Boyd, P.1
200312436
Amanda Boyd-Learning Cycle
1. Introduction:
a) Objectives for the overall learning cycle.
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Experience a variety of chemical reactions.
To understand the difference between acids and bases
To get students interested in science and learn lab safety
b) Why you think this is a suitable topic?
This is a suitable topic because there is a chemical reaction happen in our everyday life and we could not
live without chemical reaction. For example baking cookies or pizza would have some type of chemical
reaction involved. As well it is a unit in the Saskatchewan Science 10 Curriculum and it is used as
scaffolding for Chemistry 30, if students want to take it. Plus when students take science they expect
some to have some hands on lab experiments. Chemical reactions are an easy topic to allow students to
do lab work rather than just taking notes and remembering facts. Before students are allowed to
perform these labs they need to know some lab safety and lab etiquette.
c) Curriculum fit / curriculum objectives
Science 10 Chemical Reactions
SCI10-CR1 Experience a variety of chemical reactions, including the role of energy changes.
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g. Investigate potential benefits and consequences of endothermic and exothermic chemical
reactions.
a. Create a representation about the prevalence of chemistry in our lives.
f. Differentiate between reactants and products in chemical reactions.
e. Explain why it can be difficult to classify changes as physical or chemical, including reference
to the reversibility of the reaction.
SCI10-CR2 Name and write formulas for common ionic and molecular chemical compounds, including
acids and bases.
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i. Classify substances as acids, bases, or salts, based on observable characteristics, name, and
chemical formula
Foundation 3 of Science: Scientific and Technological Skills and Processes
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Preforming and recording data
Analyzing and Interpreting
Communication and Teamwork
Boyd, P.2
200312436
d) How you will judge the overall success of the learning cycle
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An understanding of concepts and growth of knowledge containing Chemical Reactions
Students are able to communicate their ideas and work in groups
Students are interested in the nature of science
e) Best estimate of an ideal time
This learning cycle should take 5 classes therefore 5 hours.
Engagement Activity: Elephant Toothpaste
-Teacher lead activity
Materials:
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Tall graduated cylinder (at least 500 ml)
50mL graduated cylinder
Breaker
Food Colouring
Dawn Dish Soap
120 mL of 6% Hydrogen Peroxide (H2O2)
1 Tablespoon of dry yeast. (one tablespoon of dry yeast is 15 mL or 15 g)
45 mL Water (H2O)
Safety Glasses
Lab Coat
Gloves
Safety:
o
o
A lab coat, gloves, and safety glasses are a must! As a teacher it is important to explain why you
have to wear these items of clothing. You wear the lab coat because you do not want to ruin
your clothes or some labs the chemicals can burn through your clothes which means it can burn
though your skin. Hydrogen peroxide is an oxidant and can irritate skin and eyes, so the glasses
and gloves are also needed.
Also stress that you never eat something that in a lab unless told otherwise. For you cannot
always tell if there is chemical residue in the lab equipment. Since it is called elephant
toothpaste a student might ask if you can use it to clean your teeth and it is not.
Procedure:
1. Measure out 120 mL of 6% Hydrogen Peroxide in a tall graduated cylinder.
2. Add 8 drops of your favorite food coloring into the bottle.
3. Add about mL of liquid dish soap into graduated cylinder and swirl the graduated cylinder to mix
the solutions.
Boyd, P.3
200312436
4.
In a separate beaker add 45mL of warm water and the 15mL yeast (you can use the graduated
cylinder to measure) together and mix for about 30 seconds, until the yeast has dissolved in the
water.
5. Pour the yeast water mixture into the Hydrogen Peroxide solution. You may want to step back.
6. Watch what happens!
What Happens:
The Hydrogen peroxide mixes with the yeast solution allows a surprising large amount of bubbles to
form creating foam.
Why it Happens:
The reason it is called elephant toothpaste is because a huge amount of foam is formed. The
yeast was a catalyst speeding the reaction rate. This is a chemical reaction Remember the catalyst
speeds up the reaction, but remains unchanged through the reaction. This is why so many bubbles
containing dioxide spontaneously formed. The chemical equation would be:
2H2O2(aq)  2H2O(g) + O2(g)
The experiment resulted in an Exothermic Reaction. An exothermic reaction is a reaction that releases
energy thought giving off heat to the environment. As well this is a decomposition reaction for you start
off with one reactant and results in two products.
AB  A + B
Questions:
1.
What type of a reaction occurs?
A. A exothermic reaction
B. A decomposition reaction
2.
What was the chemical equation of the reaction?
A. a.
3.
Why is it called elephant tooth paste?
