Purpose
•
The purpose of second part of this unit is to
investigate and understand energy, energy
transfers/storages, and energy involved in chemical
reactions.
•
We are going to do this through modeling of a
phenomena— The Hindenburg Disaster 1937
The Hindenburg Story
https://www.youtube.com/watch?v=CgWHbpMVQ1U
Hindenburg Airship
Before
•
During
After
HoWhy did the Hindenburg burn in 37 seconds?
Complete your initial thoughts
Your Initial Group Models
Before
•
During
After
How did the Hindenburg burn in 37 seconds?
End of Day 1
Big Idea Investigate and understand energy, energy
transfers/storages, and energy involved. in chemical
reactions.
Question: How did the Hindenburg
burn in 37 seconds?
Today:
Exploring Energy
What is Energy?
•
Energy is the stuff that makes stuff (particles) do stuff.
•
Energy is required to make things change
•
Energy is the ability to do work. (Phys. Science)
•
Work is the application of a force to move an object in the
direction of the direction of the force.
•
A force is an influence that can cause an object to move
or stop an object that is already moving.
•
Motion is a change in distance over time.
1 Kind of Energy
1. Energy is energy— There is only one kind of energy
called energy.
2. Things you can do to energy: store or transfer
Accounts- Where can
“money” be.
Spend Now
Have to do some work to spend
1 Kind of Energy
3. Energy is stored in different accounts:
Ways Energy is Stored
Kinetic Energy
Potential Energy
•
Electrical Energy
•
Chemical Energy
•
Thermal Energy
•
Phase Energy
•
Sound Energy
•
Mechanical Energy
•
Radiant Energy
•
Nuclear Energy
•
Movement Energy
•
Gravitational Energy
Unit 3- Chemical
Energy Notes
The
st
1
Law of Thermodynamics
•
Key Concept 1: The first law of thermodynamics
states that energy can neither be created nor
destroyed. Energy is conserved.
•
Law of Conservation of Energy
KC 2: Movement Energy (KE)
When objects or
materials flow or move
from one place to
another they produce
energy, such as water
flowing through a dam.
KC 3: Electrical Energy (KE)
•
The energy associated
with the movement of
electrons.
•
Electrical charges
moving through a wire is
called electricity.
•
Lightning is another
example
KC 4: Thermal Energy (KE)
•
The energy that results
from the movement of
atoms and molecules and
is related to their
temperature.
•
The faster particles move,
the greater amount of
energy and the higher the
temperature.
KC 5: Sound Energy (KE)
•
Produced by the periodic
movement of matter in a
medium.
•
Sound can travel through
air, solids, and liquids,
but not through a
vacuum, because there
is no matter there.
KC 6 : Radiant Energy (KE)
•
Electromagnetic waves are a result of the vibration of
charged particles such as electrons.
•
Microwave ovens use radiant energy to heat food by
causing the water molecules to vibrate.
KC 7 : Mechanical Energy (PE)
•
Energy is stored in the
mechanical device by the
application of a force, such as
when we wind the clock or
pull the bow back.
•
Examples include a clock that
is powered by a wound-up
spring, or a bow and arrow.
KC 8: Nuclear Energy (PE)
•
When the nucleus of an
atom splits or is fused to
another nucleus, energy
can be released.
•
It is the type of energy that
powers our sun and is
found in nuclear power
plants.
KC 9: Gravitational Energy (PE)
•
•
This is the energy associated with an
object’s position in a gravitational field.
•
A ball resting at the top of a ramp has higher
potential energy than when it has rolled to the
bottom.
•
Water behind a dam has higher potential
energy than when it has flowed to the river
below.
In each case the potential energy is
due to relative position in the
gravitational field.
KC 10: Chemical Energy (PE)
•
Is energy stored in a
substance chemical bonds.
•
It takes energy to break
bonds and energy is released
when new bonds form.
•
Chemical bonds hold atoms
together.
KC 11: Phase Energy (PE)
•
Is energy stored in a
substance based on the
arrangement of particles.
Learning Check
•
What type of energy is shown here?
