Soda
Salt water
Soup
Mixtures
Coffee
Fog
Salad
dressing
A mixture is material made up of two or
more substances that are not chemically
combined. Each substance in the mixture
keeps its own properties.
Ex. salt water, pizza
Mixtures can be separated with physical
processes. These include filtering,
separating by distillation (salt water) or
machines such as the centrifuge (blood).
Separation can also occur using density,
melting, freezing, and magnetism.
Mixtures do not always contain the same
amounts of different substances.
(They do not have set ratios.)
Mixtures
Compounds
can be made of elements,
made of elements
compounds, or both
keep their original properties lose original properties
separated by physical means separated by chemical
means
formed using any ratio of
formed using a set mass
components
ratio of elements (like H2O)
A solution is a mixture that appears to be a
single substance but is made of particles of
two or more substances that are evenly mixed.
The particles are so small they cannot be seen
and they never settle out.
Another name is a homogeneous mixture
because they have the same appearance and
properties throughout. Ex. salt water,
vinegar, cake, iced tea, stainless steel, brass.
The solute is the substance being
dissolved (like sugar in coffee).
The solvent is
the substance in
which the solute
is dissolved
(coffee).
Salt is the solute and water is the
solvent in salt water.
Concentration is a measure of the
amount of solute dissolved in a
solvent. Concentration can be
expressed in grams of solute per
milliliter of solvent.
Solutions can be
described as concentrated
(lots of solute) or dilute
(a little of solute).
Solutions can be saturated, unsaturated
or supersaturated.
A saturated solution contains all the
solute it can at a given temperature.
An unsaturated solution contains less
solute than it can hold at a given
temperature. More solute can be
dissolved into an unsaturated solution.
A supersaturated solution is forced to
contain more solute than its normal
saturation level.
Solubility is the amount of solute needed
to make a saturated solution given the
amount of solvent at a given temperature.
Solubility is usually expressed in grams
per 100 mL of solvent.
The solubility
of KNO3 is
250 g at
100°C.
There are three methods to help solids dissolve
faster including: mixing by stirring or shaking,
heating, and crushing.
Gases dissolve faster
when they are cooled.
A suspension is a mixture where particles
are throughout the liquid but are large
enough to settle out.
The particles are insoluble so they
do not dissolve in liquid or gas.
Suspensions are heterogeneous mixtures
because the different parts can be easily seen.
Ex. muddy water, salad dressing, some
liquid medicines (“shake before using”).
The particles of a suspension are large
and scatter or block light so they are
difficult to see through.
If it sits undisturbed,
the particles will
settle out like a snow
globe.
A suspension can
separated with a filter.
A colloid is a heterogeneous mixture in
which particles are spread throughout
but are not heavy enough to settle out.
The particles are relatively small
and fairly well mixed.
Ex. fog, jello, milk, smoke,
mayonnaise, stick deodorant.
The particles of a colloid are smaller than a
suspension, but these particles still scatter a
beam of light when shined through.
A colloid cannot be separated with a filter.
The Tyndall effect is the
scattering of light by particles in a
mixture. The Tyndall effect can be
seen in all colloids. (Remember
that colloids have invisible
particles that never settle out.)
Fog scatters light.
Both the yellow and red
liquids at left look all
the same.
The yellow solution
does NOT scatter the
light, but the red colloid
scatters the light.
Smog is a form of air pollution. Smog is a
colloid of small, invisible pieces of solid
materials mixed with the gases that make up air.
Smog has many natural causes like forest fires,
volcanic eruptions, wind and dust. The major
cause of smog today is the unburned particles
in automobile exhaust.
Other causes of smog:
gasoline stations & industrial plants
hair sprays & spray paints
wood-burning stoves & fireplaces
Solubility Graph Notes
Remember: on the line – saturated
below the line – unsaturated
above the line - supersaturated
1) How many grams of sodium chlorate dissolves at 60ºC? 160 g
2) At what temperature does 40g of sodium chloride dissolve? 80ºC
3) Would 120g of potassium bromide at 80ºC form a saturated,
unsaturated or supersaturated solution? supersaturated
4) Would 80g of sodium nitrate at 20ºC form a saturated,
unsaturated or supersaturated solution? unsaturated