1. COLLOIDS
Definition and Properties of Colloids
Classification of Colloids
Importance of ColloidsTo Daily Life

2. Classify Them!
 brine solution  ice cream soda
 muddy water  starch solution
 marshmallow  marbles in water
 butter  gelatin
 air  brass
 paint  ruby
 sand and water  pebbles and water
 soda

3. Solution Colloid Suspension
air butter marbles in
brass gelatin water
brine solution ice cream soda muddy water
soda marshmallow pebbles and
starch solution paint water
ruby sand and water

4. Comparison of the Properties of
Solutions, Colloids, And Suspensions
Property Solution Colloid Suspension
Particle Size Less than 1 nm 1 to 100 nm More than 100 nm
Appearance Clear Cloudy Cloudy
Homogeneity Homogeneous Homogeneous or Heterogeneous
Heterogeneous
Transparency Transparent but Often translucent Often opaque but
often colored and opaque but can be translucent
can be transparent
Separation Does not separate Does not separate Separates or settles
Filterability Passes through Passes through Particles do not
filter paper filter paper pass through filter
paper

5. Unique Properties of Colloids
 Tyndall Effect
 A beam of light
passing through
a transparent
pure colorless
solid, liquid or
gas cannot be
seen except at
the point where
it enters and
leaves the object.
 scattering of light

6.  Brownian Movement
 If a colloid is viewed
under a special
microscope, the
dispersed particles will
be seen moving in a
rapid, random, zigzag
motion through the
dispersion medium.
 This motion in a
colloid is one of the
reasons why particles
remain suspended
indefinitely.

7.  Electric Charge
 A dispersed colloidal particle can
adsorb electrically charged particles
on its surface.
 opposite attracts; same repel
 prevents coagulation and
OMG! precipitation of dispersed colloidal
You’re my particles
exact
opposite!
I think I am
attracted to
you!

8. activated carbon
 Adsoptive Property
 Adsoption is the process of collecting a thin layer of
molecules or ions of a substance with which it is in
contact.
 Surfaces of solids and liquids can adsorb molecules from
fluid phases (liquids and gases) onto their surface.
• Chemisorption – fairly strong, resembling chemical
bonds, and difficult to break
ex: activated charcoal
• Physisorption – weak, involves only Van der Waals
forces and the adsorbed material can usually
removed again.
ex: silica gel
silica gel

9. Animation References
 Animation of Tyndall Effect:
http://www.yteach.com/page.php/r
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 Animation of Brownian Movement:
www.edumedia-
sciences.com/en/a247-brownian-
motion

10. Classification of Colloids
 components : dispersed particles (solute)
and dispersing medium (solvent)
 can be classified according to:
 Phase
 Affinity Between Phases
Fabulous!

11. Types of Colloids
Dispersed Dispersion Name Examples
Particles Medium
Gas Liquid Foam Beaten egg white, shaving
cream, whipped cream, ice
cream soda
Gas Solid Solid foam Marshmallow, rubber foam
Liquid Gas Liquid aerosols Clouds, fog, mist, hair spray,
deodorant spray
Liquid Liquid Emulsion Milk, mayonnaise, blood
Liquid Solid Gel Cheese, butter, margarine

12. Dispersed Dispersion Name Examples
Particles Medium
Solid Gas Soild aerosol Smoke, dust in air
Solid Liquid Sol Paint, starch mixture, hot
chocolate, gelatin
Solid Solid Solid sol Colored glass, gem glass like
ruby and garnet

13. Classification According To
Phase
 AEROSOLS
 suspension of
liquid or solid
particles in
gas

14. solid foam
 FOAMS
 colloidal
liquid foam dispersions
of gas
bubbles in
liquids
(liquid
foams) or
solid (solid
foams)

15.  EMULSIONS
 colloidal dispersion of liquid
either a liquid or a solid.
 The 2 components of an
emulsion are usually
immiscible and require an
addition of emulsifying
agent or peptizing
agent to form stable
emulsion.
 If the dispersed particles in
an emulsion are relatively
large, they still tend to
separate from the dispersion
medium. This could be
prevented by the a process
called homogenization.

16.  SOLS
 a solid
dispersed in
either a
solid or a
liquid

17.  GELS
 a colloidal system in
which the dispersed
phase consists of
fibrous, interwoven
particles called
fibrils which exert a
marked effect on
the physical
properties of the
dispersing medium

18. Classification According to
Affinity Between Phases
 Lyophilic  solvent – loving; have a
strong attraction for the molecules of the
dispersing medium.
 Lyophobic  solvent –fearing; dispersed
phase are actually immiscible with the
solvent under normal conditions.