A. A larger amount of foam is formed at once.
4.
Are these physical or chemical changes?
A. Chemical changes
5.
What were some the observations you noticed?
Boyd, P.4
200312436
A. Lots of bubbles were formed!
B. It was large
Goals / Objectives:
-An understanding of what a chemical reaction compiles of.
-Sparked interest in chemical reactions.
-What endothermic reactions are.
Source
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http://www.sciencebob.com/experiments/toothpaste.php
With additional help from http://chemistry.about.com/od/chemistryglossary/g/DecompositionReaction-Definition.htm
Exploration Activity #1: Quick Freeze
-student centered activity
Materials:
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10g barium hydroxide
5g ammonium thiocyanate (or ammonium chloride)
automatic balance
50mL beaker.
Glass stir rod.
Thermometer.
Small pieces of wood or cardboard. (need to be bit bigger than the bottom of the 4500mL
beaker
Glass Pasteur pipettes with latex bulbs
1 piece of Litmus paper
Safety:
-lab coat and googles are needed since ammonium is being used.
-If you get any of the mixture on your hands wash your hands right away with water
Procedure:
Boyd, P.5
200312436
1. Using the Glass Pasteur pipettes with latex bulbs collect some water from the tab. Drop 5 drops
of water on a small piece of wood (or cardboard), and place the beaker on top.
2. Measure out 10g of barium hydroxide using and automatic balance in the beaker.
3. Measure out 5g of ammonium thiocyanate using and automatic balance in the beaker
4. Stir mixture for 1 min.
5. Take a piece of litmus paper and using the glass Pasteur pipette add 1 drop of water to dampen
it. Now hold the litmus paper over the beaker. Observe what color it changed.
6. Pick up the beaker from the top.
7. Record the temperature of the mixture
What Happened:
When the two solids are mixed together a liquid is formed and freeze into a slush. As well the beaker
shall freeze to the wood. The beaker should be noticeably cold
Why it Happened:
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This is an endothermic reaction for there was more energy needed to break bonds then the
energy released therefore energy was absorbed from the surroundings making it cold. The
reaction:
Ba(OH)2(s) + 2 NH4SCN (s)  Ba(SCN)2 (s) + 2H2O (l) + 2 NH3 (g)
The temperature is reduced to -20°C to -30°C
Questions:
1.
What type of a reaction occurs? How can you tell?
A.A Endothermic reaction, and it was really cold and you could smell ammonia
2.
Where could you see an endothermic reaction in your daily life?
A. melting ice cubes
B. cooking an egg
3.
What was the chemical equation of the reaction?
A.
4.
What is an Endothermic reaction?
A.A cold reaction
B.A reaction where energy is absorbed from the surrounding so the reaction can occur.
5.
What Temperature was observed?
Boyd, P.6
200312436
A. -20°C to -30°C
6.
Did the litmus paper indicate a base or acid?
A. Base
7.
What happened to mixture that indicated a chemical change?
A. A change in temperature, it got cold.
Goals / Objectives
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What a endothermic reaction is
Teamwork for this lab would be done in groups 2 to 3
A connection between science and their daily lives. (when will I ever need this?)
Starting a bit of inquiry to acids and bases (I would probably teach acids and bases after this
subject)
Source - http://www.sciencecompany.com/Fast-Freeze-Experiment.-An-Endothermic-Reaction..aspx
With addition help from
http://chemistry.about.com/od/chemistrydemonstrations/a/endothermicrxn.htm
Exploration Activity #2 Exothermic and Endothermic Reactions
-student centered activity
Materials:
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Safety:
Eye protection
Four test-tubes or four expanded polystyrene cups with lids to act as calorimeters
Spatula
Teat pipette or small measuring cylinder
Thermometer
Access to a balance.
Anhydrous copper(II) sulfate (Harmful)
Citric acid crystals (2-hydroxy-1,2,3-propane tricarboxylic acid)
Sodium hydrogen carbonate
Copper(II) sulfate solution 0.5 mol
Zinc powder (Flammable).
Boyd, P.7
200312436
-Zinc is flammable so be careful
-Anhydrous copper(II) sulfate is poisonous so do not inhale and wash hands/skin if it makes contact
-Since these chemicals are being used googles and lab coats are a must
Procedure:
1. Copy this table outline before starting the experiment
2. This experiment is to be done in groups of 3 to 4.
Experiment 1
1. Put 2 mL of water in a test-tube.
2. Record the temperature of the water before reaction.
3. Add a spatula measure of anhydrous (white) copper (II) sulfate. (the measure is about .5mL to 1mL or
copper(II) sulfate.
