Change of State
A change of state is the
conversion of a substance
from one physical form to
another
Water to….
Steam!
When matter changes state,
the components of the item
remains the same.
Can you think of a
type of matter that
changes state from
one form to another?
Energy and Change
of State
When a substance change state,
the energy of that substance
also changes.
The energy of a substance is
determined by the motion of its
particles.
Example:
gas-lots of motion=
lots of energy
The faster particles move, the
more energy a substance has.
This works in reverse too, The
slower particles move, the
less energy the matter has.
What happens to the
energy of molecules
when a liquid freezes?
Melting
Melting is the change of state
from a solid to a liquid.
Example: a candle melts into
liquid wax
The point where a solid turns
into a liquid is called the
melting point.
The melting point of a substance
will not change- no matter if you
have a pinch of sugar or a full
bag of it.
Melting can be called an
endothermic change because
energy gets absorbed by the
change of state.
Can you describe
another
endothermic
change?
Freezing
Freezing is the change of state
from a liquid to a solid.
Example: put liquid “pop-ice” in
the freezer- within a
few hours it will be a solid!
The point at which a liquid turns
into a solid is called the freezing
point.
Freezing can also be called an
exothermic change because energy is
removed by the change of state
Can you think of
another exothermic
change?
Vaporization
Vaporization is the change of state
from a liquid to a gas.
Boiling is when vaporization occurs
from boiling liquid.
Evaporation
is when vaporization
occurs at a surface
of a liquid below its
boiling point.
Pressure can affect the boiling
point and vaporization of a liquid.
The higher elevation you are, the
lower the boiling point will be of a
liquid.
Vaporization is an endothermic
change of state.
Condensation
Condensation is the change of state
from a gas to a liquid
Condensation can occur when you put a
cold lid on a pot of boiling water. It also
occurs when the mirror in your
bathroom steams up after a shower.
Condensation is an exothermic
change of state.
Why is condensation
an exothermic
change?
Endothermic
Heat Energy is required
Exothermic
Heat Energy is removed
Types of vaporization
Boiling
Occurs throughout liquid
Evaporation
Occurs at surface of liquid
Change of state From..to
Energy
Change of state From..to
Energy