Thursday, October 23rd, 2014
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Homework
◦ Define the following types of reactions
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Synthesis
Decomposition
Single Replacement
Double Replacement
Due Tuesday:
VSVS on Monday
◦ Complete questions 4 and 6 from page 160 in
textbook (reading from page 154-160)
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Do Now
Balance the following chemical equations
__Na + __HCl  __H2 + __ NaCl
__C2H6 + __ O2  __CO2 + __H2O
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SWBAT identify endothermic and exothermic
reactions by looking at a graph.
Essential Question:
How can you tell the difference between
endothermic and exothermic reactions?
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Some chemical reactions produce heat
◦ what are some examples?
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Some chemical reactions absorb heat
◦ What are some examples?
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Endothermic
◦ A reaction that absorbs heat
 “more energy is needed to break the bonds than is given off
to form new bonds.”
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Exothermic
◦ A reaction that releases heat
 “after an exothermic reaction the temperature of the
surroundings rises because energy is releases.”
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Activation energy
◦ the amount of energy (heat) needed to start a chemical
reaction.
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ΔH or
ΔT
◦ Change in heat or temperature
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Write down a way that you can remember the
difference between the two.
EXothermic = EXplosion = produces heat
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Title: Endothermic and Exothermic reactions
Date: 10/24/2014
Unit: Chemical Changes
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Copy graphs
ΔT
Reaction A
ΔT
Reaction B
A. What are the chemicals in an ice pack and
what type of reaction is it?
B. When the narrator starts talking about
energetics, what are molecules always doing
and how are temperature and movement
related?
C. How are the attractive forces between
molecules related to energy and
temperature?
D. Why does your cold pack get cold?

What is happening inside of our cold pack?
◦ What are the steps/sequence
◦ 2 minutes to write your answer
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What is happening inside of our hand
warmer?
◦ Hand Warmers
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How can you tell the difference between
endothermic and exothermic reactions?
A
1.
2.
Label the following
graphs as
endothermic or
exothermic
reactions.
Write one sentence
explaining how you
know each one is
endothermic or
exothermic.
B
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We learned about
◦ Physical properties and changes
◦ Chemical properties and changes
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Reading chemical reactions
◦ Products and reactants
◦ Coefficients and subscripts
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Balancing chemical equations
Common outcome of ALL chemical reactions
VSVS on Monday
HW due Tuesday