Middle School
Feedback Sheet
UNIT # 1 Hubble Bubble
Toil & Trouble
GRADE 8 SCIENCE
Chemical Reactions
Laboratory
NAME:

General Core Targets: Completed by the student prior to submission

1. Participate safely in the laboratory
2. Gather and present data clearly
3. Identify variables within the laboratory (controlled, manipulated, responding)
4. Present the report clearly using headings to organise information
5. Justify (explain) all ideas clearly.
Student Evaluation: Completed by the student prior to submission
Signature:
Teacher Comment: Completed by the teacher once graded.
Signature:
Parent Comment: Completed by parents once graded
Signature:
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
UNIT # 1
Chemistry
Hubble Bubble Toil & Trouble
Topic Title
UNIT
QUESTION
Chemical Reactions
Grade
8
Subject(s)
Science
Can we truly ever cease to exist?
GUIDING
QUESTIONS
Assessment Task
You have been studying the chemical building blocks of matter, which included the periodic table
of elements, and in that course of study we discussed how elements could combine to form
compound substances. The readings you have completed and video you have watched has
explained how chemical reactions occur between elements/compounds to form completely new
compounds or isolate/separate elements. This laboratory will focus on observing any evidence
which suggests that a chemical reaction has occurred.
Instructions and Dates
1. Read chapter 2 sections 1& 2 of the Chemical Interactions Science Explorer text.
2. Watch the video “Physical Science Series – Chemical Reactions”.
3.Compile relevant notes in your journal.
4. Read the procedures outlined in the attached Laboratory Write Up.
5. You will be performing these series of reactions one at a time in your teams, recording your
observations as you go.
Completion of procedure: Friday October 29, 2010.
Assessment package handed out: Tuesday October26, 2010
Due date: Tuesday November 9, 2010
Specific Instructions:
 Type your report directly onto the scaffolded template. The parts you need to answer are explained in blue.
Answers need to be in typed in green.
 Always write a laboratory report in 3rd person (No use of I, we, they, you etc).
 There will be plenty of opportunities in class to discuss this report with your team and with your teacher. Set
check dates in your diary between the set date and the due date.
 Add your report to this assessment package.
 Ensure you go through the blue ‘Assessment Checklist’ before you submit this report.
AREAS OF INTERACTION
Environment/
Community & Service/
Health & Social Ed/
Human Ingenuity:
Approaches to
Learning
Human Ingenuity –
Communication
Organisational skills & Collaborative skills
LEARNER PROFILE
Risk Taker, Inquirer, Thinker
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FUNDAMENTAL
CONCEPTS
Holistic

learning
Intercultural
awareness
INTERDISCIPLINARY LINKS
None at this time
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
Level
0
Descriptors


Criterion D: Scientific Inquiry
1-2




3-4




5-6


Has not reached standard of any
descriptors below.
Attempts to identify the
purpose of investigation but
makes incomplete or
underdeveloped reference to
variables.
Suggested method is partially
complete.
Evaluation of method is absent
or incomplete.
Purpose of investigation is
recognized but provides an
underdeveloped
explanation/prediction.
Acknowledges some variables
and attempts to describe how to
manipulate them.
Method suggested is nearly
complete and includes
appropriate materials/equipment.
Evaluation is partially
developed.
Purpose of investigation is
recognized and an attempt was
made to articulate the research
question.
A simple hypothesis is formed
and explained using scientific
reasoning.
Relevant variables are identified
along with attempted
explanations of how to
manipulate them.
Comments are made regarding
reliability, validity, and
suggestions for further inquiry
(when relevant).
What level do
you think you
should get?
Explain why
Level
awarded by
your teacher
Teacher Comment
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Indicators
 You have not attempted to propose an
hypothesis
 You have not attempted to identify a variable,
which can be manipulated in some reactions.
 You have not chosen a manipulated variable
and have not explained the effect a change
would have on the responding variable.
 You have attempted to propose an hypothesis
for some reactions but have not justified them.
 You have attempted to identify a variable,
which can be manipulated in some reactions.
 In some reactions you have chosen a
manipulated variable and attempted to explain
the effect a change would have on the
responding variable.
 You have proposed an hypothesis for each
reaction but have only justified some of them.
 In most reactions you have identified a
variable, which can be manipulated.
 In most reactions you have chosen a
reasonable manipulated variable and explained
the effect a change would have on the
responding variable.
 You have clearly proposed and justified an
hypothesis for each reaction.
 In each reaction you have clearly identified a
variables, which can be manipulated.
 In all reactions you have chosen a reasonable
manipulated variable and clearly explained the
effect a change would have on the responding
variable.
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Leve
l
0
Descriptors

