Emulsion (liquid disbursed in a liquid - butter)
  • Gel (liquid disbursed in a solid - jello)
  • Solid Aerosol (solid disbursed in a gas - smoke)
  • Sol (solid disbursed in a liquid - blood)
  • Solid Sol (solid disbursed in a solid - alloy)

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