Transcript 9/21 properties of matter ppt

Physical Properties
of Matter

You live in a huge universe of matter. Because
you cannot live without a sense of order. Our
sorting techniques are usually based upon what
we can detect with our senses. The
characteristics of substances we can note with
our physical senses are physical properties.
Just as you can recognize your friends by their
physical appearance, you can also recognize
matter by its physical appearance and
properties.

Physical Properties
a
property that can be determined without
changing the composition of the substance

Examples: color, odor, density, melting point,
boiling point
how to find the density of matter.
 the equation for density is:

 density
= mass (grams)
volume (mL or cm3)
mass = density x volume
volume = mass
density

The following is a list of other ways of
telling one form of matter from another.
 ductility:
The property displayed by certain
metals that enables them to be drawn out into
wires without breaking
 malleability: The property displayed by
certain metals that enables them to be
hammered, rolled out, shaped, etc. without
breaking
 hardness:
The property of an object that
resists being crushed or deformed
 brittleness: The property of an object that
can easily be broken or crushed into smaller
pieces under low pressure
 conductivity: The property of metals, some
metalloids, and ionic solutions that allow an
electric current to pass through them
 state or phase: form – gas, liquid, solid – in
which matter is found
 solubility:
The property of a substance that
allows it to dissolve
 melting point: The temperature at which a
solid changes to a liquid
 boiling point: The temperature at which a
liquid changes to a gas
The Separation of Matter

If you were to begin your study of chemistry by
looking at substances handy to you, you would
most likely encounter more mixtures than
anything else. In this section, we will discuss
several methods for separating mixtures. As
you read about each technique, see how many
uses you can identify for it. These are the
methods in which you will need to be familiar to
do the activities later in this course

Method #1:
Filtration
 is
a process of separating large solid particles from a
liquid by passing the components through a porous
material like filter paper.
 Filtrate:
The liquid that passes through the porous
medium
 Residue: the solid material that does not pass
through the porous medium
Example

In everyday use, substances are usually filtered
to remove undesirable particles. One familiar
example of filtration is the purification of water in
a swimming pool. This is done by continuously
pumping water through the pool's filter. As the
water passes through the filters, dirt and any
other types of debris that might be harmful are
removed. Another example is the filtration of air
in heated and air-conditioned buildings. The air
is filtered either by a filter on the furnace or in
the air intake system in a building in order to
cleanse the air impurities.

Method #2: Crystallization

is a process in which crystals are formed by
removing the liquid part by evaporation
(change from liquid to gas without adding
heat) or vaporizing (change from liquid to gas
with adding heat)
Example

Salts can be purified by dissolving them in
water, filtering the solutions, and then
crystallization. The liquid part of the
solution is evaporated or heated off and
the solid part (salt) remains. Salt has
been collected from the world’s oceans for
thousands of years using this technique.

Distillation is another important technique
used to separate both solid/liquid mixtures
and liquid/liquid mixtures. In simple
distillation of a solid/liquid mixture, the
liquid is removed from the mixture by
evaporation and then recollected by
condensation.

However, when you have a liquid/liquid mixture,
the mixture must be separated by a more
complicated technique called fractional
distillation. When the mixture of liquids is
heated, the liquid with the lowest boiling point is
distilled first. This liquid turns into a vapor (gas)
and flows out the distillation flask. As it enters
the condensing tube, it is cooled and condenses
back into a liquid. It is then collected in a
graduated cylinder. When the liquid is almost
completely evaporated the liquid with the next
lowest boiling point begins to distill. This
process continues until there is nothing, or only
solid impurities, left in the distillation flask.

Method #3:
 is
Distillation
a process of separating a mixture based on
different boiling points
 Vaporization: a change from liquid to gas at the
boiling point when heat is added
 Condensation: a change from gas to liquid at the
condensation point when heat is removed.
 Fraction: each different liquid that is separated out of
the mixture

You probably have watched an ink drawing
dissolve into a rainbow of colors when water has
fallen on it. When an ink drawing comes into
contact with water, the water will drag the
inkspot with it as it moves across the paper.
Some substances in the ink move more slowly
than others. We can apply this property to
separate the components of the mixture. The
result is that the ink separates into different
colors.

Method #4: Chromatography
a
technique used to separate and analyze
various substances in a mixture. The
separation occurs because the components
are not equally soluble in a solvent and the
components are not equal in size.
Chemical Properties of Matter

Chemical Properties:
A
property of a substance that is observed
when the substance undergoes a change in
composition
active: reacts vigorously with other materials
 inactive: does not react readily with other
materials
 inert: do not react under normal or ordinary
conditions

Changes in Matter

Now that we have learned the fine points
about physical and chemical properties,
we are going to look at two kinds of
changes – physical changes and chemical
changes.

Physical Changes:
 refers
to a change in appearance not
chemical composition of the substance
 Examples:
phase changes (s-> l -> g),
crushing, grinding, dissolving (solubility)

Is tearing a piece of paper a physical
change?
 YES

Why or why not?
 the
composition of the matter does not
change. It is a change in appearance only.

Is solid water (ice) changing into liquid
water a physical change?
 YES

Why or why not?
 the
composition of the matter does not
change. It is a change in appearance only.

Chemical Changes
 refers
to a change in the composition of the
matter......a new substance is formed
 Examples:
rusting of iron , combustion of a
candle, burning of gasoline to run a car

There are some key signs that you can
look for to determine whether or not a
chemical change has occurred. These are
as follows:
1. A gas is given off (BUBBLES) but not boiling
2. A precipitate (insoluble solid) is produced.....
appears cloudy
3. Water is produced ..... Cobalt chloride paper
turns from blue to pink
4. A color change could indicate a chemical
change but also may indicate only a physical
one
5. A temperature change may indicate a chemical
change but can also indicate a physical one