Criterion E: Processing Data

1-2

3-4



5-6
Has not reached standard of
any descriptors below.
Data is organized and
presented using simple
numerical or diagrammatic
forms and draws a
conclusion.
Data is organized and
transformed into numerical
and diagrammatic forms
and presented appropriately.
Conclusion is consistent
with the data.
Data is organized and
transformed into numerical
and diagrammatic forms and
presented appropriately.
Trends, patterns or
relationships are explained
including some comments on
reliability.
Indicators
 You have not highlighted and described the
evidence supporting a chemical reaction.
 You have not explained what has occurred in
each reaction.
 You have attempted to highlight and describe
the evidence supporting a chemical reaction.
 You have attempted to explain what has
occurred in each
 You have highlighted and described the
evidence supporting a chemical reaction.
 You have explained what has occurred in each
reaction highlighting the rearrangement of the
elements within the compounds involved.
 You have clearly highlighted and described the
evidence supporting a chemical reaction.
 You have clearly and logically explained what
has occurred in each reaction highlighting the
rearrangement of the elements within the
compounds involved.

What level
do you think
you should
get?
Correct conclusions are
based on reasonable
interpretation of data.
Explain why.
Teacher Comment
Level
awarded by
your teacher
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Level
Criterion F: Attitudes in Science
0
Descriptors

Has not reached standard of
any descriptors below.

Guidance and supervision is
required while using
equipment.

Needs reminders to work
cooperatively and safely.

Requires occasional guidance
with equipment

Usually pays attention to
safety and works responsibly.

Generally cooperates with
others.

Works generally
independently with precision
and skill.

Pays close attention to
safety and works responsibly.
1-2
3-4
5-6
Indicators
 You did not follow the procedures for each
reaction
 You did not work with your team, and failed to
help others when required
 You did not worked in a safe manner and had
to be removed from the lab.
 You attempted to followed the procedures for
each reaction but required help
 You sometimes worked with your team, but
failed to help others when required
 You required supervision to ensure you worked
in a safe manner, and remained on task.
 You followed the procedures for each reaction
without minimal help
 You worked with your team, helping others
when required
 You acted in a safe manner, completing the
procedure.
 You skillfully followed the procedures for each
reaction without any help
 You worked well with your team, helping
others when required
 You acted in a mature safe manner,
concentrating on completing the procedure in
a timely manner.

