Download Heat

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9.1
Energy Transfer and Transformations – What
is the role of energy in our world?
D 1.Describe the effects of adding energy to
matter in terms of the motion of atoms and
molecules, and the resulting phase changes.
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Matter: a physical substance that occupies
space and possesses mass.
◦ Distinct from mind, spirit and energy.
Energy: power derived from the utilization of
physical or chemical resources
Ex: light and heat.
 What
are the effects of energy on
a micro and macro level?
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Kinetic Energy- energy
a moving object has
because of its motion.
◦ Dependant on the
object’s mass and its
speed.
Potential Energystored energy an
object has due to its
position.
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Matter is made of particles (atoms and
molecules).
These particles are constantly in motion.
The speed that these particles are moving
determines the temperature of an object.
Temperature- a measure of the average
kinetic energy of the particles in an object.
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Three Scales:
Fahrenheit (˚F)
Celsius (˚C)
Kelvin (K)
Conversion Formulas:
˚C = (˚F - 32) x 5/9
˚F = (C x 1.8) + 32
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Heat- the total kinetic energy of the particles
that make up a substance.
Units- joules or calories (cal)
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When you add heat to an object, you are
adding energy to that object.
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The increase in kinetic energy causes the
object to expand.
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Heat flows from warmer to cooler materials.
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The rise in temperature is
dependant on the amount
of heat that is added to an
object.
Make a prediction:
What would happen if the
same amount of heat is
added to a small beaker
of water and a large
beaker of water?
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Specific Heat- the amount of heat that is
needed to raise the temperature of 1kg of a
material by 1˚C.
This measurement determines how things
conduct heat.
Example- Plastic has a higher specific heat
than metal which is why we use plastic
spoons when we cook.
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Thermal Energy- the sum of the kinetic and
potential energy of all of the particles in an
object .
The kinetic energy is the movement of the
particles that make up the object.
The potential energy is the energy stored in
the bonds that are holding the particles
together.
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Heat – the total KE of a material.
Temperature – the average KE of a material.
Thermal Energy – the KE and PE of a material.
Specific Heat - the amount of heat that is
needed to raise the temperature of 1kg of a
material by 1˚C.
True or False:
For any two objects, the one with the higher
temperature always has more thermal energy.
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Describe how the thermal energy of an object
changes when the object’s temperature
changes.
When heat flows between two objects, does
the temperature increase of one object equal
the temperature decrease of the other?
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There are four main
states of matter:
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Solid
Liquid
Gas
Plasma
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Solid- a substance with a
definite volume and
shape.
The particles are
vibrating in place, held in
place by attractions
between the particles.
Chemical and physical
properties of a substance
are determined by the
geometric pattern of the
molecules.
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Liquid- A substance with a
definite volume, but no
definite shape.
The particles in a liquid can
flow freely with in the
substance, but attractions
between the particles keep
them from escaping.
The liquid will take the
shape of its container.
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Gas- a substance
without a definite shape
or volume.
The particles in a gas
have very little
attraction for each other
and so they can move
about freely taking the
size and shape of their
container.
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Plasma- a high energy state of matter in
which atoms lose their electrons and exist as
electron free nuclei in a sea of electrons.
This requires temperatures greater than 1
million degrees Celsius.
Natural Plasmas exist as stars and can be
created for a brief time by very powerful
lightning bolts (1million + volts)
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Heating:
Adding heat to a substance causes its particles to
move faster. If there is enough energy they will
break the attractions holding them in that state
and move up to the next state.
Cooling:
Removing heat from a substance causes its
particles to slow down and allows the attractions to
begin to affect the particles drawing them together
into a lower state.
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During a phase change the temperature
remains constant, because the energy
changes are associated with making/breaking
attractions, not with particle movements.
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Melting Point- the temperature at which a
solid becomes a liquid.
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Freezing Point- liquid becomes a solid.
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Boiling Point- liquid becomes a gas.
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Triple Point- The temperature and pressure
at which the solid, liquid, and vapor phases of
a pure substance can coexist in equilibrium
Melting- a solid
becomes a liquid.
Freezinga liquid becomes a
solid.
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Vaporization- a
liquid becomes a
gas.