Learning Check
•
What type of energy is shown here?
Learning Check
•
What type of energy is shown here?
Energy Flow Diagrams
•
Key Concept 12: Energy Flow Diagrams illustrate
how energy is stored or transferred in a system or
object.
•
There is often branching where one form of energy
can be transformed into two or more other forms at
the same time.
•
Example: Cell Phone
thermal
Learning Check
Key Concept 13:
•
What type of energy is shown here?
•
Energy Flow Diagram
Exploring Energy Lab
•
Goal: Determine the kinds of energy involved with the
operation of common toys and draw energy flow
diagram to illustrate how energy is transferred.
Exploring Energy Lab
Part 1: Gathering Evidence (1 pts each)
• Write a description of what you observe.
Part 2: Analyzing Evidence (1 pts each)
• Use the list of “types” of energy involved in the operation of each toy (Key
Concepts 2 -11).
Part 3: Interpreting Evidence (3 pts each)
• Draw an energy flow diagram to represent the energy storages/transfers
(Key Concept 12 &13).
Part 4: Conclusion
• Answer 2 of the 6 conclusion questions (Your choice!)
• Turn in to the bin.
End of Day 2
How do these hand
warmers work?
Now we get to mess with
Chemical Energy
What are our energy accounts?
Eth Account- Thermal Energy (KC 4)- is the energy stored
by moving particles.
Deposit- Move faster
Withdraw- Move slower
Eph Account- Phase Energy (KC 11)- is the energy stored in
the system due to the arrangement of particles that exert
attractions on one another.
Deposit- Break up the arrangement (decrease intermolecular forces)
Withdrawal- Allow arrangement to reform (increase intermolecular forces)
What are our energy accounts?
Key Concept 14: Ech- Chemical Energy (KC 10 )- is the
energy due to attractions of atoms within molecules.
Deposit- During a chemical reaction, the energy stored in the reactants
bonds is less than the products bonds.
Withdrawal- During a chemical reaction, the energy stored in the reactants
bonds is greater than the products bonds.
LOL’s with Chemical NRG
•
In our quick hand warmer demo, the oxygen in the
air reacted with the iron powder to create rust and
heat. Draw an energy bar chart to represent the
energy storage and transfer.
LOL’s with Chemical NRG
Key Concept 15: Hand warmer demo
LOL’s with Chemical NRG
•
Key Concept 16: In LOLOL diagrams, the amount of
energy between reactants and products in a
chemical reaction must be equal within the system
(1st law of Thermodynamics cannot be broken).
Chemical Energy Demos
- Energy Flow Diagrams
-LOL
End of Day 3
Bellwork
•
Looking at Demo 2 and 3 from yesterday and your
prior knowledge about the vocabulary exothermic
vs. endothermic from biology; copy and complete
the following 2 sentences.
•
In an endothermic reaction energy is released to/
absorbed from the surroundings and demo # 2/3
was an example of an endothermic reaction.
•
In an exothermic reaction energy is released to/
absorbed from to the surroundings and demo # 2/3
was an example of an exothermic reaction.
Endothermic Reactions
•
Key Concept 17: Endothermic reactions are
chemical reactions where the system absorbs
energy from its surroundings in the form of heat.
Ech
for
Reactants
Ech
for
Products
Exothermic Reactions
•
Key Concept 18: Exothermic reactions are chemical
reactions that release energy to the surroundings in
the form of light or heat.
Ech
for
Reactants
Ech
for
Products
End of Day 4
Bellwork
•
How do you think instant hot and cold packs work?
(5 Sentences) Keep in mind chemical reactions and
energy.
Hot or Cold Pack???
•
Experiment A (odd numbered lab stations):
– You will be mixing spoon full of sodium bicarbonate
(NaHCO3) that is in beaker A, with 2 squirts of water in a
sandwich bag.
• Experiment B (even numbered lab stations):
– You will be mixing spoon full of calcium chloride (CaCl2)
that is in beaker B, with 2 squirts of water in a sandwich
bag.