What level
do you think
you should
get?
Consistently works as an
effective and respectful
team member.
Explain why.
Teacher Comment
Level
awarded by
your teacher
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REACTION #1
Hydrochloric Acid (HCl)/Magnesium Lab (Mg)
Balanced Chemical Equation = 2HCl + 2Mg  2MgCl + H2
QUESTION
What will happen when a strip of magnesium is placed in a test tube of HCl?
HYPOTHESIS
I predict that if a strip of magnesium (Mg) is placed in a test tube of HCl then the magnesium will
dissolve and will form bubbles of hydrogen gas. As a result of the reaction, water vapor will also be
released. This is because when magnesium dissolves, it forms magnesium ions with a +2 charge (Mg2+) ,
and when the hydrogen atoms form H2 gas, they leave behind chloride ions. As a result the Mg2+ ions
will bond with the chloride ions.
MATERIALS
 1 test tube (numbered #1)
 10ml HCl
 1cm Mg strip
 Test tube holder
 1 pair of tweezers
PROCEDURE
1. Collect all chemicals from the central storage area.
2. At the central storage area, pour 10ml of HCl into test tube 1.
3. Take test tube 1 back to your workspace and place in the test tube rack
4. Using the tweezers drop the magnesium strip into test tube 1.
5. The teacher will pass a flame over the mouth of test tube 1.
DATA
-
There was an immediate reaction. As soon as the magnesium strip was placed into the test tube
full of hydrochloric acid, and bubbles started to form around the magnesium and rise up.
Magnesium started to change color, white, combining with the hydrochloric acid.
Magnesium started spinning upwards towards the surface.
In the end, the magnesium strip disappeared entirely.
When a flame was passed over the mouth of the test tube, the reaction between the flame and the
hydrogen gas, caused a popping noise.
After four days…
-
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No change has occurred.
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What evidence did you notice, which would suggest a chemical reaction, has taken place? Highlight the
relevant descriptors below.
Bubbles
Heat (exothermic)
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Precipitate
Colour Change
Cold (endothermic)
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ANALYSIS
Explain your data. Explain why the changes occurred as described in the data. Make sure you use all
relevant vocabulary in your description.
A chemical reaction occurred when a magnesium strip was placed into a test tube of hydrochloric acid,
the molecules have been rearranged because color change, bubbles and an exothermic reaction have
occurred. Evidence can be gathered when referring back to the balanced chemical equation, 2HCl +
2Mg  2MgCl + H2. By looking at the equation, conclusions can be drawn by how the substances have
been rearranged to form new substances. Color change has occurred here because when the magnesium
strip reacted with the chloride it caused it to turn to a white color. The hydrogen gas escaping from the
solution caused the bubbles to rise up from the bottom of the test tube. And finally the exothermic
reaction was caused by the combination of the both the flame and the hydrogen gas inside of the test
tube.
Suggest a variable that could be changed and predict the result.
This lab was a demonstration lab so it wasn’t really an experiment. However, it was supposed to be an
experimental lab, than a manipulative variable that could be changed could be the concentration of
hydrochloric acid that was used. This way the different effects of each concentration on the magnesium
strip could be seen and you could also see if each concentration had a significant difference or not. I
predict that if a higher concentration of hydrochloric acid was added then more bubbles would be
released and the magnesium strip would have spun around faster and disappeared more quickly.
CONCLUSION
Has your hypothesis been proved or disproved. Why? What evidence did you observe to support this
statement?
The hypothesis for reaction one was partially correct. In summary, the hypothesis states that if a strip of
magnesium is placed in a test tube of hydrochloric acid, then the magnesium will dissolve and form
bubbles of hydrogen gas. As a result of the reaction, water vapor will also be released. All of this
statement is true, however, it does leave gaps in certain areas. For instance, the hypothesis didn’t state
that the magnesium strip would have a color change, and it also did not state that there would end up
being an exothermic reaction. However, in this reaction data was collected stating that bubbles
(hydrogen gas) were released from the surface of the magnesium strip and also that the magnesium will
end up dissolved. The fast moving molecules in the solution are the reason an exothermic reaction
occurred. To conclude, this hypothesis is only partially correct, therefore it is inaccurate.
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REACTION # 2
