Colloids - Bridgman Public Schools

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Advanced Chemistry
Notes
Colloids
Colloids and Solutions
Recall: solutions were homogenous
mixtures
 Suspensions are a heterogeneous
mixture in which the particles
eventually settle out.
– Ex: muddy water
 Colloids
are intermediates of
solutions and suspensions.
Colloids
Colloids are defined as mixtures
composed of two or more phases of
matter.
 Dispersed
phase (colloid
particles) - larger than the single
particles of a solution but smaller
than the particles of a suspension.
 Continuous Phase – the dispersing
medium
Colloids
Colloids and Solutions
Comparison of Solutions, Suspensions and
Colloids
Type
Particle Size
Permanence
Solution
< 1 nm
> 1 nm but < 100
nm
Suspension
> 100 nm
Colloid
Permanent
Permanent
Settles out
Classification of Colloids
Colloids are based on the states of
the dispersed and continuous phases
 Aerosols – liquids and solids
dispersed in gases
– Ex: Smoke
 Foams
– gases dispersed in a liquid
or a solid
– Marshmallows; whipped cream
Classification of Colloids
Colloids are based on the states of
the dispersed and continuous phases
 Emulsions – liquids are dispersed in
other liquids or in solids
– Ex: Mayo, cheese,
 Sols
– dispersion of solids in liquids
or other solids
– Ex: paint, jelly, pearls
Properties of Colloids
Special properties of Colloids
 Tyndall effect – the scattering of
light by a colloid
Properties of Colloids
Special properties of Colloids
 Brownian Motion – continuous
random motion of colloid particles.
Properties of Solutions, Colloids and
Suspensions
Solution
Colloids
Suspensions
Don’t settle
Don’t settle
Settles
Doesn’t scatter
light
Unaffected by
membranes
Scatters light
Scatters light
Separated by
membrane
Separated by
membrane
Pass through filter Pass through filter Separated by filter
paper
paper
paper
unchanged
unchanged
Summary
Be able to…
 Define Colloid and Suspension
 Explain how Colloids relate to
Solutions and Suspensions in terms
of particle size and permanence
 Classify Colloids
 Describe properties of Colloids
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