4. Carefully stir, then using the thermometer, and record the temperature now.
Experiment 2
Boyd, P.8
200312436
1. In a dry test-tube mix one spatula measure (approx. 1mL) of citric acid.
2. Clean the spatula and then add one spatula (approx. 1mL) measure of sodium hydrogen
carbonate.
3. Put 2 mL of water in another test tube.
4. Record the temperature of the water.
5. Add the mixture to the water.
6. Watch what happens and take the temperature of the solution.
Experiment 3
1. Add 5 mL of copper(II) sulfate solution in a test-tube.
2. Record the temperature.
3. Add a spatula measure (approx. 1 mL) of powdered zinc.
4. Record the new temperature
What happened
Experiment one
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It is a Copper(II) sulfate(white) plus water(clear) will turn blue and is gets warmer.
Experiment two
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Sodium hydrogen carbonate(white) + citric acid (clear), lots of bubbles form and the end it is a
cloudy white solution. It becomes colder and colder as the reaction goes on.
Experiment three
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CuSO4 was a blue liquid and Zn(s) is a grey color. Once you mix the two by stirring the mixture
forms bubbles and in the end the liquid is a white color and the solid is now more of a brown
color.
Why it happened
Experiment one
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Anhydrous means to be without water. So it is really just copper (II) sulfate with addition of
water. This is an exothermic reaction since energy is released to the environment.
CuSO4(s) +H2O  CuSO4•H2O
The • means they are attached to the formula, and sometimes is easy to break off. Like this in
reaction it is revisable meaning you can reform the reactants from the produces. This is also a
displacement reaction.
Experiment two
Boyd, P.9
200312436
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This is endothermic reaction, and as result gets colder as the reaction occurs. The bubbles form
because CO2 gas is formed. Since so much energy is needed break the Sodium hydrogen
carbonate bonds it requires energy from the environment.
Sodium hydrogen carbonate + citric acid → sodium citrate + water + carbon dioxide
NaHCO3(aq) + H+(aq) → Na+(aq) + H2O(l) + CO2(g)
Experiment three
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CuSO4 was a blue liquid because of the cupper and Zn(s) is a grey color. Once you mix the two
by stirring the mixture forms bubbles due to the chemical reaction happen. The end the liquid is
a white color and the solid is now more of a brown color showing the Copper and Zinc had
switched places causing a displacement reaction. This is an exothermic for the temperature
increases.
CuSO4(aq) + Zn(s) → ZnSO4(aq) + Cu(s)
Questions:
1. Which reactions are exothermic and which are endothermic?
A. Both experiments 1 and 3 are exothermic, experiment 2 is endothermic
2. How could you tell you had an endothermic or exothermic reaction?
A. The change in temperature from the before and after reaction reading
3. If you were making a cold pack, which substances would you use?
A. Citric acid and sodium hydrogen carbonate, experiment 2.
4. Now if you making a hot pack, which experiment(s) would you use? Why?
A. Experiment 1 or 3 because they are exothermic and give off heat.
5. What do you think are some signs of a chemical change?
A. A change in Temperature
B. Bubbles forming
C. Color change
Goals / Objectives:
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Further explanations of endothermic and exothermic reactions are.
Able to collect and interrupt data
A connection between science and their daily lives. (when will I ever need this?)
Lab safety
Source
-http://www.rsc.org/learn-chemistry/resource/res00000468/heats-of-reaction-exothermic-orendothermic-reactions?cmpid=CMP00000538
Boyd, P.10
200312436
Explain Activity
A class discussion with the following questions, I would write their words instead of mine. This is just
roughly what I expect them to say. As I would be doing this I would be using control questions, by adding
a student’s name to the beginning or end of the questions.
1. What is a chemical reaction?
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A chemical reaction when a new substance is formed and energy is absorbed or released into
the environment.
2. How can you tell a Chemical change has occurred? (Name 4 ways)
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Change in temperature
Change in color
Gas is formed
Change in smell
3. Where can you see everyday chemical reactions?
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Baking
cooking
Your own body
4. In which activity did we see a change in temperature?
- In all the activities.
5. In which activity did we see change in color? What color change occurred?
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Elephant toothpaste
Experiment three CuSO4(aq) + Zn(s) → ZnSO4(aq) + Cu(s) blue  white
Experiment one
white/clear blue
6. What is an endothermic reaction?
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An endothermic reaction absorbs energy/heat from the environment.