Condensation- a
gas becomes a
liquid.
Some materials can undergo a change in state
between the solid state and gaseous state
without becoming a liquid.
 Sublimation- a solid becomes a gas.
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Deposition- a gas becomes a solid.
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Was heat being added to the system during
the time that the temperature remained
relatively constant? How was the heat being
used during these temperature plateaus?
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During this experiment, heat was being
added to the system, but at times the
temperature remained relatively constant.
During this time the energy being added to
the system in the form of heat was being
used to break the bonds or attractions
between the molecules causing a phase
change.
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Was heat being added to the system during
the time the temperature was rising? How
was the heat being used at this time?
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During this experiment, heat was being
added to the system and the temperature of
the water was increasing. The energy being
added to the system in the form of heat was
increasing the kinetic energy, the motion of
the particles, making up the water.
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Take out your homework: Analysis Q’s and
Heating Curve/Phase Change Worksheet)
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On a piece of paper fill in the following…
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Your mood note. (I am… because…)
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What is radiation?
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Go to the board and fill in ONE of the answers to
the homework in the one of the two diagrams
provided.
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What did we learn during our last class
meeting?
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What is happening to the thermal energy on a
micro and macro level if the temperature of
the water is not increasing during segments
BC and DE?
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In order for a liquid to change to a gas, heat
is added to the substance causing the kinetic
energy of that substance to increase, allowing
the molecules to overcome the attractive
forces holding them together. Describe how
a gas changes to a liquid.
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Thermal energy is transferred from place to
place by…
Conduction
Convection
Radiation
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Direct transfer of heat from one place to
another resulting from molecular collisions.
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Conduction is:
- Most efficient in solids
- Least efficient in gases
- Does not take place in a vacuum
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Materials conduct things at different rates.
(specific heat)
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A material that is a poor conductor is a good
insulator.
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Transfer of heat due to currents set up in a
medium because of temperature differences.
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Density = mass/volume.
An object with more mass and less volume
has a higher density. Ex-gas
An object with less mass and more volume
has a lower density. Ex-solid
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occurs most efficiently in liquids and gases.
transfer materials through the environment
via:
- Weather patterns
- Ocean Currents
- Ocean/Land Breezes
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Transfer of energy by electromagnetic waves.
Electromagnetic Radiation
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This is the only type of heat transfer that can
pass through a vacuum.
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Radiation is the method of transfer that allows
the sun’s energy to reach the Earth.
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Dark colored, dull surfaces absorb radiant energy
and increase in temperature.
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Light colored, shiny surfaces reflect radiant
energy.
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The scientific method is a way to ask and
answer scientific questions by making
observations and doing experiments.
1.
Ask a Question
2.
Do Background Research
3.
Construct a Hypothesis
4.
Test Your Hypothesis by Doing an Experiment
5.
Analyze Your Data and Draw a Conclusion
6.
Communicate Your Results
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It is important for your experiment to be a
fair test. A "fair test" occurs when you change
only one factor (variable) and keep all other
conditions the same.
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The scientific method starts when you ask a
question about something that you observe:
How, What, When, Who, Which, Why, or
Where?
And, in order for the scientific method to
answer the question it must be about
something that you can measure, preferably
with a number.
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Rather than starting from scratch in putting
together a plan for answering your question,
you want to be a savvy scientist using library
and Internet research to help you find the
best way to do things and insure that you
don't repeat mistakes from the past.
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A hypothesis is an educated guess about how
things work:
"If _____[I do this] _____, then _____[this]_____
will happen."
You must state your hypothesis in a way that
you can easily measure, and of course, your
hypothesis should be constructed in a way to
help you answer your original question.
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You should repeat your experiments several
times to make sure that the first results
weren't just an accident.
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Once your experiment is complete, you
collect your measurements and analyze them
to see if your hypothesis is true or false.
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To complete your lab you will communicate
your results to others.
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Weather permitting we will conduct this
experiment Monday 9/26
You must come prepared with all of your
materials!
Once your experiment is complete, you can
cook food.
◦ Ex- marshmallows, ramen noodles, etc.
1.
Concentrating sunlight.
2.
Converting light to heat.
3.
Trapping heat.
4.
Greenhouse effect.