13 April, 2015
Kinetic Theory
Objectives
HSW: Use the kinetic theory to explain the different states of matter.
Candidates should be able to draw simple diagrams to illustrate the
difference between solids, liquids and gases.
HSW: AF1 – Thinking Scientifically
AF4 – Using investigative approaches
Used before in:
Will use again in: Lesson 2 –
Energy Transformations
PLTS: Independent enquirers: support conclusions, using reasoned arguments and evidence.
Used before in:
Will use again in:
Keywords
Boiling point, condense, evaporate, freezing point, melt, melting
point, sublimation
Learning Outcomes:
All students should be able to:
• Describe what happens at
melting/freezing and boiling point
• Label a general cooling curve.
Most students should be able to:
• Use the particle model to explain what is
happening at each point on the cooling curve
• Describe the difference between the
temperatures of substances at boiling and
evaporation point.
Some students should be able to:
Explain how evaporation makes a liquid cooler
States of matter and temperature
Water can be a solid, liquid or a gas

At a cold enough temperature, even substances that
are normally gases will become solid.

At higher temperatures, solids change to become
liquids or gases – as long as they do not catch fire
or break down.
Particles in a solid – animation
Particles in a liquid – animation
Particles in a gas – animation
Changes of state
Each change of state is given a different name:
sublimation
melting
boiling
liquid
solid
freezing
gas
condensing
reverse
sublimation
Changes of state – heating curve
boiling 
liquid  gas
melting 
condensing
solid  liquid
freezing
time
Changes of state activity
Changes of state – cooling curve activity
What is evaporation?
Evaporation occurs when the particles in a
liquid escape to form a vapour.
Evaporation can occur at any temperature but
it occurs most rapidly at a liquid’s boiling point.
The particles that escape take some energy from
the remaining particles and so the temperature
of the liquid falls.
Evaporation is another method of heat transfer.
Practical
time
AF1 – Thinking Scientifically
AF4 – Using investigative approaches
• Practical - Stearic Acid practical – follow
method teacher has shown you. (method on
next slide)
• Draw your own cooling curve in your book and
label each change of state
• Now complete a “triangle/arrow summary
diagram in books to show all changes of state
and Particle diagrams of solids/liquids/gases
Method
• Take a boiling tube of molten wax from the
water bath
• Place in a boiling tube rack
• Take the temperature of the wax every
minute recording the state of matter.
• Stop when the wax has been solid for 2
minutes with no temperature change
• Draw a cooling curve from your results
Plenary - Sublimation
Sublimation, reverse sublimation
OR: AB document link on page 127 opens a
CLOZE exercise covering the material
on page 126-127. There is also an AT
presentation with the answers.
Youtube video of sublimation of dry ice:
http://www.youtube.com/watch?v=J8mDGwf
-5x0