7. What are few examples of endothermic reactions we observed in this class?
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Quick Freeze experiment
Experiment two Sodium hydrogen carbonate + citric acid
8. What is an exothermic reaction?
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A endothermic reaction releases energy/heat from the environment
9. What are few examples of endothermic reactions we observed in this class?
Boyd, P.11
200312436
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Experiment 1
Experiment 3
10. Using your knowledge of endothermic and exothermic reactions. Which type of reaction do you
think the elephant toothpaste is and why?
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It is an exothermic reaction because it released a lot of energy by forming so many bubbles.
11. What endothermic reactions would you see outside this classroom?
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melting ice
mixing sugar into coffee
baking cookies
Ice packs
12. What endothermic reactions would you see outside this classroom?
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Heat packs
Making ice
Car rusting
Lighter/ candle flame
Background Information that students need to know from the discussion
1. What is a chemical reaction?
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A chemical reaction when a new substance is formed and energy is absorbed or released into
the environment.
2. How can you tell a Chemical change has occurred? (Name 4 ways)
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Change in temperature
Change in color
Gas is formed
Change in smell
6. What is an endothermic reaction?
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An endothermic reaction that absorbs energy/heat from the environment.
8. What is an exothermic reaction?
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An endothermic reaction that releases energy/heat from the environment.
As well they should know the chemical reactions happen in their daily lives and not just in the science
classroom.
Boyd, P.12
200312436
Extend Activity Reaction in a Bag (NaHCO3/HC2H3O2 and NaHCO3/CaCl2)
Materials:
1. Baking Soda
2. CaCl2
3. Vinegar
4. Phenol red
5. 2 large Ziploc freezer baggies
6. Two 150 mL Beakers
7. 50 mL Graduated cylinder
8. 20mL graduated cylinder
Safety:
-Make sure the students are wearing lab coats and glasses. The materials may be common household
products but it is always better to be safe than sorry and it is always a way to make sure they are
conditioned to practice lab safety
Procedure:
Bag #1:
1.
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5.
Used the 20mL graduated cylinder to measure 15mL of NaHCO3 into a large Ziploc baggy.
Using a graduated cylinder measure out and add 10 mL and of phenol red into the Ziploc bag.
Close the bag most of the way leaving a small hole to pour the vinegar in.
Add 50 mL of vinegar into the bag and seal the bag immediately.
Record your observations.
Bag #2
1. Using the graduated cylinder measure out 15 mL of NaHCO3 (baking soda) and add it to the
other clean Ziploc bag.
2. Add 30mL CaCl2 into the Ziploc bag containing baking soda.
3. Close the bag most of the way leaving a small hole to pour the phenol red in.
4. Add 25 mL of the phenol red into the bag and immediately seal the bag.
5. Record what happens.
Boyd, P.13
200312436
What Happens:
Bag one: The solution should produce yellow bubbles but the solution itself will be red once the NaHCO3
and phenol red comes in contact with the vinegar. This reaction will feel a cold. The bag needed to be
closed for bubbles will form resulting in gas. This reaction was a little slower than bag two.
Bag two: When the baking soda and CaCl2 come in contact with the red phenol yellow bubbles will form.
The bag will get warm. The solution will be yellow and there will be a yellow solid (precipitate) will be at
the bottom.
Why it Happens:
1. The formation of bubbles/gas shows a chemical reaction is occurring. NaHCO3 and vinegar produce
an endothermic reaction. It gives off cold, the bag shall be cool. As well the solution is red showing it is
basic.
Now the reason the bubble are yellow is showing that the gas (CO2) released is acidic.
If students are interested about how CO2 gas is always acidic you may want try out this lesson
(http://www.middleschoolchemistry.com/lessonplans/chapter6/lesson10)
2. Baking soda and CaCl2 produce an exothermic reaction. It gives off heat, the bag shall be warm. This
reaction is quick. The solution is yellow meaning it is acidic. The formation of the yellow gas indicates
the presence of CO2. CO2 is always acidic. A solid is formed at the bottom bag is CaCO3 (also known as
chalk).
2NaHCO3(aq) + CaCl2(aq)  CO2(g) + CaCO3(s) + 2NaCl(aq) + H2O(l)
As you can see there is NaCl is formed in this reaction. NaCl is salt. In Chemistry a salt is an ionic
compound that results from the neutralization reaction of an acid and a base.
Questions:
1.What does phenol red indicate?
-it indicated if the solution was acid or base
2. Which solution was an acid? What color did the phenol red change to?
-The baking soda and CaCl2 was an acid and the phenol red changed to a yellow color.
3. Which solution was a base? What color did the phenol red change to?
Boyd, P.14
200312436
-NaHCO3 and vinegar was a base and the phenol red stayed red.