Water (H2O)/Magnesium Lab (Mg)
Balanced Chemical Equation = 2H2O + Mg  Mg(OH)2 + H2
QUESTION
What will happen when a strip of magnesium is placed in a test tube of
H2O?
HYPOTHESIS
I predict that if a strip of magnesium (Mg) is placed in a test tube of water (H2O) then slowly bubbles of
hydrogen will start to form on the surface of the magnesium strip therefore causing the magnesium strip
to float to the surface. Magnesium hydroxide is formed as a very thin layer on the magnesium and this
usually stops the reaction. This is because magnesium hydroxide forms on the magnesium like a barrier
since magnesium is almost insoluble with water because like most metals when reacting with water the
metal hydroxide is produced, and the reaction between the magnesium strip and the water will break the
bond between the two hydrogen molecules. A bond between one of the hydrogen atoms and the oxygen
atom and the magnesium will form and hydrogen will then be released in the form of gas bubbles.
MATERIALS
 1 test tube (Numbered #2)
 10ml H2O
 1cm Mg strip
 Test tube holder
 1 pair of tweezers
PROCEDURE
1. Collect all chemicals from the central storage area.
2. At the central storage area, pour 10ml of H2O into test tube 2.
3. Take test tube 2 back to your workspace and place in the test tube rack
4. Using the tweezers drop the magnesium strip into test tube 2.
DATA
-
The magnesium sunk to the bottom of the test tube.
There was no immediate reaction and the only change that happened were small bubbles forming
on the surface of the magnesium and slowly rising up to the top of the solution.
After a small period of time, the amount of bubbles rising up increases, but there is only a slight
difference.
After four days…
-
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The metal is slightly bent around the ends.
There are scrapes that look slightly like bite marks on the surface of the magnesium strip.
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What evidence did you notice, which would suggest a chemical reaction, has taken place? Highlight the
relevant descriptors below.
Bubbles
Heat (exothermic)
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Precipitate
Color Change
Cold (endothermic)
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ANALYSIS
Explain your data. Explain why the changes occurred as described in the data. Make sure you use all
relevant vocabulary in your description.
A chemical reaction occurred when a strip of magnesium was placed in a test tube of water. This can be
proven by the observational things occurring: bubbles forming, the strip of magnesium changed colors
from black to white and the magnesium hydroxide (a precipitate) was formed on the surface of the
magnesium. The bubbles formed because the chemical reaction caused the bond between the hydrogen
atoms and the oxygen atoms to break, and the magnesium bonded as well with two hydrogen atoms and
two oxygen atoms, therefore the hydrogen was dislocated from the solution in the form of bubbles.
Another observation was that the magnesium changed colors from black to white, because in the
beginning, the magnesium was isolated from the rest of the solution and was originally black, however
when the reaction occurred the magnesium bonded with the hydrogen and the oxygen causing the
magnesium hydroxide to form on the surface of the magnesium which caused the magnesium to change
colors from black to white. This was the end of the reaction because magnesium hydroxide is incapable
of dissolving in water.
Suggest a variable that could be changed and predict the result.
If this reaction were to be an individual experiment then a manipulative variable for this experiment
could possibly be a different substance to submerge in the H2O. In this experiment, a strip of
magnesium was dropped into a test tube of H2O. To change it around and to find a different result,
instead of putting a strip of magnesium into the water, you could place a strip of aluminum or another
form of metal. This way you could compare and see how the hydrogen and the oxygen react to different
forms of metal and if the reactions are similar to one another or very different. I predict that if aluminum
foil was added to the H2O instead of the magnesium strip then the aluminum would probably end up
having a pretty similar reaction to the water, small bubbles would form and the edges of the foil would
be slightly bent and dented.
CONCLUSION
Has your hypothesis been proved or disproved. Why? What evidence did you observe to support this
statement?
For this experiment my hypothesis, in summary, states that if a strip of magnesium is placed in a test
tube of water then slowly bubbles of hydrogen will start to form on the surface of the magnesium and
then magnesium hydroxide will form as a very thin layer of the magnesium and this will stop of the
reaction. This is because magnesium hydroxide forms on the magnesium like a barrier, which stops the
