Chapter: Energy061851f72b23d802adaa-d56582058559818728a814bdd94ad99a.r54.cf2… · Chapter: Energy...
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Chapter: Energy Table of Contents Section 3: Chemical Energy Section 1: Energy Changes Section 2: Temperature
Transcript of Chapter: Energy061851f72b23d802adaa-d56582058559818728a814bdd94ad99a.r54.cf2… · Chapter: Energy...
Chapter: Energy
Table of Contents
Section 3: Chemical Energy
Section 1: Energy Changes
Section 2: Temperature
• Matter – is everything that has mass and
takes up space
• Physical and Chemical properties of
matter can help us identify different
types of matter
• But what is matter made off ?
• Matter is made of atoms.
• Atoms are the basic building block of
matter.
• Atoms will arrange themselves in
molecules ( groups of atoms)
• EX of atoms: open book on the Periodic
table
The molecule of Water
Hydrogen and
oxygen are atoms
found in the
periodic table and
will combine to
make a molecule
of water
• What is that keep atoms together in
molecules?
• Energy
• So without energy there will be no matter
• But, there are different types of Energy!
• Energy is the ability to cause change.
• Ex: energy can change one molecule into another
• energy can change the temperature of a pot of water
• it can change the direction and speed of a baseball.
Energy—What is energy?
Energy Changes
1
• An energy transformation occurs if energy changes from one form to another.
Energy Transformations
Energy Changes
1
• Read book page 163
Using Energy Transformations
Energy Changes
1
The battery has
electrical energy
that the light bulb
will transform in
heat and light
• A moving ball has energy due to its motion.
Kinetic Energy
Energy Changes
1
• The energy an object has due to its motion is called kineticenergy.
• A ball in movement can cause change and energy is the ability to cause change
Kinetic Energy depends on:
Energy Changes
1
The amount of kinetic energy an object has depends on the mass and speed of the object.
The bigger the mass and the higher the speed, the higher the kinetic energy will be
• Kinetic energy can be transferred from one object to another when they collide.
Transferring Kinetic Energy
Energy Changes
1
*Potential energy is energy that is stored in an object because of the object’s position.
Potential Energy
Energy Changes
1
• When you raise an object above its original position, it has the potential to fall.
Potential Energy
Energy Changes
1
• To raise an object, you have to transfer energy to the object ( you have to use your energy to raise it)
• This energy becomes stored as potential energy.
**When an object falls Potential Energy
turns into kinetic energy.
*When the potential energy is at
its maximum, the kinetic energy is at its
minimum
Potential Energy
Energy Changes
1
• By using the ski lift to take her to the top of the hill, the skier increased her potential energy by changing her position.
Increasing Potential Energy
Energy Changes
1
*The higher an object is lifted above Earth, the greater its potential energy.
*The potential energy will depend on how higher an object is placed, compared to its original position
Converting Potential and Kinetic
Energy
• As soon as the skier starts going down
the hill, her potential energy starts
decreasing and her kinetic energy starts
increasing.
• One form of energy is being transformed
into another form of energy.
• Just like the skier going down a hill, the potential energy that water has at the top of a waterfall is transformed into kinetic energy as it falls downward.
Energy Changes in Falling Water
Energy Changes
1
Conservation of Energy
Energy Changes
1
• According to the law of conservation of energy, energy cannot be created or destroyed.
• It only can be transformed from one form into another, so the total amount of energy in the universe never changes.
Temperature—Temperature and Kinetic Energy
• Any material or object is made up of atoms or molecules.
• These particles are moving constantly, even if the object appears to be perfectly still.
Temperature
2
Temperature
2
• random motion - is the motion of particles in all directions in solids, liquids, and gases
• If the particles are moving, they have kinetic energy.
• The faster the particles are moving, the more kinetic energy they have.
Temperature and Kinetic Energy
• Temperature is the measure of the average kinetic energy of the particles in an object.
Temperature and Kinetic Energy
2
higher Temp. - more
movement of the molecules
– more kinetic energy
Mini Lab book
• We observed that the food dye spread
faster on the warm water than in the cold
water. Why?
Because in the warm water, the molecules have
more kinetic energy, move more and will
distribute the molecules of food dye faster
Heat
• Heat is the transfer of energy from one object to another due to a difference in temperature
2
• Heat flows from warmer objects to cooler ones.
• Look at Figure 14 page 172
Heat and Temperature
• The transfer of heat from one substance to another will depend on :
1) The amount of material in an object
2) The types of atoms the material is made of
Temperature
2
**Specific heat
**Specific heat is the amount of heat needed to raise one gram of a substance of one degree Celsius.
**Specific heat of a material is it's ability to store heat.
Temperature
2
Water
• water is an unusual substance in that it must absorb a large amount of heat before its temperature rises by one degree.
• We say that water has a high specific heat.
• Specific Heat is a physical property
2
Lakes and Air Temperature
• Figure 16 – page 174
• A lake is cooler than the air during the day and warmer than the air at night.
