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P3 Thermal physics(Benjamin) (Kinetic model of matter (Explanations using…
P3 Thermal physics(Benjamin)
States of matters
State
Solid
Occupies a fixed volume
Has a fixed shape
Liquid
Occupies a fixed volume
Takes the shape of its container
Gas
Expands to fill its container
Takes the shape of its container
change of state
Condensing--from gas to liquid
Freezing--from liquid to solid
Boiling,Evaporation--from liquid to gas
Sublimation--from solid to gas
Melting--from solid to liquid
Deposition--from gas to solid
Melting point
A pure substance changes from solid to liquid at a particular temperature
Boiling point
A liquid changes to a gas at a fixed temperature
Thermal properties of matter
Thermal expansion: Most substances expand when they are heated
Liquids generally expand faster than solids
Gases expand faster still
Solid expand most slowly when they are heated
Temperature and temperature scales
Internal energy
is the total energy of all the particles
Temperature
is a measure of the average kinetic energy of the individual particles
The Celsius scale
0c--the freezing point of pure water at atmospheric pressure
100c--the boiling point of pure water at atmospheric pressure
Thermal processes
Convection
Convection is the heat transfer due to the bulk movement of molecules within fluids such as gases and liquids.
Radiation
All hot objects emit infrared radiation, part of the electromagnetic spectrum of waves.
Conduction
Conduction is the movement of heat from one side to another side that has a lower temperature when they are touching each other.
Insulaator
The heat travels no further
Kinetic model of matter
Arrangement of particles
Liquid
The particles are packed slightly less closely together
Gas
The particles are widely separated from one another
Solid
The particles are packed closely together
Movement of particles
Liquid
The particles are both vibrating and moving from place to place
Gas
The particles are moving freely about, bouncing off one another and off the walls of their container
Solid
They cannot move around, only a bit
Explanations using the kinetic model
Gases diffuse from place to place
Dissolved substances diffuse throughout a liquid
Solid retain their shape
Most solids expand when they melt
Gases fill their container
Lquids expand a lot when they boil
Liquid take up the shape of their container
Brownian
It happens because the moving particles are constantly buffeted by the fast-moving particles of the air
Evaporation
Observation
A liquid evaporates more quickly when it is speed out, so that it has a greater surface area
A liquid evaporates more quickly when a draught blows across its surface
A liquid evaporates more rapidly when it is hotter
Explanation
More of the particles of the liquid are moving fast enough to escape from the surface
More of the particles are close to the surface
A draught is moving air