Transcript Chapter Four

A Matter of Fact
Solutions, Suspensions and Colloids
What is a Mixture?
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Mixtures – two or more substances that
are not chemically combined with each
other and can be separated by physical
means. The substances in a mixture
retain their individual properties.
Two types:
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Heterogeneous Mixtures (cereal, salad)
Homogeneous Mixture (paint)
Two types of Mixtures
Mixtures
Homogeneous
Mixtures
Heterogeneous Mixtures
Solutions
Colloids
Alloys
Suspensions
Solutions
A type of homogeneous mixture
formed when one substance dissolves
in another.
 It is the best mixed of all mixtures.
 Same appearance and properties
throughout
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Solvent and Solute
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A solution always has a
substance that is dissolved
and a substance that does
the dissolving.
Solute -substance that is
dissolved
Solvent -substance that
does the dissolving
Animation of NaCl dissolving in
H2O
Dissolving a Salt.swf
Solutes
 Insoluble:
Unable to dissolve in
the solvent
 Soluble:
solvent
Able to dissolve in the
The Universal Solvent: Water
Water as a Solvent
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Many liquid solutions contain water as the
solvent.
Ocean water is basically a water solution
that contains many salts.
Body fluids are also
water solutions.
Concentration of a Solution
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Concentration is a measure of how much
solute is dissolved in the solvent.
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Concentrated Orange Juice
Concentrated Laundry Detergent
Opposite of concentrated is dilute.
Solubility
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The amount of solute that can dissolve in
a given amount of solvent.
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Solubility of solids in liquids increases with
temperature.
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Example: What happens if you add a lot of sugar to a
glass of iced tea?
You can add more sugar to hot tea than iced tea.
Solubility of gases in liquids decreases
with temperature.
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You can keep more bubbles in cold soda than warm
soda.
Speed up Dissolving?
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Mixing
Heating
Crushing
Solutions are made from solutes
and solvents from all states of
matter.
Example: Air is a solution of
oxygen and other gases (solutes)
dissolved in nitrogen (solvent).
Types of solutions
Solute
Gas
Solvent
Gas
Gas
Liquid
Solid
Liquid
Solid
Solid
Example
Air (oxygen in nitrogen)
Soda water
(CO2 in H2O)
Ocean water
(salt in water)
Gold jewelry (copper in gold),
brass, bronze, pewter, solder
Types of Solutions
Solute
Liquid
Liquid
Liquid
Solid
Solvent
Example
Gas
Humid Air
Liquid
Antifreeze
ethylene glycol in H2O
Solid
Dental fillings
Hg in Ag
Gas
Soot, dust in air
Alloys
Metals dissolved in metals are called alloys.
Stainless steel is a mixture
of iron and chromium.
Brass is an alloy of
copper and zinc.
Suspensions
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Suspensions are mixtures
containing large particles.
If you shake or stir a
suspension, the particles will
disperse, but will eventually
settle out or separate.
Particles of a suspension will
scatter light.
Colloids
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Colloids are mixtures containing
relatively large particles that do
not settle out.
The particles are dispersed
throughout the mixture, but are
not dissolved.
Particles of a colloid will scatter
light.
100
80
60
40
20
0
East
West
North
1st 2nd 3rd 4th
Qtr Qtr Qtr Qtr
Types of Colloids
Gas
Liquid
Liquid
Liquid
Gas
Liquid
Liquid
Solid
Solid
Solid
Gas
Liquid
Gas
Solid
FOAMS, whipped cream, mousse
FOG, Clouds
EMULSIONS:
Mayonnaise,oil,vinegar,egg yolk
butter and other gels
SMOKES, all kinds
SOLS, Paint pigment -many are
metallic - in H2O or oil
Marshmallows
Separation Techniques
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Magnets – based on
magnetism of the matter
Centrifugation – based on
densities of the matter
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Ex: blood is broken down into
red blood cells, platelets,
plasma
Chromotography
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Means “Color Writing”
It involves passing a mixture dissolved in
a mobile phase through a stationary
phase.
Components travel at different speeds
based on their size and therefore separate
along the way.
Separation Techniques
The Distillation Process
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Distillation is a process used to separate a
mixture into components based on boiling points
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Involves a change of state, usually from
liquid to gas, and then condensation to return
the now separated component to liquid state.
 The distillation apparatus (still) has three parts:
(1) A flask with an outlet tube,
(2) A condenser, and
(3) A vessel.
Distillation