Temperature
2
it takes longer for water to warm up or cool down than it does for the air and land around it.
• This is due to water’s high specific heat
Heat on the Move
Temperature
2
• Remember: Heat moves from warm places or objects to cooler ones.
• This transfer can take place in three ways—radiation, conduction, and convection.
Conduction:
mostly between solids and liquids
• It is the transfer of energy by collisions between the atoms.
• Atoms that collide are in contact with each other
2
So, Conduction is heat transfer by direct contact
Conductors
• Are materials that can transfer thermal energy
Temperature
2
• Most metals are good conductors of heat.
Insulators
• Some materials that are poor conductors of heat can be used as thermal insulators, that don’t allow the heat to escape.
Temperature
2
• Clothes, thermos and blankets are poor conductors of heat
• ( that is why you use a blanket to keep warm. The blanket will not let the heat escape)
Convection:
mostly in gases and liquids
• It is the transfer of heat that happens when particles move between areas that differ in temperature.
2
• During convection, the warmer gases or liquids go up and the cooler goes down
Convection in liquids2
In a pot of boiling water, the warmer, less dense water is forced up as the cooler, denser water sinks.
Source of heat
Radiation
• Is the transfer of energy in the form of waves
Temperature
2
• When these waves strike an object, the energy in the waves will be absorbed by the object and the temperature of this object will rise.
• We saw this in our radiation lab when we warmed up soils and water.
More examples of Radiation
2
• Heat is transferred by radiation from the fireplace and you become warmer.
• A microwave oven cooks food by using microwave radiation to transfer energy to the food.
Atoms and molecules
Two atoms of hydrogen and one of oxygen will
form a molecule of water. The atoms will bond
chemically to form the molecule.
1) What is a chemical reaction?
• In a chemical reaction, compounds or molecules are broken down or new compounds are formed.
3
After a ch. reaction, some atoms might not be
combined in molecules, so they will be free to form
some other compounds and molecules
2)Explain how energy and chemical bonds
are related. What type of energy you find in
chemical bonds, kinetic or potential?
Two atoms united by a
chemical bond.
There is energy stored
in the bonds between
atoms.
The energy is called
chemical energy
Different types of Energy
(potential and kinetic)
Potential Energy:
A) Nuclear
B) Elastic
C) Gravitational
D) Chemical
Chem. En. is a type of Potential Energy
Energy in Reactions3
• Energy must be added before the reaction can begin.
• This energy is required to break the chemical bonds so atoms will be free to make new molecules
• This energy can be supplied by electricity, heat, or light
3) Explain what happens to the energy in our muscles.
3
• When you eat, the food provides chemical energy that will remain stored in your body.
• This energy will be used by your cells to perform many different functions
• The muscles in your body transform some of this chemical energy into kinetic energy and heat when they move.
4)What are endothermic and exothermic reactions?
A chemical reaction that absorbs heat energy is called an endothermic reaction.
Exothermic reactions are chemical reactions that release heat energy. Energy can also be released in the form of light.
Chemical Energy
3
5) Explain Photosynthesis and why photosynthesis one of the most important endothermic chemical reactions on Earth?
3
6) What is Rate of Reaction ?
• Rate of reaction is how fast or how slow a chemical reaction happens.
• Chemical reactions can occur at different rates.
3
Ex of fast - fireworks exploding
Ex of slow - rusting
7)What are the two ways you can use to
change the rate (speed) of a chemical
reaction?
• Adding a catalyst or changing the
temperature
• When you raise the temperature you
accelerate a chemical reaction
Catalyst3
• A catalyst is a substance that changes the rate of a chemical reaction without any permanent change to its own structure.
• The catalyst doesn’t participate in the chemical reaction, but accelerates it.
Catalysts
• Enzymes are catalysts in our body and regulate most of the chemical reactions in our body
• important for growth, respiration, digestion….
3
Lab
• Chapter 6 – Energy
• There different types of Energy
• What is the Law of Conservation of
Energy?
• This lab is about Energy Transformations
Lab: Exothermic Reaction
Chemical energy transformed into heat
Procedure
1.Measure the temperature of the peroxide in
the container labeled P.
2.Record the temperature
3.Stir in the yeast. Take the temperature of
the mixture and record.
On a separate sheet of paper put your
name, date and title , and answer:
On a separate sheet of paper put your
name, date and title , and answer:
1) What is the amount of temperature
difference of the water before and after
adding peroxide to yeast?
2) Is this an endothermic or exothermic
reaction ?
3) IMPORTANT: in this experiment you
observed chemical energy being
transformed in heat energy.
Demo: Cool Light
• Production of light from a chemical
reaction
• Chemical Energy being transformed in
light energy
Title: Cool Light
1) What did you observe when the teacher
mixed the two components?
2) The two liquids reacted chemically.
What is the evidence of this chemical
reaction?
3) The two liquids reacted chemically, so
we can say that the chemical energy in
the bonds of the liquids changed into
________ energy.
