Post on 14-Dec-2015
Kinetic TheoryApril 18, 2023
ObjectivesHSW: 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:
KeywordsBoiling 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
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.
Water can be a solid, liquid or a gas
States of matter and temperature
Each change of state is given a different name:
solid liquid gasmelting
freezing
boiling
condensing
Changes of state
sublimation
reverse sublimation
melting
freezing
solid liquid
boiling
condensing
liquid gas
tem
per
atu
re
time
solid
liquid
gas
Changes of state – heating curve
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.
What is evaporation?
Evaporation is another method of heat transfer.
Practical time
• 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
AF1 – Thinking ScientificallyAF4 – Using investigative approaches
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