reaction. This statement explains what happened during the reaction in general. During the reaction,
observations were made stating that bubbles were released from the surface of the magnesium, which
then later on cased the magnesium to float to the surface. The hypothesis also states that magnesium
hydroxide formed on the surface of the magnesium, which ended up causing a color change from black
to white. The one observation that was made that the hypothesis did not state was that there was scape
(bite) marks on the surface of the magnesium. This happened four days after the reaction so it could’ve
been a observation specific to only one group or it could have had something to do with the reaction
between the hydrogen and oxygen and the magnesium strip.
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REACTION # 3
Silver Nitrate (AgNO3)/Copper (Cu)
Balanced Chemical Equation = AgNO3 + Cu  Cu(NO3)2 + Ag
QUESTION
What will happen when a strip of Copper is placed in a test tube of Silver
Nitrate?
HYPOTHESIS
If you place a strip of Copper in a test tube of Silver Nitrate, then I predict that the copper will stay the
same color but on top of the copper a layer of silver will form on the surface. This is because I believe
that the copper ions will reduce the silver ions to silver, and the silver crystals will coat the surface of
the copper. At the beginning of the solution the solution will be colorless, but in less than one hour the
solution will be a light blue and the wire will be covered with silver needles. This is because, copper
metal will become copper ions in the solution and silver ions will become silver metal.
MATERIALS
 1 test tube (Numbered #3)
 10ml AgNO3
 1cm Cu strip
 Test tube holder
 1 pair of tweezers
PROCEDURE
1. Collect all chemicals from the central storage area.
2. At the central storage area, pour 10ml of AgNO3into test tube 3.
3. Take test tube 3 back to your workspace and place in the test tube rack
4. Using the tweezers drop the Cu strip into test tube 3.
DATA
-
No immediate reaction.
The copper strip started to gradually change color from copper to dull silver.
Over time, you were able to see the silver nitrate reacting to the copper, created a type of moss
like coating around the copper strip, making the color lighter and more silver.
Silver needles continued to form until the entire copper strip was covered. If you examined
closely you could see the crystals forming.
After a while, the silver nitrate gradually turned a pale blue.
After four days…
-
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The silver needles are still coated around the copper strip.
If you shake the test tube around a little, the silver falls off and you can still see that the copper
strip has the same color. The moss like material remains in the same form.
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What evidence did you notice, which would suggest a chemical reaction, has taken place? Highlight the
relevant descriptors below.
Bubbles
Heat (exothermic)
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Precipitate
Color Change
Cold (endothermic)
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ANALYSIS
Explain your data. Explain why the changes occurred as described in the data. Make sure you use all
relevant vocabulary in your description.
A chemical reaction occurred when a strip of copper was placed in a test tube of silver nitrate. The
observational things occurring can prove this: the solution changing from a transparent clear color to a
pale blue and the silver precipitate that formed around the around the copper strip creating a moss like
coating. The color change was caused by the reaction the copper had with the silver nitrate, causing the
silver nitrate to change to a pale blue in less then an hour. Another observation was that the copper strip
ended up having silver needles attached to the surface. This is because the nitrate and silver separated
and when the nitrate formed with the copper, the silver was left on its on and then it formed in a
precipitate around the surface of the copper. If you refer back to the chemical equation: AgNO3 + Cu 
Cu(NO3)2 + Ag, you can see that when the copper and the nitrate mixed to together it formed the pale
blue substance and the copper ions reduced the silver ions to silver and the silver crystals ended up
coating the surface of the copper.
Suggest a variable that could be changed and predict the result.
If this reaction were to be an individual experiment then a manipulative variable for this experiment
could possibly be a different form of nitrate, for example gold nitrate. In this experiment, a strip of
copper was dropped into a test tube of silver nitrate. To change it around and to find a different result,
instead of putting a strip of copper into a test tube of silver nitrate, you could place a strip of copper into
a test tube of gold nitrate. This way you could compare and see how the gold nitrate and the copper react
