KS3 Science Home learning Reactions 2 Name: _____________________________ Class: _____________________________ Teacher: ___________________________ In this topic you will learn about: • Exothermic and Endothermic reactions. • How to represent energy changes in reactions. • How to speed up reactions. Practical skills: • Measuring temperature changes This will prepare you for: • GCSE Chemistry • GCSE Physics Maths in science: • Reading a graph • Calculating differences in temperature and energy
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PowerPoint PresentationName: _____________________________ Class:
_____________________________ Teacher:
___________________________
In this topic you will learn about: • Exothermic and Endothermic
reactions.
• How to represent energy changes in reactions.
• How to speed up reactions.
Practical skills: • Measuring temperature changes
This will prepare you for: • GCSE Chemistry
• GCSE Physics
Contents:
Booklet Expectations:
The booklet is your responsibility to look after and keep
tidy.
You are expected to bring the booklet to every lesson with that
class teacher.
Any corrections / self assessment to be completed in green pen, as
indicated by your class teacher – Or when you see the ‘feedback
& assessment’ logo
Any response to marking and literacy codes to be completed in green
pen.
Any diagrams are to be drawn in pencil, graphs using a pencil and
ruler etc.
All activities are to be completed, including homework, to the best
of your ability, and corrected where needed.
When reading through the notes, you are expected to highlight any
words you do not understand, then write their definitions on the
glossary pages at the back of the booklet.
Lesson 1: Exothermic reactions Lesson 2: Endothermic reactions
Lesson 3: Investigating endothermic reactions Lesson 4: Catalysts
Lesson 5: Exploring combustion Lesson 6: Exploring the use of fuels
Lesson 7: Understanding thermal decomposition Lesson 8: Explaining
changes Lesson 9: Revision Lesson 10: Test Lesson 11: Green for
Growth
Week commencing 8th Feb – 1st March 4 lesson per week
Key term Definition
Lesson 1: Exothermic Reactions
Lesson 1: Exothermic Reactions
In and On: Look at the images on the board. Are the following
physical or chemical changes?
1. Ice melting
3. Burning magnesium
Challenge: What is the difference between a physical and chemical
change?
Learning Objectives • Describe examples of exothermic reactions •
Explain the energy changes taking place during an exothermic
reaction
Challenge: An example of an exothermic reaction is….
Energy changes occur in all ___________ ____________. In exothermic
reactions, energy is ________ _____ , usually in the form of
______. This means that the temperature of the surroundings
__________.
Record your observations to identify the exothermic reaction
Explain, using ideas about particles and atoms, why burning
magnesium is an exothermic reaction.
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Citric acid and baking soda Magnesium ribbon and Hydrochloric
acid
Temperature at start (oC) 23 22
Temperature at end (oC) 10 42
Conclusion:
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Citric Acid and Baking soda 1. Add 2cm depth of citric acid to
a
test tube 2. Record temperature 3. Add 1 spatula scoop of
baking
soda 4. Record temperature
Magnesium ribbon and Hydrochloric acid 1. Add 2cm depth of
Hydrochloric
acid to a test tube. 2. Record temperature 3. Add a few pieces od
magnesium
ribbon 4. Record temperature
Lesson 2 : Endothermic reactions
Endothermic reactions Energy from the surroundings is transferred
to the reacting chemicals, causing the temperature of the
surroundings to decrease. Examples include: •Thermal decomposition
•The reaction between citric acid and sodium hydrogen carbonate
(sodium bicarbonate).
Lesson 2 : Endothermic reactions
In and On: Using only addition, how can you add eight 8's to get
the number 1,000?
Learning Outcomes: • Describe examples of endothermic reactions •
Explain the energy changes taking place during an
endothermic reaction
What is the difference between endothermic and exothermic
reactions? _______________________________________________________
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Practical 1: 1. Fill a test tube 1/3 with
Copper sulfate 2. Record the temperature 3. Add a 2cm length
of
magnesium ribbon 4. After 1 minute, record the
temperature. Results: 5 degree temperature
increase
Practical 2: 1. Fill test tube 1/3 water 2. Add 1 spatula of
Sodium
Bicarb 3. Record the temperature 4. Add 1 spatula of Citric acid 5.
After 1 minute, record the
temperature. Result: 7 degree temperature decreasePractical 1
This reaction was ____________. I know this because…
Practical 2 This reaction was ____________. I know this
because…
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Reaction Start Temp (oC) End Temp (oC) Temp Change (oC) Exo or
Endo
A 22.0 33.4
B 18.6 41.7
C 24.3 19.5
D 6.1 21.7
E 22.0 -3.6
F -12.2 2.3
Endothermic reactions In an endothermic reaction, more energy is
_____________. Endothermic means to take in _________. This means
that in an endothermic reaction, the temperature _____________. The
most important endothermic reaction for life is
________________.
1. Which type of reaction gives out energy to the
surroundings?
2. Thermal decomposition is an example of …
3. Combustion is an example of…
4. Which type of reaction causes the temp of the surroundings to
decrease?
5. An Ice pack is an example of…
Endothermic or Exothermic?
How can you tell this reaction is endothermic?
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Lesson 3: Investigating endothermic Reactions In and On: Is this
reaction endothermic or exothermic?
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Challenge: How do you know?_______________________________
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1. Measure out 10 cm3 of water using a measuring cylinder. Record
the starting temperature of the water in your results table
2. Collect a polystyrene cup with a pre weighed amount of potassium
chloride in it. Record the mass to the appropriate number of
decimal places in the table.
3. Add the water to your cup. Record the lowest temperature shown
on your thermometer and record this answer to the appropriate
number of decimal places.
