What are Suspensions and Colloids?

Contributed by:
Jonathan James
The highlights are:
1. Homogeneous and heterogeneous matter
2. Solutions
3. Suspension
4. Colloids
5. Tyndall Effect
1.
2. Matter
Pure substance:
• Fixed (constant) composition and unique properties.
• Contains only 1 type of particle
• Can be an element (like Cu) or a compound (like NaCl)
• Homogeneous (looks the same throughout)
• Contains at least 2 PHYSICALLY combined substances
• can be homogeneous or heterogeneous.
3. Homogeneous Matter
• Looks the same throughout
• Particles are evenly distributed
• Properties are uniform
• Can be pure or a mixture
– Element: pure substance, only 1 type of atom
– Compound: pure substance, 2 or more CHEMICALLY
combined elements
• (not easily separated from each other)
• Ex: water, CO2 , NaCl
– Solution: a special kind of mixture
• SOLUTE dissolves & SOLVENT does the dissolving
• PHYSICALLY combined and can be PHYSICALLY separated
Ex: food coloring and water
salt water
4. Heterogeneous Matter
• Does not look the same throughout
• Particles are not evenly distributed
• Properties are not uniform
• Always a MIXTURE (solutions are
mixtures that are NOT heterogeneous)
• 2 or more PHYSICALLY combined
substances
5. MATTER
No Is it uniform Yes
throughout?
Heterogeneous Homogeneous
No Can it be separated yes
by physical means?
Pure Substance Solution
No Can it be decomposed yes
into other substance by
a chemical process?
Element Compound
6. Homogeneus Mixtures (Solutions)
• Homogeneous mixture:
– a mixture in which the components are
evenly distributed among each other.
– You cannot see the component parts.
• Homogeneous means the same
throughout.
• It has a constant composition
throughout.
Examples: Salt dissolved in water,
sugar dissolved in water, apple
juice, tea, copper (II) sulfate
solution in water, alloys....
7. Solutions
• Well-mixed (uniform) –
single phase
• homogeneous
• transparent (if liquid)
• cannot be separated by
filter
• do not separate on standing
8. States of Matter in Solution Examples of Solutions
gas in gas air ( N2, O2 , Ar, CO2 , other
gases)
gas in liquid soda pop (CO2 in water)
liquid in liquid gasoline (a mixture of
hydrocarbon compounds)
solid in liquid Salt water
gas in solid H2 in platinum or palladium
liquid in solid dental amalgams (mercury
in silver)
solid in solid alloys ( brass, (Cu/Zn), sol-
der (Sn/Pb), Steel (Fe/C ))
9. Q: Can a solution be separated by
filtration?
A. Yes
B. No
10. Heterogeneous Mixtures
Heterogeneous Mixture (Suspension or Colloid):
•the components are not evenly distributed among each
•has two or more distinct phases that are usually visible
•does NOT have uniform properties.
•Heterogeneous mixtures that look like solutions can be
distinguished because they scatter light (Tyndall Effect).
Ex: muddy water, oil
and water, milk, sulfur
and iron, granite,
11. Q: After passing through a muddy pond, the
water in a stream contains dirt particles.
Which of the following describes the stream?
A. solution
B. suspension
C. pure substance
D. colloid
12. Suspensions
• A suspension is a mixture where the particles
are dispersed but are big enough to settle out
or be filtered out.
• A mixture that needs to be shaken before use
is probably a suspension.
• Ex.
– Mud or muddy water, where soil, clay, or silt
particles are suspended in water.
– Paint (needs to be mixed before use)
– Snow globe (eventually settles)
– Orange Juice (needs to be shaken before use)
13. •Suspensions like coffee are easily
filtered to take out the tiny solid
clumps floating in the liquid.
• Solutions are mixtures that have particles that
are so small they pass through most filters.
14. Colloids
Colloids
Non-transparent, uniform, large particles, cloudy (milky)
but stable system
15. Colloids
Tyndall Effect
• You can see the light
beam as it passes
through a colloid or
suspension.
• particles scatter light
16. Q: Which of the following will show
the Tyndall Effect?
A. water
B. sugar water
C. oxygen gas
D. fog
17. Q: Which of the following is a
colloid?
A. milk
B. NaCl in water
C. sand and water
D. raisin bread
18. 3 Types of MIXTURES
Solution Colloid Suspension
Examples salt water, Jello, fog, milk Muddy water,
air, brass Italian dressing
Particle Type ions, atoms, Small Clusters Large Clusters
molecules
Particle Size small medium large
Scatter Light? No yes yes
(TYNDALL EFFECT)
Settle while standing? No No yes
Separate by filtration? No No yes
19.
20. • Matter can also be classified according to
its composition.
• Mixtures can be homogeneous or
heterogeneous.
• Mixtures can be separated into pure
substances, and pure substances can be
either compounds or elements.
21. • Homogeneous Matter
– Looks the _____________ throughout
– Particles are _____________ distributed
– Properties are _____________
• Heterogeneous Matter
– ________________ look the same throughout
– Particles are __________________ distributed
– Properties are ______________________
• Always a ___________
• 2 or more _____________combined substances
(elements/compounds)
22. MATTER
No Is it uniform Yes
throughout?
No Can it be separated yes
by physical means?
No Can it be decomposed yes
into other substance by
a chemical process?
23. 3 Types of MIXTURES
Solution Colloid Suspension
Particle Type
Particle Size
Scatter Light?
(TYNDALL EFFECT)
Settle while
Separate by