Quick Lab Conclusion Questions
•
Key Concept 19 : Complete the following sentence
starters for both experiments
1. Experiment ___ (A/B) is similar to ___ (hot/cold pack).
2. The heat energy is _____ (given off/taken in).
3. The temperature _____ (falls/rises).
4. Reaction ___ (A/B) is _____ (endothermic/exothermic)
Repeat for other experiment
Activation Energy
•
Key Concept 20: Activation energy is the minimum
amount of energy required to initiate a chemical
reaction.
•
https://www.youtube.com/watch?v=VbIaK6PLrRM
•
Is any reaction spontaneous?
Chemical Energy
•
Chemists are interested in changes in energy during
reactions.
•
Key Concept 21: Enthalpy is a measure of the total energy in
chemical bonds.
•
Enthalpy is also known as the heat of reaction, or H.
•
The change in enthalpy during a reaction symbolized as
ΔHrxn.
ΔHrxn = Hfinal – Hinitial
ΔHrxn = Hproducts – Hreactants
KC 22: (Draw the graph)
Exothermic Reaction: A chemical reaction that
releases energy in the form of light or heat.
Activation Energy
Energy of reactants
∆ H is known as the
“heat of
the reaction”
Reactants
Energy of products
•Energy
•
-∆H Exothermic
Products
•Reaction Progress
KC 23: (Draw the graph)
Endothermic Reactions: Chemical reactions that
absorb energy in the form of heat
Energy of reactants
Energy of products
Activation
Energy
Energy
•
Products
+∆H Endothermic
Reactants
Reaction progress
End of Day 5
Bellwork
•
Draw this energy
diagram and label the
reactants, products,
heat of the reaction
(enthalpy), activation
energy, and whether
the reactions is
endothermic or
exothermic.
(Hint: Look at your notes KC 22 and 23)
Rm. 169429
Learning Check
(T) Endo or (F) Exo… Which is it?
Learning Check
•
(T) Endo or (F) Exo… Which is it?
• What is the heat of reaction?
• What is the activation energy?
• Is the reaction endothermic or exothermic?
• What is the heat of reaction?
• What is the activation energy?
• Is the reaction endothermic or exothermic?
1) The heat of reaction for this reaction is:
A) +160 kJ
B) +280 kJ
C) -160 kJ
D) -280 kJ
2) The activation energy for this reaction is:
A) 20 kJ
B) 60 kJ
C) 160 kJ
D) 260 kJ
3) The following describes this reaction:
A) endothermic, +ΔH
B) endothermic, -ΔH
C) exothermic, +ΔH
D) exothermic, -ΔH
•
Move into desk partners and complete problems C
10-15
•
On your whiteboard write the concept that was the
hardest or you still don’t understand, then bring your
board up front.
Closure (Stamp)
(Sketch in explain everything
with your shoulder partner)
•
Sketch a potential energy curve that is
represented by the following values of ΔH and
activation energy. You may make up appropriate
values for the y-axis (potential energy).
ΔH = -50 kJ and Activation Energy = 20 kJ
•
Is this an endothermic or exothermic reaction?
End of Day 6
Hoffman’s Apparatus
•
https://www.youtube.com/watch?v=OTEX38bQ-2w
Summary
Endothermic
•
summary of differences
Exothermic
What’s the balanced reaction?
•
Oxygen gas (in the air) reacted with hydrogen gas
(in the blimp) to form water.
•
Oxygen- Red Paper Clip
•
Hydrogen- Sliver Paper Clips
•
On the whiteboard- balance chemical equation and
a particle diagram of the reaction.
•
Do not forget the Law of Conservation of Mass
KC 24: What’s the
balanced reaction?
End of Day 6
https://www.youtube.com/watch?v=CgWHbpMVQ1U
Hindenburg
•
Cigarette?
•
Sabotage?
•
Thunderstorm or Spark?
•
Outside Material covered in “Rocket-Fuel”?
http://preview.discovery.com/tv-shows/mythbusters/videos/hindenburg-minimyth/
Your Final Group Models
Before
•
During
After
How did the Hindenburg burn in 37 seconds?