1. The Particle Model & Changes of State
Topic 5

2. Heat Capacity Capacity
the ability to receive or contain: This hotel has a large capacity.
the maximum amount or number that can be received or contained; cubic contents; volume: The inn is filled to capacity. The gasoline tank has a capacity of 20 gallons.

3. Heat Capacity
The amount of thermal energy (heat) that warms or cools an object by 1˚C
It describes a particular object
It depends on the mass of an object and the material it is made of
Heat Capacity

5. Specific Heat Capacity
The amount of thermal energy (heat) that warms or cools 1g of a material by 1˚C
It describes a specific material
It depends only on the material the object is made of
Specific Heat Capacity

6. Specific Heat Capacity

7. Heat Capacity

8. Think About it!
Do you think it is possible to boil water in a plastic bag?
Survival 101

9. Changes of State
As particles speed up and slow down, they will change state after a certain point
Solid  Liquid  Gas
Ice  Water  Steam

10. Changes of State
freezing

11. Changes of State
Different substances require different temperatures or amounts of pressure to change state
Changes of state are reversible under the right conditions
Baking a liquid batter into a solid cake is not a change of state, it cannot be reversed

12. Melting & Boiling
When energy is added to a substance the particles speed up
Melting is a solid to a liquid
Ice to water
Boiling or Evaporation is a liquid to a gas
Water to steam

13. Melting & Boiling
All pure substances have melting and boiling points (p.221)
Many substances have combustion points that prevent melting – like wood
Most substances are gases or solids at regular atmospheric temperatures
Many substances are not stable in liquid state

14. Melting & Boiling Points

15. Condensation & Freezing
When energy is removed from a substance the particles slow down
Condensation is a gas to a liquid
Drops of water forming on the outside of a cold glass
Freezing is a liquid to a solid
Water to ice

16. Sublimation & Deposition
When a substance is unstable as a liquid it may change state from solid to gas and gas to solid
A solid to gas is Sublimation
Dry Ice to gas
A gas to a solid is Deposition
Water vapor to frost on a window

17. Liquids Particles in liquids move very quickly
As high energy particles escape the liquid, the average energy decreases, cooling the liquid

18. Liquids Evaporation cools the surface the liquid is on
This process is called evaporative cooling
Evaporative cooling is useful for:
Joggers cooling as sweat evaporates
Water cooling a roof on a hot day
A wet cloth on a forehead for a fever
Kangaroos
BUT: Hypothermia can happen because of it!

19. Changes of State
Super-cooled Beer

20. Transferring Energy
Topic 6

21. Energy Transfer Energy can be transferred 3 ways: Radiation Conduction
Convection
BY SONG!

22. Radiation
This is the transfer of energy without the movement of particles
This is also called Electromagnetic Radiation (EMR)
Radiant energy travels in waves
It can pass through space, air, glass and many other materials

23. Radiation – EMR Spectrum

24. Radiation
All radiant waves travel very fast across empty space – at 300million m/s
Radiant energy travels in a straight line
Most radiation that we are exposed to is natural.
Slip Slop Slap
Radiation (the radioactivity) can be detected, measured and controlled

25. Radiation
Light waves and radiation waves will travel until they hit something that will:
Absorb
Let the radiation get part way into an object, often as heat
Transmit
Allow the radiation to pass through, without absorption
Reflect
Cause the radiation to bounce off

26. Radiation - Absorption
Dark coloured surfaces:
absorb radiant energy when they are cool
give off radiant energy when they are hot
Light coloured or shiny surfaces do not effectively absorb or give off radiant energy
Can you think of animals adapted with this in mind?

27. Radiation - Absorption
Radiant emission (giving off) of energy depends on surface area
Animal adaptations show this:
Desert animals have large ears to release heat
Killer whales have simple bodies and small limbs to keep heat in
Polar bear has black skin to absorb radiant energy with transparent hair that transmits ultraviolet radiation to the skin

28. Conduction Conduction is the transfer of energy through solids
Direct collisions between particles pass energy through the objects
The space between particles in a solid determines how fast energy is conducted

29. Conduction
Metal particles are often very close together, they conduct well
Wood, plastic and glass particles are further apart and are poor conductors – called insulators
A metal wire will conduct, but is wrapped in plastic to insulate it

30. Convection The transfer of energy in fluids
It follows a circular pattern called a convection current
As fluid particle heat up, speed up, and spread apart, they become lighter and rise
Once further from the heat, the particles cool and fall

31. Convection
Convection in the atmosphere causes thermals which birds and gliders use to soar, they also cause turbulence on planes
Convection ovens cook more evenly by circulating heat

32. Convection Currents

33. Convection Currents

34. REMEMBER: Energy can be transferred 3 ways: Radiation Conduction
Convection
BY SONG!
Heat energy always flows from the warmer to cooler object or substance

35. Think About it! Conservation of Energy
Energy cannot be created or destroyed
Energy can only be transformed from one type to another, or passed from one object, or substance, to another
Turn to p.232: follow the transfer of energy

36. Energy Transfer Energy in her fist transferred to the ball
The ball transferred energy to the floor.
Conduction occurred, when the energy in her fist was conducted by the particles in her fist to the particles in the ball.
The particles in the ball conducted the energy to the particles in the floor.
The particles in the air were also warmed by the flight of the ball and the particles transferred this energy by convection currents which were created in the air. CREATE AN ENERGY FLOW SYSTEM

37. Energy Systems All Energy Systems have 5 features: Energy Source
Energy can be mechanical, chemical, radiant, nuclear or electrical
Direction of Energy Transfer
Energy moves from high to low concentration
Transformations
Energy changes form as it is transferred
Waste Heat
Most energy is transferred, but some is always lost to surroundings
Control Systems
A device to start and stop the transfer of energy