Chapter 3 States of Matter
Solids, Liquids and Gases
3.1
States of Matter
Imagine that you have a baseball and a small packet of
ketchup.
1. If you squeeze the ketchup packet, how would it
change?
The shape of the packet would change.
2. If you squeeze the baseball, how would it change?
The baseball would not change shape in any noticeable
way.
3. What would these results tell you about the
properties of solids and liquids?
You may say that solids have a shape that doesn’t
change under ordinary circumstances but that a liquid can
change shape (flow) as the shape of its container changes.
Describing Matter

Materials can be classified as solids, liquids
or gases based on whether their shapes
and volumes are definite or variable.
◦ Shape and volume are clues to how particles
within something are arranged
Solids

What do a pencil, quarter, book or
cafeteria tray have in common?
◦ A recognizable shape and they take up a
certain amount of space.
◦ They are all in a solid state

Solid is the state of matter in which
materials have definite shape and volume.
◦ Definite means that the shape and volume
won’t change (as you move it) but obviously a
pencils changes shape if you sharpen it
Liquids

Demo
◦ Appearances are deceiving
A liquids always has the same shape as its
container and can be poured from one
container to another
 A Liquid is the state of matter in which a
material has a definite volume but not a
definite shape.

Gases

What are some different gasses that you
know?
◦ Air is a mixture of gases
◦ Natural gas or butane

Gas is the state of matter in which a
material has neither a definite shape nor
volume.
◦ A gas takes the shape and volume of its
container.
Atoms


The ‘shape’ and
‘volume’ of the Helium
in the balloon is the
same as the balloon
itself.
The Helium atoms in a
balloon are not
arranged in a regular
pattern.
◦ They are spaced
randomly throughout
the balloon.
Arrangement of atoms in solids,
liquids and gases
Other states of matter
On earth, almost all matter is a solid, liquid or gas
 Other places in the universe, matter exists in
other states.
 At extremely high temperatures, matter can exist
as plasma. (Such as on the Sun)
 Einstein also predicted a fifth state of matter that
would exist at extremely low temperatures (273C).

◦ Groups of atoms would behave as a single particle
◦ Scientists were able to replicate this temperature ad
found there was a 5th state of matter called the BoseEinstein condensate (BEC)
Kinetic theory
Why is copper normally a solid, mercury a
liquid and helium a gas?
 Because the particles inside are moving at
different rates – with different amounts of
kinetic energy
 Kinetic Energy is the energy an object has
due to its motion

◦ The fast an object moves the greater is kinetic
energy. (What kind of proportion is this?)
◦ The Kinetic theory of matter says that all
particles of matter are in constant motion.
Behavior of Gases

The motion of particles in
a gas are similar to the
motion of balls in a game of
pool. The ball moves in a
straight line until it strikes
another ball. Both balls
change course. Kinetic
energy is transferred during
those collisions.
Motion in Gases
The particles in a gas are ever at rest.
 Average speed of particles in a gas is
1600km/hr
 Particles are not all moving at the same
speed, some are slower and some faster
 What can happen to the kinetic energy of
2 He atoms when the atoms collide?

◦ one atom may gain kinetic energy and speed up
while the other atom loses kinetic energy and
slows down.
Behavior of Liquids

Do particles in liquids have kinetic energy?
◦ Yes! So- why does mercury have a definite volume at room
temperature instead of expanding to fill its container?
 The average speed of a mercury (HG) atom is much slower than the
average speed of a helium atom.

The particles in a liquid are more closely packed than the
particles in a gas.
◦ Think of going through the hallway before the bell rings and
after the bell rings – which can you do faster?
◦ A liquid takes the shape of its container because particles in a
liquid can flow to new locations.
◦ The volume of a liquid is constant because forces of attraction
keep the particles close together.
 Therefore, particles in a liquid cannot spread out and fill the container
Behavior of Solids

What is it like in a movie theater?
◦ Each person remains in the same location- a
‘fixed’ location and the total volume does not
change
This is what solids are like
 Solids have a definite volume and shape
because particles in a solid vibrate around
a fixed location.
 Lab Oobleck