4. Was there an endothermic or exothermic reaction present in this experiment? If there was indicate
which bag was what reaction.
- Both were present. Bag 1 was endothermic and Bag 2 was exothermic.
5. How can you tell a chemical reaction happened in this experiment?
-Bubbles formed and there was color change.
Goals / Objectives:
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Students can confidently decide when an endothermic or exothermic reaction has occurred.
Students know the warning signs of if a chemical reaction has occurred
This lab will introduce the new topic of acid and base reactions
That there are different indicators used for acids and bases (phenol red in this lab and litmus
paper in Quick Freeze)
Source:
http://webfinder.hol.es/look/Reaction_in_a_Bag_Experiment/Reaction_In_A_Bag_NaHCO3_HC2H3O2_
And_NaHCO3_CaCl2/aHR0cDovL3dlYi5jaGVtLnVjc2IuZWR1L35mZWxkd2lubi9EZW1vTGlicmFyeS9EZW1v
UERGcy9EZW1vMDIzLnBkZg==_blog
Evaluation
1) Exit slips
aim/s for the assessment
-To be completed at the end of each class and handed in
-To see what students are learning from each class
-To inquire if they want/need to know more information
The questions would be 2 factual questions that were asked that day and one question if they want
more information. This allows the teacher to see if the students understood the lab and what concepts
should be re-explained or developed further.
For example for the exit slip for the Extend Activity Reaction in a Bag (NaHCO3/HC2H3O2 and
NaHCO3/CaCl2) would be
What color does phenol red turn when it comes in contact with a base
Boyd, P.15
200312436
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It stays red
What is an exothermic reaction?
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An endothermic reaction that releases energy/heat from the environment.
Is there anything you wish to explore a bit more in depth from this experiment?
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Nope
Why is CO2 always basic?
Criteria
Exit Slip handed in
Inquiry Questions
Understand Key
Concepts
0
Has not handed
any exit slips in
Student has not
response to
inquiry questions
1
One Exit slip
handed in
Student asked
questions that
have already been
brought up in class
Is unable to
answer the factual
questions on the
Exit slips
Is able to answer 1
question correctly
on each exit slip
2
Two to Three Exit
slips handed in
Has a mixture of
class questions
and new questions
that were not
brought up in
class.
Has answered all
faction questions,
and gotten 1 or 2
questions wrong.
3
Four or Five Exit
slips handed in
New questions on
the activities that
were not already
asked in class by
the teacher.
Has answered all
factual questions
correctly
2)Comic life
Students will be warned when they are doing a comic life summary so they can take pictures of the lab.
Aim/s for the assessment
-Students are able to use their own words to summarize activities.
-A more creative way to assess over a formal lab report
-Allows students to see science is also creative and not only factual (the art in science)
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200312436
Rubric
Criteria
Summary
0
No summary is
written.
Pictures of
Experiment
No pictures are
present
Creativity and
Appearance
Blank, not creative
and poor
appearance
Graphics are
untrimmed OR of
inappropriate size
and/or shape. It
appears no
attention was
given to designing
the comic.
Design
1
Summary
describes the
information
learned but is
difficult to read
through.
2
Summary
describes the
information
learned and has a
few grammatical
errors but
information is
understandable.
1 picture of the
2 pictures of the
experiment is used experiment are
used.
Little creativity
Some creativity
and poor overall
and good overall
appearance
appearance
Graphics have
Graphics are
been trimmed to
trimmed to an
an appropriate
appropriate size
size and shape,
and interesting
but the
shape and are
arrangement of
arranged with
items is not very
some items in
attractive. It
front and others
appears there was behind. The comic,
not a lot of
however does not
planning of the
appear balanced.
item placement.
3
Summary
describes the skills
learned, the
information
learned and easy
to read and has no
grammatical
errors.
3 or more pictures
of the experiment
are used.
Very creative and
eye pleasing
appearance
Graphics are
trimmed to an
appropriate size
and interesting
shape and are
arranged well,
some in front and
some behind. Care
has been taken to
balance the comic
Comments
This assignment was difficult at the beginning because I did not have a clear focus and was going in
many different directions. Once I understood what the assignment was asking me to do. I narrowed my
focus and found suitable experiments. It really helped me see how lessons should line up and act as
scaffolding to one another. That one lesson leads to another, so you do not get confused. I really liked
taking this opportunity to find a real life application of exothermic and endothermic reactions (the
heating and cooling packs). I will consider doing learning cycles in my unit plans. Once you understand
how to use it, it makes planning easier. It also shows how much planning you have to do for only a week
of classes, pre-internship shall be fun, stressful and a learning experience.