with one another and if using the silver nitrate and the gold nitrate would have similar or different
results. I predict that if a strip of copper was submerged in a test tube of gold nitrate then the gold and
the nitrate would detach from one another and the gold would form a precipitate around the copper in
the form of gold.
CONCLUSION
Has your hypothesis been proved or disproved. Why? What evidence did you observe to support this
statement?
For this experiment my hypothesis, in summary, states that if you place a strip of copper in a test tube of
silver nitrate, then I predict that a layer of silver will form on the surface and the solution will end up
changing from a transparent liquid to a pale blue solution. This is because the copper ions will reduce
the silver ions to silver and the silver crystals will coat the surface of the copper. This statement explains
what happened during the reaction in general. During the reaction, observations were made stating that
there was no immediate reaction but gradually silver started to form on the surface of the copper but it
wasn’t obvious until there was a lot already formed. Over time however, more and more needles started
to form and the solution even started changing color to a pale blue. After four days there were no
dramatic changes, however, after shaking the tube, the silver substances fell off of the copper, and you
could see the actual color of the copper was the same. To conclude, the hypothesis was correct and
specific to what happened in the reaction.
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REACTION # 4
Copper Sulfate (CuSO4)/Aluminum Lab (Al)
Balanced Chemical Equation = CuSO4 + Al  Al(SO4) + Cu
QUESTION
What will happen when a strip of Aluminum is placed in a test tube of
CuSO4?
HYPOTHESIS
If a strip of aluminum (Al) is placed in a test tube of CuSO4, I predict that the ending result will be a
white powder (aluminum sulfate), because an electrochemical reaction will take place and an ionic bond
will from between the sulfate and the aluminum causing the bond between the copper and sulfate to
break. Thus the bond between copper and sulfur will be broken, the sulfate and the aluminum will form
an ionic bond copper will be displaced.
MATERIALS
 1 test tube (Numbered #4)
 10ml CuSO4
 1cm Al strip
 Test tube holder
 1 pair of tweezers
PROCEDURE
1. Collect all chemicals from the central storage area.
2. At the central storage area, pour 10ml of CuSO4 into test tube 4.
3. Take test tube 4 back to your workspace and place in the test tube rack
4. Using the tweezers drop the magnesium strip into test tube 4.
DATA
-
The aluminum sunk to the bottom of the test tube.
After a short period of time, small bubbles began to form on the aluminum and the amount of
bubbles escaping started to increase.
After four days…
-
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The aluminum foil has is the same color but there are rust (copper) like holes and marks on the
foil.
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15
What evidence did you notice, which would suggest a chemical reaction, has taken place? Highlight the
relevant descriptors below.
Bubbles
Heat (exothermic)
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Precipitate
Colour Change
Cold (endothermic)
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ANALYSIS
Explain your data. Explain why the changes occurred as described in the data. Make sure you use all
relevant vocabulary in your description.
A chemical reaction occurred when a piece of aluminum foil was placed in a test tube of copper
sulphate. The observational things occurring can prove this: small bubbles formed when the aluminum
was placed in the CuSO4 and after four days copper colored holes were formed in the aluminum cutting
out parts of the foil. If you refer back to the chemical equation: CuSO4 + Al  Al(SO4) + Cu, evidence
can be gathered backing up the observations that were made. After the aluminum foil was placed in the
copper sulphate, the copper and sulphate separated from one another and the copper formed a precipitate
in the aluminum.
Suggest a variable that could be changed and predict the result.
If this reaction were to be an individual experiment then a there would be two good possible
manipulative variables for this experiment. One variable could be the type of metal they put in the
copper sulphate, for example instead of aluminum they could put in magnesium or copper. I predict that
the result would be similar, however, magnesium and copper are both thicker materials, so the sulphate
might not burn all the way through them, like it did for the aluminum. Another variable could be the
concentration of sulphate that was put into the test tube. If the concentration increased, then I would
predict that more holes in the aluminum would form, and if the concentration decreased then I would
predict that less holes would form in the aluminum. If you used these manipulative variables you could
