P3 Thermal physics(Benjamin)

States of matters

Thermal properties of matter

Thermal processes

State

Solid

Liquid

Gas

Occupies a fixed volume

Expands to fill its container

Occupies a fixed volume

Has a fixed shape

Takes the shape of 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

Boiling point

A pure substance changes from solid to liquid at a particular temperature

A liquid changes to a gas at a fixed temperature

Kinetic model of matter

Arrangement of particles

Movement of particles

Liquid

Gas

Solid

Liquid

Gas

Solid

The particles are packed closely together

The particles are packed slightly less closely together

The particles are widely separated from one another

They cannot move around, only a bit

The particles are both vibrating and moving from place to place

The particles are moving freely about, bouncing off one another and off the walls of their container

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

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

Convection

Radiation

Conduction

Conduction is the movement of heat from one side to another side that has a lower temperature when they are touching each other.

Convection is the heat transfer due to the bulk movement of molecules within fluids such as gases and liquids.

All hot objects emit infrared radiation, part of the electromagnetic spectrum of waves.

Insulaator

The heat travels no further