Physical Properties of Matter and Mixtures
What is matter?
Matter is anything that has mass
and volume. All matter is made up
of very small particles too small to
be seen. Even though these
particles are very small, they give
matter its basic properties.
Solids, liquids, and gases can be
compared based on their physical
properties.
Solids have a definite shape and volume. The
particles in a solid are very close to one
another and vibrate, but stay in the same
place. The volume of a solid with a
rectangular shape can be determined by
multiplying the height x width x height. The
volume of an irregularly shaped solid can be
determined by water displacement in a
graduated cylinder. Water displacement is
when the cylinder is filled with water and measured. The object is placed
into the water filled cylinder and the water level is measured again.
Subtract the water level of the
cylinder from the water level
with the object and you have
the volume of the irregularly
shaped solid. The volume is
water displaced equals the
volume of the object.
Liquids have a definite
volume, but their shape
changes according to the
shape of their
containers. The particles
are close to one another,
but they are able to
move apart from each
other
and
flow
from place to place. The volume of a liquid can be
measured using a beaker, graduated cylinder, or
graduated syringe.
Gases have no definite shape or volume, but they take
the shape and volume of their containers, filling the space available. The
particles move far apart from each other and spread out through the
available space.
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Mixtures
Particles in Solutions
Mixtures are composed of two or more
substances that are mixed together, but can
be separated from each other. Mixtures can
be made from various combinations of
solids, liquids, and gases.
The substance in the solution that
has the greatest amount is the
solvent. It is usually the liquid. The
substance that has the least
amount is the solute. It is usually
the solid. In the glass of salt water,
the water is the solvent (there is
more water than salt), and the
Examples of mixtures of solids: trail mix, chef salad, a bucket of
gravel and sand
Examples of mixtures of solids and liquids: salt water solution, sun
tea, mud
Examples of mixtures of liquids: oil and vinegar salad dressing
Examples of liquids and gases: carbonated soft drinks
In mixtures, the substances do not
change permanently, they keep their
separate properties. For example, in
trail mix the pretzels stay salty and
brown and can be picked out of the trail
mix. The tomatoes in a chef salad
remain tomatoes, they remain red and
juicy, and you can pick them out of the
chef salad.
Solutions are a type of mixture. They are made up of substances that
mix so completely that they cannot be recognized as separate
substances, but, they can be separated back into separate substances.
Examples of solutions are
sun tea, flavored drink mix,
salt water, sugar water, and
indigestion medicine tablet
added to water.
solute is the salt (there is less salt).
Concentration of Solutions
The relationship of the amount of solute to solvent determines the
concentration of a solution. The more solute that is in the solvent, the
more concentrated it is said to be. For example, the more sugar you put
in a glass of water, the more concentrated it is. When two solutions
contain the same amount of solvent, the one with the most solute is the
more concentrated solution. In order to make a solution more
concentrated, more solute is added. To make a solution less
concentrated (diluted), more solvent is added. For example, if your
sweet tea isn’t sweet enough, you add sugar or sweetener to make it
more concentrated. If your tea is too sweet, you can add water to the
tea to make it less concentrated and it is not as sweet.
Rate of Dissolving
Different amounts of solutes
dissolve in solvents in solutions in
given times. This is called the rate
of dissolving. There are factors
which affect the rate of
dissolving:
Temperature change: If the
temperature increases, more of
the solute will dissolve faster. For example, more sugar will dissolve in
warm water than cold water.
Particle size: If the particle sizes are smaller, more of the solute will
dissolve faster. For example, powdered sugar dissolves faster than
granulated sugar because the particles are so small.
Stirring: If the solution is stirred, more of the solute will dissolve faster.
For example, when you put sugar in your coffee what do you do? You
stir it. This helps the sugar dissolve in the coffee.
Total mass of Mixtures
Matter can neither be created nor destroyed, but can be changed in
form. Because of this, the total mass of the materials before they are
mixed together is the same as the total mass of materials after they are
mixed together. For example, you combine ingredients (flour, baking
soda, salt, sugar, milk, eggs, and butter) to create pancakes. You do not
create more ingredients, you just mix them together and form a new
substance—pancakes. Sometimes is seems some mass is lost. When an
Alka Seltzer is mixed with water, the total mass will not equal, that is
because some of the mass has been changed into a gas. It has not
disappeared, it has become a gas and gone out of the glass.
Separating Mixtures- There are different ways to separate mixtures.
Type of separating
How it works
Real life example
Filtration
Used to separate solid particles from a liquid
Pour the mixture through filter paper. The solid
will stay in the filter and allow the liquid to pass
through.
Water treatment plants separate
dirt and other solid particles from
water to produce clean drinking
water.
Sifting
Separates smaller solid particles from larger
solid particles
Magnetic attraction
Used to separate magnetic material from a
mixture of other substances
A mixture with different sized solid particles
can be put into a container with a screen at the
bottom with holes.
When shaken, the smaller pieces will go
through the screen leaving the larger ones at
the top.
When a magnet is stirred through the mixture,
it pulls out the magnetic material from the
mixture.
Cooks sift flour to get a smaller
particle for baking.
Sand and gravel companies
separate rocks into different sizes
for road building and other
construction projects.
A cow magnet is given to the cow
to swallow. It stays in the first
stomach and catches magnetic
materials that could harm the cow
if it continued digesting.
Evaporation
Used to separate a solid that has dissolved
into a liquid solution
Heat the solution, or leave it uncovered, until
all the liquid turns to a gas (evaporates) and
leaves the solid behind.
Salt in ocean water is separated by
heating the solution until all the
water evaporates leaving the solid
salt in the container.
Chromatography
Used to separate and analyze the solutes in a
solution
A small amount of the solution is put on a piece
of filter paper and dipped into a solvent. The
substances in the solution that dissolve easily
will travel up the filter paper the furthest and
substances that do not dissolve easily do not
travel as far.
Scientists use this to identify
substances in a solution by
comparing the bands of colors on
different filter papers.
Floatation
Used to separate solids that float from the
remaining liquid in a mixture.
Solids are stirred and when they float to the
top they are skimmed off the surface of the
liquid and put into a different container.
Water purification plants use this
to purify water before the water is
released back into the water
source.