compare and see the changes that would be made to this experiment.
CONCLUSION
Has your hypothesis been proved or disproved. Why? What evidence did you observe to support this
statement?
For this experiment my hypothesis, in summary, states that if you place a strip of aluminum in a test
tube of copper sulfate then the ending result will be a white powder, because an electrochemical reaction
will take place and an ionic bond will form between the sulfate and the aluminum causing the bond
between the copper and sulfate to break. The hypothesis was incorrect. The aluminum did not change to
white powder, it remained in its original form and the only change to it was the copper colored holes
burned through the middle.
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REACTION # 5
Ammonia (NH3)/Copper Sulphate (CuSO4)
Balanced Chemical Equation = NH3 + CuSO4 
[ Cu (NH3)4 ] +2 +(SO4)
QUESTION
What will happen when Ammonia is mixed with Copper Sulphate?
HYPOTHESIS
If Ammonia (NH3) is mixed with Copper Sulphate (CuSO4), then I predict that the solution will go
from being a transparent light blue to an even darker blue depending on how much copper sulphate is
added to the ammonia. This is because the reaction ammonia has with the copper sulphate causes it to
change to this color. The sulphate will also separate itself from the copper and form a solid suspension
on the bottom of the test tube.
MATERIALS
 1 test tube (Numbered #5)
 1 Graduated cylinder
 10ml CuSO4
 10ml NH3
 Test tube holder
PROCEDURE
1. Collect all chemicals from the central storage area.
2. At the central storage area, pour 10ml of NH3 into test tube 5
3. At the central storage area, pour 10ml of CuSO4 into the graduated cylinder
4. Take test tube 5 and the graduated cylinder back to your workspace and place test tube 5 in the test
tube rack.
5. Slowly pour the NH3 into test tube 5
DATA
-
After the NH3 was poured into the CuSO4 the solution immediately changed from light blue to
dark blue.
A white substance (possibly solid) started falling to the bottom of the test tube. You could also
see an area between the dark blue substance and the white solid substance which was a blend
between the two substances causing a light blue color.
After four days…
-
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There was no white solid underneath the blue liquid, instead all of it was a light blue liquid.
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18
What evidence did you notice, which would suggest a chemical reaction, has taken place? Highlight the
relevant descriptors below.
Bubbles
Heat (exothermic)
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Precipitate
Colour Change
Cold (endothermic)
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19
ANALYSIS
Explain your data. Explain why the changes occurred as described in the data. Make sure you use all
relevant vocabulary in your description.
A chemical reaction occurred when ammonia was mixed with copper sulphate. The observational things
occurring can prove this: when the ammonia was poured into the copper sulphate, the solution
immediately changed from colorless to a very dark blue, there was also a light blue precipitate, possibly
a solid, suspended on the bottom of the test tube. If you refer back to the chemical equation: NH3 +
CuSO4  [ Cu (NH3)4 ] +2 +(SO4), you can see that when the ammonia and the copper sulfate were
mixed together, the copper and the nitrate separated from each other and the copper and the ammonia
reformed together which caused the solution to change from transparent to dark blue. Another
observation was that on the bottom of the dark blue substance a light blue substance also formed. The
copper and the sulfate also detached from each other and the sulphate reformed at the bottom of the blue
substance in a blue form. This took time, but after four days it was fully formed.
Suggest a variable that could be changed and predict the result.
If this reaction were to be an individual experiment then a manipulative variable for this experiment
could possibly be a different type of sulphate, instead of copper sulfate. In this experiment, ammonia
and copper sulfate were mixed together in a test tube. To change it around and to find a different result,
instead of putting ammonia in copper sulfate, you could mix ammonia with hydrogen sulfate or ferrous
sulfate. This way you could compare and see how the different forms of sulfate and the ammonia react
with one another and if using different sulfates have similar or different results. I predict that if ammonia
is mixed with a different form of sulfate, it would not turn blue, but the precipitate would still form at
the bottom because the sulfate would still detach itself and form by itself again.
CONCLUSION
Has your hypothesis been proved or disproved. Why? What evidence did you observe to support this
statement?
For this experiment my hypothesis, in summary, states that if ammonia is mixed with copper sulphate,
