Transcript Chapter 9 Section 1

Chapter 9 Section 1
Temperature and Thermal Energy
Kinetic Theory of Matter
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Describes the motion of the particles
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Matter is composed of particles that are atoms,
molecules or ions
These particles are always in random motion
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Moving at different speeds in all directions
Because particles are in motion, they have kinetic
energy.
Temperature
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Measures the average kinetic energy of its
particles
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As the movement increases, the temperature
increases
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Temperature Scales
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Kelvin
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Celsius
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SI unit for temperature
Subtract 273 from Kelvin to get Celsius
Fahrenheit
Thermal Energy
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The sum of potential and kinetic energy
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Particles have potential energy because
molecules exert attractive forces on each other
As particles get further apart, the potential energy
increases
The thermal energy of an object changes when its
temperature changes
Heat
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Heat is the thermal energy that flows from
something at a higher temperature to
something at a lower temperature
Specific Heat
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Specific heat is the amount of thermal energy
needed to raise the temperature of 1 kg of
some material by 1 Degree C
Different materials have different specific
heats
Measuring Specific Heat
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Specific heat of a material can be measured
using a calorimeter
An instrument for measuring the amount of
heat released or absorbed in physical and
chemical processes.
Chapter 9 Section 2
States of Matter
Five States of Matter
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Solid
Liquid
Gas
Plasma
Bose-Einstein
Condensate
Solid
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Particles are packed closely together
Particles constantly vibrating in place
Attraction between particles are strong
Solids have fixed volume and shape
Liquid State
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Attractive force between
particles are weaker than in
a solid, but are strong
enough to cause particles to
cling together
Particles can slide past each
other
Liquids flow and take the
shape of a container
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Liquids have a definite
volume but not a definite
shape
Gas State
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Particles are much farther apart than in a solid or liquid
Attractive forces are weak because the particles are far apart
Gases do not have a definite shape or volume
Gas containers contain mostly empty space
Gas particles spread until they are distributed evenly
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Diffusion
Table Activity
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Each table will be responsible for acting like
aq solid, liquid and gas.
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Solids- group stands close together
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Each person vibrating slightly
Liquids – Molecules flow around each other
Gases – Molecules bounce off each other quickly
Plasma State
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Most common state of matter in the universe
Matter consisting of positively and negatively charged particles
Does not have a definite shape or volume
Results from collisions between particles moving at such high speeds that
electrons are knocked from the atoms
Examples are lightning bolts, neon and fluorescent tubes, auroras
Bose-Einstein Condensate
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Observed in a lab in 1995
Near absolute zero, atoms meld together to
form a super-atom
Changing States
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Adding thermal energy causes a phase change
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Melting
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Solid to Liquid
Amount of energy required to change substance from solid to
liquid is heat of fusion
Freezing
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Liquid to Solid
Changing States
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Vaporization
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Boiling
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Liquid to Gas
Does not need to occur
through whole liquid
Liquid to Gas
Throughout the liquid
Specific temperature
makes the liquid boil
Condensation
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Gas changes to liquid
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http://phet.colorado.edu/en/simulation/statesof-matter
Heating Curve of a Substance
Chapter 9 Section 3
Transferring Thermal
Energy
Ways to transfer Thermal Energy
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Heat moves from a
warmer object to a
cooler object
Thermal Energy moves
from one object to
another
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Conduction
Convection
Radiation
Conduction
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Transfer of energy between colliding particles
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Faster moving atoms collide with slower moving particles
As these collisions continue, energy is transferred
Is transferred by collisions between particles, not by
movement of matter
Different materials conduct better than others
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Best thermal conductors are metals
Gases are poorer conductors than solids or liquids
Convection
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Transfer of thermal energy in a fluid by the
movement of fluid from place to place
As particles move faster, they tend to be
further apart
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This causes fluid to expand
Volume increases, but mass stays the same
Water is an exception
Convection Currents
Radiation
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Transfer of energy by
electromagnetic waves
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Can travel even when
there is no matter
present
When radiation strikes
a material, it can be
absorbed, reflected, or
transmitted through the
material
Thermal Insulators
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A material in which thermal energy moves
slowly
Gases are usually the best thermal insulators
because they keep convection currents from
forming
Chapter 9 Section 4
Using Thermal Energy
Heating Systems
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Forced Air Systems
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Radiator Systems
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Fuel is burned in furnace and heats air
Fan blows heated air
Closed metal container that contains water or steam
Water heated and sent through pipes
Closed system
Electric Heating Systems
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Converts electrical energy to thermal energy
Thermodynamics
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First Law of
Thermodynamics
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Increase in thermal
energy of a system
equals the work done on
a system plus the
thermal energy
transferred to the system
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Second Law of
Thermodynamics
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It is impossible for
thermal energy to flow
from a cool object to a
warmer object unless
work is done
Closed vs. Open System
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Open System
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Work is done across a boundary
Closed System
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No work done across a boundary and no outside
work done
Heat Engine
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Device that converts
thermal energy into
work
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Cars Engine
Only about 25% is
converted into work
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Internal Combustion
Engine
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Fuel burned in engine
chambers
– Cylinder moves a
piston up and down