Temperature

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Temperature Thermal Energy
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Temperature and Thermal Energy Key Ideas Three
temperature scales are Fahrenheit, Celsius, and
Kelvin. Temperature is a measure of the average
kinetic energy of each particle within an object.
Thermal energy is the total energy of the
particles that make up an object.
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What are the three common temperature scales?
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Temperature Scales Comparing and Contrasting What
are the differences among the scales?
Page 113
At what temperature does water turn to a solid
? (A) 32 K (B) 0 C (C) 273 F What
temperature would be a comfortable room
setting? (A) 150 F (B) 23 C (C) 273
K
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On which scale does absolute zero exist? (A)
Fahrenheit (B) Celsius (C) Kelvin   At
what temperature does water become water
vapor? (A) 199 F (B) 220 F (C) 60
C
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How does temperature differ from thermal energy?
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Thermal Energy A large pot of hot cocoa can have
the same temperature as a small cup of cocoa.
Comparing and Contrasting Do both containers
and the cocoa in them have the same thermal
energy?
Thermal energy does not depend on just
temperature and the number of particles in a
substance. It also depends on how the particles
are arranged.
How can you add thermal energy to matter without
increasing its temperature?
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Page 114
Which container has greater thermal energy? (A)
big pot (B) glass Which container will stay
warmer longer? (A) big pot (B) glass
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Interpreting Data Compare the average motion of
the molecules in the three containers. Drawing
Conclusions Compare the total amount of thermal
energy in the three containers.
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A. B. C.
In the diagram above, which container has the
fastest moving molecules? In the above diagram,
which container has the greatest thermal
energy? In the above diagram, which container has
the greatest temperature?
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g/cm3
This substance is denser.
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Thermal Energy and States of Matter Key
Ideas Matter can undergo a change of state when
thermal energy is added or removed. As matter is
heated, its particles move faster.
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Thermal Energy and States of Matter Matter can
undergo a change of state when thermal energy is
added or removed. As matter is heated, its
particles move faster.
States of Matter
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Changes of State
Matter will change from one state to another if
thermal energy is absorbed or released. Look at
the graph of changes of state. Thermal energy is
shown on the horizontal axis and temperature is
shown on the vertical axis. You can see that as
thermal energy increases, a substance changes
from a solid to a liquid and then to a gas. A
substance changes from a gas to a liquid and then
to a solid as thermal energy is removed from it.
Changes of State The flat regions of the graph
show conditions under which thermal energy is
changing but temperature remains the same. Under
these conditions matter is changing from one
state to another.
SolidLiquid Changes of State
LiquidGas Changes of State
Vaporization Condensation
Melting Freezing
When molten steel becomes solid, is energy
absorbed or released by the steel?
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• How does thermal energy produce a change from one
  state of matter to another?
• What happens to the temperature of a substance
  during a change of state? What happens to thermal
  energy during a change of state?
• Applying Concepts Why do cookbooks recommend that
  you poke holes in a potato before baking it?

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The Nature of Heat Key Ideas Heat is a transfer
of thermal energy. Heat is transferred by
conduction, convection, and radiation. The
amount of energy needed to raise the temperature
of 1 kilogram of a substance by 1 kelvin is the
specific heat.
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Conduction
Convection
Radiation
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• PAGE 323
• (bold sentence) Heat is transferred through
  radiation, conduction, convection
• Radiation- transfer of heat by electromagnetic
  waves does NOT need molecules in matter to be
  transferred.
• HEAT TRANSFER THROUGH SPACE
• (A) Suns energy to earth
• (B) Heat from lamp
• (C) heat from open fire

