Matter: Physical and Chemical
Properties/Changes
Or BOTH!
Physical vs Chemical
When the change which has occurred does
nothing to change the chemical composition
of the substance, it is a physical change.
When the change which has occurred does
change the chemical structure (bonds are
formed, broken or both) then a chemical
change has occurred.
A physical change does not change the chemical
properties of the substance.
A chemical change does change the chemical
properties of the substance.
Physical and Chemical
Physical Change
• Changing the shape, size, or
phase of the material
• Warming it up and
spreading out the particles.
• This change can be undone.
Chemical Change
• The chemical structure is
not the same
• The properties of the
material (solubility,
flammability) have changed.
• This change cannot be
undone.
Was It a Chemical Change?
We look for five things (and we want to observe at
least two) to determine if it was a chemical
change.
1. Heat is given off (exothermic) or absorbed
(endothermic)
2. Fire
3. Light
4. Sound
5. Color Change (never enough by itself)
Properties
Properties are characteristics which are used to
identify something.
In chemistry, we have physical properties and
chemical properties.
Physical Properties
These are properties that describe the state of
the physical system. They include: mass,
length, solubility, density, boiling point, color,
density, conductivity, hardness, strength
Physical Properties
Physical Properties come in two forms
a. One that depends upon the amount of
material present (for example shape of
sample)
b. And one that is independent of the amount
(for example density)
• An intensive physical property is independent
of the amount.
• An extensive physical property is dependent
upon the amount.
A Chemical Property
It how the substance reacts when it forms a new
substance.
Examples include: combustion, reactivity in
water, flammability
Mixed
At times a property may have characteristics of
both chemical and physical changes.
An example is pH.
pH is the measurement of the concentration of
H+ ions in solution.
When an acid is added to water some or all of it
will break into ions. Only if the pH is changed,
it is truly a chemical change.
Uses of Chemical and Physical
Properties
Separations
Separations
A mixture is two or more different chemical
substances which are found in close proximity
to one another.
To separate a mixture, we generally take
advantage of physical properties (or mixed
physical and chemical properties)/
Distillation
The physical property used to separate is boiling
point. If the boiling point of the two
substances are fairly separate, this is easy to
do.
Needed materials: condenser, cold running
water, heat source, and a collecting beaker.
Solubility
Solubility is taking advantage of the
different substances that chemicals
may or may not dissolve in.
Needed Materials: solvent or solvents,
beaker
Chromatography is a method
that takes advantage of
solubility.
Magnetism
Some materials are magnetic and if they are the
only magnetic material in the mixture, it can
easily be removed.
Needed Materials: magnet and container
Density
Use different liquids to float or sink substances.
Materials needed: beaker or float pan and
liquids
Filtering
Using particle size
differences.
Needed Materials:
filters, funnel, flasks,
water for rinsing,
and wash bottle
One step in treating
municipal waste
Crystallization
This takes advantage of two
properties: solubility and freezing
point.
Need: one substance that is less
soluble in the liquid with the
higher freezing point
Needed Materials: liquid to dissolve,
ice bath, beaker
Sublimation
This separation technique
takes advantage of
different boiling and
sublimation
temperatures.
Needed materials: heat
source, watch glass,
beaker, and ice