Chemical Interactions Cliff Notes for Investigation 4: Kinetic Energy…
Investigation 4 Goal: What happens to matter when it is heated and cooled?
Pre
Med
Post
I can…
I can describe the difference in particle movement between solid, liquids, and gases
I can use words and drawings to explain how particles in matter expand and contract
I can compare and contrast compression, contraction, & expansion
I can explain what happens to the particles in a substance as they gain or lose KE
Goal:
Students observe expansion and contraction of solids, liquids, and gases, and explain the behavior in
terms of kinetic theory – the motion of particles.
Objectives
Science Content
1. Kinetic energy is energy in motion
2. The particles in substance/matter gain kinetic energy as they warm, and lose kinetic energy as they
cool.
3. Matter expands when the kinetic energy of its particle increases; contracts when the kinetic energy of
the particles decreases.
Conducting Investigations
1. Heat and cool gas, liquid, and solid matter to observe expansion and contraction
Building Explanations
2. Discuss expansion and contraction in terms of what students can see and what students visualize
happening at the particle level.
3. Explain expansion and contraction in terms of kinetic energy
4. Relate expansion and contraction to real world events.
Readings
Particles in Motion 23-27
Expansion and Contraction pages
Multimedia – Fossweb.com
Particles in Solid, Liquid, and Gas
Part 1
When a balloon is placed over the mouth of a bottle, a volume of air is trapped
inside the bottle-balloon system (a closed system). If the bottle is placed in hot
water, the air inside is heated, the space between the air particles increases,
and the air expands. The volume of the trapped air increases; the increased
volume of air fills the bottle-balloon system.
When the same system is place in cold water, the air
in the bottle-balloon system cools, the space
between particles decreases and the air contracts, taking up a smaller amount of
space. The balloon deflates and sometimes is pushed (not sucked) into the bottle.
Students confronted the idea (misconception) the hot air rises…we turned the bottleballoon system upside down. Many, although not all, students predicted the balloon
would be pushed (not sucked) into the bottle. However, the balloon expanded as
before. Hot air expands in all directions– the space between the particles increases. This expansion makes the
volume of hot air we are dealing with lighter than surrounding air that is colder. Therefore, the colder heavier
air pushes the hotter lighter air up. There is a short video on the agenda page explaining how this works in a
hot air balloon.
Kinetic Theory: the idea that the particles that make up all matter is constantly moving. Kinetic energy is
energy of motion; anything moving has kinetic energy. Gas particle are always moving. Some particles move
faster and some particles move slower. The speed at which a particle move is directly related to the amount of
kinetic energy it has. Fast particles have more kinetic energy; slow particles have less kinetic energy.
Gas particles are always hitting other particles. Fast-moving particles hit other particles more frequently and
harder. Hard, frequent hitting pushes gas particles farther apart. When gas particles are pushed farther apart,
the volume of gas increases. The gas expands.
Expansion of gas is the result of increased kinetic energy of the gas particles
Heat is another form of energy; when heat energy is transferred from the hot water to air particles, the kinetic
energy of the air particles increases and the air particles speed up. When heat energy is transferred from the
air particles to the cold water; the kinetic energy of the air particles decreases and the air particles slow down.
 Heat  KE of particles  speed of particles and the substance expands
 Heat  KE of particles  speed of particles and the substance contracts
Part 2: Liquid Expansion/Contraction
Students use their ideas and observations of gas to predict compression, expansion, and contraction of liquids.
Liquid cannot be compressed nor expanded with force, for the most part. (chem4kids.liquids).
Students make a bottle-tube system. The place the water filled bottle-tube system in cold water, then hot
water. They observed the contraction and expansion of liquid water in response to cooling and heating.
Student then apply their understanding of kinetic theory to explain liquid expansion and particle movement in
gas, liquid, and solids.
Part 3: Solid Expansion/Contraction
Students observe a brass sphere-and-ring demo. At room temp, the sphere passes easily through the ring.
When the ring is cooled in ice water, and the sphere is heated, the sphere will not pass easily through the ring.
Students apply their understanding of KE to explain solid expansion and contraction.
Eureka video on Expansion and Contraction