then the solution will go from being a transparent light blue to an even darker blue depending on how
much copper sulphate is added to the ammonia. This is because the reaction ammonia has the copper
sulfate causes it to change to this color. The sulfate will also separate itself from the copper and form a
solid suspension on the bottom of the test tube. This statement explains what happened during the
reaction in general. During the reaction, observations were made stating that there was an immediate
reaction and as soon as the ammonia was poured into the copper sulfate the solution immediately
changed to a dark blue. However, it took some time for the precipitate to form at the bottom of the test
tube. There was no evidence that the precipitate was a solid, however, it is probable. After waiting four
days there were no changes and the solution stayed the same. To conclude, the hypothesis was correct
and specific to what happened in the reaction.
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REACTION # 6
Hydrogen Peroxide (H2O2)/Yeast
Balanced Chemical Equation = 2H2O2  2H2O + O2
QUESTION
What will happen when yeast is placed in a flask of Hydrogen Peroxide?
HYPOTHESIS
If yeast is placed in a flask of Hydrogen Peroxide, then I predict that bubbles will form and the
molecules will spread, being less dense and taking up more space.
MATERIALS
 1 flask (125ml)
 1 rubber stopper
 25ml H2O2
 ½ teaspoon yeast
 ½ A4 sheet of paper
 1 tooth pick
 1 lighter
PROCEDURE
1. Ensure you collect all chemicals from the central storage area.
2. At the central storage area, pour 25ml of H2O2into the flask
3. At the central storage area, collect the yeast and place onto the ½ A4 paper
4. Take the flask and the yeast cylinder back to your workspace
5. Slowly pour the yeast into the flask.
6. Once all the yeast is in the flask, place the stopper into the opening.
7. Set the tip of the tooth pick on fire with the lighter and let it burn for a few seconds then blow it out.
Ensure the tip of the tooth pick is still glowing.
8. Remove the stopper from the flask and insert the glowing end of the tooth pick well into the flask
without letting go. Observe what happens.
9. Remove the tooth pick and replace the stopper.
10. Repeat steps 7 to 9 as many times as you can.
DATA
-
Immediately a lot of foam started to rise up and even after a cork was placed at the top of the
flask, foam continued to rise up through the cracks.
After a while the foam sunk down and the liquid decreased by a lot.
After the toothpick was lit and blown out, once it was placed in the flask it lit up again.
The flask was hot when you touched it.
After four days…
- No change has occurred.
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What evidence did you notice, which would suggest a chemical reaction, has taken place? Highlight the
relevant descriptors below.
Bubbles
Heat (exothermic)
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Precipitate
Colour Change
Cold (endothermic)
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ANALYSIS
Explain your data. Explain why the changes occurred as described in the data. Make sure you use all
relevant vocabulary in your description.
If you refer back to the balanced chemical equation: 2H2O2  2H2O + O2, you will see that no
chemical reaction occurred.
Suggest a variable that could be changed and predict the result.
If this reaction were to be an individual experiment then a manipulative variable for this experiment
could be the temperature that the hydrogen peroxide was heated at. In this experiment, yeast was placed
in a flask of hydrogen peroxide. To change it around and find a different result, the temperature could
change. We could see what the reaction was at a cold temperature, room temperature and boiling
temperature. This way you could compare and see how the different temperatures of hydrogen peroxide
affect the result, and if the result is similar or different. I predict that the hotter the temperature is, the
more the yeast will rise and the more foam will form.
CONCLUSION
Has your hypothesis been proved or disproved. Why? What evidence did you observe to support this
statement?
For this experiment my hypothesis, in summary, states that if yeast is placed in a flask of hydrogen
peroxide, then I predict that bubbles will form and the molecules will spread, being less dense and
taking up more space. This statement explains what happened during the reaction in general. During the
reaction, observations were made stating that there was an immediate reaction and a lot of foam started
to rise up to the top of the flask. Even after a cork was placed at the top of the flask, foam continued to
rise up through the cracks. After four days no observational change had occurred. To conclude, although
vague, my hypothesis was correct, however not specific to what happened during the reaction.
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