4. Calculate the change in temperature.
Method:
Start temperature (oC)
End temperature (oC)
• Remove any anomalous results
• Ensure you have labelled each axis and state the unit
• Ensure gaps are uniform ie. Every square is equal to 2 degrees
Celsius
• Draw a line of best (either with a ruler or a curve – do NOT join
the points)
Conclusion:
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Challenge: Why did you use a polystyrene cup rather than a beaker?
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How could you improve the experiment to make your results more
reliable?
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Additional notes: _________________________________________________
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Remember – Particles need to collide with enough energy (activation
energy) to react. A catalyst provides an alternative reaction
pathway with a lower activation energy, so there are more
successful collisions.
Lesson 4: Catalysts In and On: Which road would you choose and why?
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Road 1
Road 2
1. What are the 4 factors affecting the rate of reaction?
2. What is the activation energy?
3. What does the rate of a reaction depend on? 1. 2.
4. Why does the rate of reaction increase with increased
temperature?
5. Why are catalysts not included in reaction equations?
6. How do catalysts speed up the rate of reaction?
7. Give 2 examples of catalysts
Additional notes:
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Learning Objectives:
• To describe what a catalyst is • Explain how catalysts work
Which graph shows a reaction with a catalyst? Explain your answer.
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U si
n g
th e
in fo
rm at
io n
s h
ee ts
Reactions 2 Catalysts
Nitrogen + Hydrogen → Ammonia
N2 (g) + 3 H2 (g) → 2 NH3 (g)
An iron catalyst is used to speed up the rate of this
reaction.
Making Margarine
This type of reaction is known as hydrogenation.
Example: Ethene + Hydrogen → Ethane
A nickel catalyst is used to speed up the rate of this
reaction.
Reactions 2 Catalysts
Reactions 2 Catalysts
A three step reaction. The catalyst is needed in step 2.
Step 1: Sulfur + Oxygen → Sulfur dioxide Step 2: Sulfur Dioxide +
Oxygen → Sulfur Trioxide Step 3: Water + Sulfur Trioxide → Sulfuric
Acid
A Vanadium Oxide catalyst is used to speed up the rate of this
reaction.
Catalytic Converters in Cars They convert harmful emissions into
less harmful substances.
Carbon monoxide + Oxygen → Carbon dioxide 2 CO (g) + O2 (g) → 2 CO2
(g)
Carbon monoxide + Nitrogen monoxide → Carbon dioxide + Nitrogen 2
CO (g) + 2 NO (g) → 2CO2 (g) + N2 (g)
Hydrocarbons + Nitrogen monoxide → Carbon dioxide + Nitrogen +
Water
Rhodium, Palladium and Platinum can be used as a surface for the
catalytic converter.
Reactions 2 Catalysts
Challenge: Write this as a symbol equation:
Lesson 5: Combustion
In and On: match the reaction to its definition
Extension: how are hand warmers an example of an exothermic
reaction?
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Physical reaction
Physical properties of a substance changes but no new substances
are made
Chemical reaction
Exothermic reaction
Endothermic reaction
One or more substances are changed into others by rearranging their
atoms
Learning Objectives: • Summarise combustion using an equation •
Make observations during chemical reactions • Write word equations
to represent chemical equations
Methane + Oxygen → Carbon dioxide + Water
When a fuel burns, chemical energy is transferred into heat
___________. Wood, coal, petrol and gas are all examples of
___________. Burning is a _________ reaction. The scientific name
for burning is _______________.
When a fuel burns, it reacts with ____________ in the air to form
carbon dioxide and ______________. The reaction also gives out
______________ energy.
CH4 + O2 → CO2 + H2O
Can you light a candle on the moon? Explain your answer.
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Label the reactants and products for the following reaction:
Write this as a symbol equation:
CH4 + O2 → CO2 + H2 O +
What is the difference between complete and incomplete combustion?
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Describe why burning is a chemical reaction
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Explain why a fire will burn more brightly is you fan the flames
with air
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Describe the problems associated with the production of carbon
dioxide
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Challenge Explain why combustion is also known as an oxidation
reaction
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Additional notes:
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Lesson 8: Explaining changes
Lesson 8: Explaining changes
In & On: What would be the mass of the salt solution? Explain
your answer.
Law of conservation of mass
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What is physical change?
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Learning Objectives:
• Observe and explain mass changes for chemical and physical
processes • Use particle diagrams to explain chemical
processes
Mass of water: 250g Mass of salt = 5g
If 6g of calcium reacts with 2g of oxygen, what mass of calcium
oxide will form?
If 12g of calcium oxide forms from 9g of calcium, what mass of
oxygen has reacted?
Examples: Calcium + Oxygen → Calcium oxide
Magnesium and Magnesium Oxide are both solids at room temperature.
Oxygen is a gas. Predict – what would appear to happen to mass when
they react?
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Burning Magnesium
Describe and Explain what appears to happen to mass when magnesium
and oxygen react.
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Challenge: Describe and Explain what appears to happen to mass
during the thermal decomposition of copper carbonate.
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Total mass of reactants = Total mass of products
If one of the reactants is a gas, mass can appear to
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If one of the products is a gas, mass can appear to
________________
10.00g 50.00g
5.00g 9.00g
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4 K (s) + O2 (g)→ 2 K2O (s)
Additional notes
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End of Topic Summary Questions:
•
•
Write out a word equation for the reaction
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C3H8 + O2 → CO2 + H2O
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Revision The next 2 pages are left blank for you to use for
revision in preparation for the end of topic test. Your teacher may
ask you to complete a specific revision activity or ask you to
revise independently. Suggested activities include: Mind maps,
practice questions from the text book, flash cards, memorising key
words and concepts.
Student book part 2 pages 102-121