The Gas Laws

3.2
3.2 The Gas Laws

What happens when you shake up a soda?
◦ It builds up pressure- but where does the
pressure come from?
◦ CO2 gas is released as you shake it up

Pressure is the result of a force distributed
over an area.
◦ when you shake up the soda bottle, pressure
builds up and causes a force to be distributed
over the area inside the bottle
Pressure

The SI Unit of pressure comes from the
units for force and area.
◦ Force is measured in newtons (N)
◦ Area is measured in meters (m2)
When a force in newtons is divided by an
area in m2, the unit of pressure is newtons
per square meter (N/m2)
 the pascal (Pa), is shorthand for N/m2

◦ A pascal is very small, so in science we often use
kilopascals (kPa)
Pressure

Gas pressure is produced by particles colliding
with the walls of a container (like a balloon)
When so many particles collide with the
walls of the container simultaneously, they
produce a measurable pressure.
 Collisions between particles of a gas and
the walls of the container cause pressure
in a closed container.

What do you think happened here?
A real example of where a ‘can’ gets crushed by air pressure!
The tanker was carrying hydrocarbon fuel – why do you think it
crushed after being emptied and then being transported up a
mountain? What affects can effect Gas Pressure?
Factors that Affect Gas Pressure


What are the particles of a gas doing?
What factors could affect those particles?
How else could gas pressure be affected?
◦ Particles could move faster or slower
◦ you could move the gas from a larger container
to a smaller one
◦ You could add or remove gas from the container

Factors that affect pressure in a closed
container are: temperature, volume, and
the number of particles.
Temperature
Raising the temperature of a gas will
increase its pressure if the volume of the
gas and number of particles are constant.
 If the temperature goes up the average
kinetic energy goes up and the particles
move faster.
 The particles collide with the wall of the
container more often and with more
force, increasing the pressure.

Number of Particles
Increasing the # of particles will increase
the pressure of a gas if the temperature
and volume are constant.
 What happens if you keep blowing air
into a balloon?

Volume
Reducing the amount of volume of a gas
increases its pressure if the temperature
of the gas and number of particles are
constant.
 If I have the same amount of particles in a
smaller container, will the pressure be
increased?

Example





Volume and Pressure are factors when you breathe
As you inhale, the diaphragm contracts causing your
chest cavity to expand.
This increases the volume and allows the particles in
air to spread out, lowering the pressure in your chest.
The pressure outside your body is now greater than
inside and air rushes into your lungs.
How does the movement of your rib cage affect your
chest cavity?
◦ The volume increases as the rib cage is lifted up and out.
The volume decreases as the rib cage moves down and in.
Gas Laws

There are several gas laws that describe
the behavior of gas.
◦ Boyle’s Law, Charles’s Law and the combined
gas law.
◦ We also have 4 variables that we use when
describing gases:




Temperature (T)
Pressure (P)
Volume (V)
And the amount of gas which is expressed in
number of moles (n)
Charles’s Law



Jacques Charles (the
inventor of the hydrogen
balloon) studied the behavior
of gases.
He discovered that when he
graphed volume vs.
temperature of gases that as
the volume of a gas increases,
the temperature of the gas also
increases.
Charles’s law states that the
volume of a gas is directly
proportional to its temp in K if
the pressure and number of
particles is constant.
The mathematical expression is
V1 = V 2
T1 T2
Boyle’s Law



P1V1=P2V2
Robert Boyle described
the relationship between
pressure and volume.
If the volume of a
cylinder is decreased, the
pressure increases.
Boyle’s Law states that
the volume of gas is
inversely proportional to
its pressure if the
temperature and number
of particles are constant.
The Combined Gas Law
Boyle’s Law and Charles’s Law can be
combined to form one law called The
Combined Gas Law
 This law describes the relationship
between temperature, volume and
pressure of a gas.
 The combined gas law can be used to
solve problems involving gases.

The Combined
Gas Law
Section 3.2
The Combined
Gas Law
Section 3.2
The Combined
Gas Law
Section 3.2
The Combined
Gas Law
Section 3.2
Math Practice
Pg 80 1, 2 and 3.
 Don’t forget temperature conversions!