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RADIATION
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RADIATION
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Radiation
Drawing Conclusions In which location did your
hand feel warmer? Explain your observations in
terms of heat transfer.
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PAGE 324 CONDUCTION- Heat transfer through solids
by direct contact of particles or molecules (A)
Heat from fire to end of metal (B) Heat from
bottom of pot to handle
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Conduction
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CONDUCTION
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Conduction
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CONDUCTION
CONDUCTION
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Conduction
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Observing What happened to the butter? Did the
same thing happen on every utensil? How can you
account for your observations?
Only when thermal energy is transferred is it
called heat. Heat is thermal energy moving from
an object at one temperature to an object at a
different temperature.
So work and heat are both examples of energy
transfers. They are both measured with the same
unitjoules.
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CONVECTION- heat transfer through FLUIDS (liquids
gases) involving movement of fluids DENSITY Heat
ed fluids rise when heated (less dense or lighter
molecules) Fluids cool (denser molecules) drop
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Convection
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Dense fluid SINKS
Lighter fluid RISES
2 CONVECTION CURRENTS-
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LIGHTER AIR-LESS DENSE
DENSE AIR
Convection
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HEAT IS RISING FROM THE CORE.
Convection
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Conductors and Insulators
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Slowing Heat Transfer Double-pane windows and
thermos bottles use air or a vacuum to slow the
transfer of heat.
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• QUIZ CONVECTION, CONDUCTION, RADIATION
• SPOON-
• OCEAN-
• SUN TO EARTH-
• ROOM AIR-
• BOILING-
• LAMP TO FOOD-
• MAGMA-

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• ANSWERS TO QUIZ CONVECTION, CONDUCTION,
  RADIATION
• SPOON- cond
• OCEAN- conv
• SUN TO EARTH- rad
• ROOM AIR- conv
• BOILING- conv
• LAMP TO FOOD- rad
• MAGMA- conv

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Page 117
In the above diagram how does the water become
heated? (A) conduction (B) convection
(C) radiation In the above diagram what happens
to the heated water from the bottom of the pot? (
(A)  Heated liquid rises to the top then loses
heat energy drops (B) Heated liquid drops to
the bottom loses heat energy then rises to the
top
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Specific heat
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VOCABULARY 1. Specific Heat- The specific heat of
a substance tells how much energy is needed to
raise the substances temperature by a given
amount. Unit of measurement for specific heat
is (J / g C). Sometimes the unit J/ kg-K is
used.

Every
substance has its own specific heat capacity. 2.
Joules- the unit of measurement for energy . 3.
To find the Specific heat of a substance use the
formula Joules divided by the grams multiplied
by the difference between starting temperature
ending temperature Joules / grams X C
(J / g ?C) 4. density-
Density is a measure of how much mass is
contained in a given unit volume (density
mass/volume). It is usually expressed in g/cm3 or
g/mL. Put simply, if mass is a measure of how
much stuff there is in an object, density is a
measure of how tightly that stuff is packed
together. 5. mass- the property of a body that
causes it to have weight in a gravitational
field 6. Heat flow- the transfer of energy from
a warmer object to a cooler object
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Page 120
Problem Solving How much more energy is required
to raise the temperature of 1 kg of iron than is
needed to raise the temperature of 1 kg of copper
by the same amount?
Problem Solving How much energy is gained by 10
kg of silver if it is heated from 21C to 35C?
Mass X Specific Heat X Temp difference
How much heat is needed to raise the temperature
of 5 kilograms of water 10 kelvins? You need
to transfer 209,000 joules to the water to
increase its temperature by 10 kelvins.
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Imagine running across hot sand toward the ocean.
You run to the waters edge, and stop shortthe
water is too cold. How can the sand be so hot and
the water so cold? The answer is that sand is
much denser than water. The molecules of sand are
closer together than molecules of water passing
the heat along to the other molecules faster.
Water requires more heat energy to raise its
temperature by 1 degree Celsius than sand.
Waters molecules are farther apart than the
sand grains so it takes time to pass along the
heat energy.
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If the same amount of heat is supplied to sand
and water of the same mass, which one would have
a larger change in temperature?
Why would there be a larger temperature
difference in one of the above substances? Refer
to the diagrams to the right.
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The interactive activity site is at the following
address http//www.sciencegeek.net/Shockwave/Speci
ficHeat.htm
Application of Heat energy
BEGINNING ROOM TEMPERATURE IS 20C (50
Joules per second) ENDING TEMPERATURE
IN C FOR 5 GRAMS OF SUBSTANCE
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Creating a column graph to show specific heat
comparisons Make a column (bar) graph for the
following data table.
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• According to the table, how much more energy is
  required to raise the temperature of 1 kg of iron
  than is needed to raise the temperature of 1 kg
  of copper by the same amount?
• 65 J/(kg K)
• 65 J/kg
• 65 kilograms
• 65 joules

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