Lesson 2.2 States of Matter
Overview
This lesson deals with the different states of matter and
the kinetic theory. On completion of the lesson, you
should be able to discuss the differences between solids,
liquids, gases and plasma. You should be able to use the
kinetic theory to describe changes in state and the
latent heats of fusion and vaporization.
 MINI LAB
CHOICE
OF ACTIVITIES
1) Boil water starting
with crushed ice.
EXPERIMENT
#1 Changes in Phase
Purpose: To show that the temperature of a substance
remains constant while it changes from solid to liquid
and from liquid to vapor.
Equipment:
Heat resistant container (beaker)
Hotplate or bunsen burner with stand
Thermometer
Stopwatch or clock
Procedure:
- Place some crushed
ice in a container and heat the container
- Measure and record
the temperature at regular intervals (say every
30 seconds)
- Allow the water in
the container to boil for 3 to 5 minutes
- Draw a graph of the
change in temperature with time
Question
Why did the temperature remain constant while the ice was
melting and also while the water was boiling?
Matter & Particles
Matter is made up of particles. These particles have
internal energy. The structure and movement of the
particles affects the properties of materials.
Four States
Matter can exist in four states: solid, liquid, vapor and
plasma.
We’re not too familiar with plasma. On earth, almost
everything consists of solids, liquids and gases but
plasma is the stuff that stars are made of and plasma
fills 99% of the universe.
Changes In State
All matter consists of particles. These particles are
constantly moving. There are also forces of attraction
between the particles and if they get too close together,
forces of repulsion become stronger.
Material particles are in constant motion - this affects
the forces of attraction and repulsion between the
particles. The faster they move (vibrate) the weaker the
net attraction between particles.
Bonds
The net effect of the forces of attraction and forces of
repulsion between particles is referred to as the degree
of bonding. In solids, the bonds are more or less
permanent whereas in liquids and gases, the bonds are
weaker and temporary.
Temperature
We know when something is hot or cold or hotter or colder.
Temperature is a measure of the degree of hotness that we
can measure with an instrument.
We also know that the particles that make up matter are
constantly moving. These particles move faster when they
get hotter. Many thermometers use the expansion of a
liquid into a narrow tube (capillary) to indicate the
rate at which particles are hitting the surface of the
thermometer bulb. The higher the temperature, the faster
the particles collide with the bulb and transfer energy
to the liquid in the bulb.
Solids
The particles that make up solids have bonds that keep
them from moving about. When these particles get more
energy, the bonds are not strong enough to stop the
particles from moving apart and the bonds break.
Liquids
There are still forces of attraction between the liquid
particles and these hold the liquid together but cant
stop the liquid particles migrating inside the liquid.
Liquids have weaker bonds and can move about (migrate) to
a limited extent. This allows liquids to take the shape
of the bottom of their container.
Gases
If the liquid particles gain energy, the bonds become
even weaker and the particles escape from the liquid and
become part of a gas. Gas particles have so much energy
that the net force of attraction between them is very
small. They also collide with each other quite easily and
move as far apart from each other as they can. A gas will
fill whatever container it is confined to. The only
reason why gases in the atmosphere don’t go off into
space is that the gas particles have mass and gravity
keeps them close to the earth.
Solutions
Solvents, like water, can break the bonds between solid
particles and draw the solid particles into the liquid
phase. The forces between solvent particles and the
material they dissolve are stronger than the forces that
hold the solid together. Many solids dissolve faster if
the liquid is heated and many solids will come out of
solution if the liquid is cooled.
Questions
- Does the Kinetic
Theory assume that all matter is made up of
particles that are constantly moving?
- How does heating a
material affect the movement of its particles?
- Are there forces of
attraction between particles in the solid,
liquid, gaseous and plasma phases?
- Why are the forces of
attraction between particles of a material in the
liquid phase weaker than those between particles
of the same material in the solid phase?
- Is it possible to
heat a partially molten solid without increasing
its temperature?
- Why does the
temperature not increase when a heated solid
melts?
Provide the missing words:
- The quantity of
energy needed to convert 1 kg of a solid to
liquid at the same temperature is known as
……………………………….
- The quantity of
energy needed to convert 1 kg of a liquid to
vapor at the same temperature is known as
……………………………….
- …………….
are compressible.
- ……………..have
much higher densities than gasses.
- ………….…
usually have higher densities than the
corresponding liquid.
- …………….
has a higher density in the liquid phase at 0ºC
than its solid at 0ºC.
- …………….
mix easily with one another.
- …………….
expand to occupy the available volume and take
the shape of the container.
- The shape of a
…………. can easily change but
its volume does not.
- The shape and volume
of a …………. does not easily
change.
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