15.3. Colloids and Suspensions http://www.ck12.org
rinsed off your hands or another surface because it is insoluble in water. However, the soap stabilizes a grease-water
mixture because one end of a soap molecule is polar, and the other end is nonpolar. This allows the grease to be
removed from your hands or your clothing by washing with soapy water.
Lesson Summary
- Suspensions and colloids are heterogeneous mixtures. A suspension is identifiable because its particles are
large and settle out of the dispersing medium due to the effects of gravity. - The dispersed particles of a colloid are intermediate in size between those of a solution and a suspension.
Colloids are distinguishable from solutions because of the light scattering phenomenon called the Tyndall
effect. Gels, aerosols, foams, and emulsions are some classes of colloids.
Lesson Review Questions
Reviewing Concepts
- How can you distinguish between a suspension and a solution?
- How big are the particles in a colloid compared to those of a suspension and a solution?
- What is the Tyndall effect? Why don’t solutions demonstrate the Tyndall effect?
- Explain the difference between the dispersed phase and the dispersing medium of a colloid.
- Explain the difference between an emulsion and an emulsifying agent.
- If you add a large spoonful of salt to a glass of standing water, the salt sinks to the bottom. Is this a suspension?
Explain.
Problems
- Identify each of the following descriptions or examples as being representative of a solution, suspension, or
colloid. More than one answer may apply.
a. dispersed particles can be filtered out
b. heterogeneous
c. particles are not visible to the unaided eye
d. paint
e. lemonade with no pulp
f. particle size larger than 1 nm
g. milk
h. particles do not settle upon standing
i. fog
Further Reading / Supplemental Links
- TypesofMixtures–Solutions,Suspensions,Colloids, (http://www.edinformatics.com/math_science/mixtures.htm