Mixtures and Solutions - LESSON 5
Fifth- Sixth Grade
INTENDED CURRICULUM
BIG IDEA: (display in class during the lesson)
Elements and their combinations account for all the varied types of matter in the world.
Establish working word wall throughout the lesson.
Chemical Reactions, Reaction Products, and Reaction in a Zip Bag
Investigation: 4.1, 4.2, 4.3 of Mixtures and Solutions
Idaho Standard(s) addressed
LESSON CONTENT GOALS
GUIDING QUESTIONS
1) A chemical reaction is a change that
results from mixing two or more
materials. A reaction results in new
products.
1) What causes a chemical reaction ?
2) Examples of observable measurable
changes in some chemical reactions
include: bubbling, formation of
precipitates, temperature changes, and
fizzing.
2) How do we know if a
chemical reaction has taken place?
3) A chemical compound is formed when
two or more substances (reactants) are
joined together chemically creating
new substances (products) with
different properties
.
3) How can we prove that a new
substance has formed?
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IMPLEMENTED
CURRICULUM
Teacher’s Notes
The objective for this lesson is to have students understand that when mixing two substances in
a chemical reaction, the products are different. Students will see how the substances they mix
produce different observable effects and the final products they end up with may be different.
Students will use baking soda (sodium bicarbonate), calcium chloride and citric acid. Baking
soda is commonly used as a baking agent, for fire extinguishers, as an antacid, and as a
deodorant in refrigerators. Calcium chloride is used for melting ice on roads and sidewalks,
reducing dust on dirt roads and as a drying agent. Citric acid is a common food additive.
All three materials dissolve in water to form solutions. Baking soda is the least soluble of the
three. When calcium chloride forms a solution, heat is given off. When baking soda or citric
acid dissolves in water, the solutions become cooler; energy is needed to break the bonds
holding the molecules together.
When calcium chloride and sodium bicarbonate (baking soda) are mixed together in water, the
mixture fizzes slowly, turns milky white, cools, and releases bubbles. Changes are happening.
An insoluble white precipitate – calcium carbonate (also known as chalk) forms and settles to the
bottom of the container; sodium chloride (also known as table salt) forms but stays dissolved in
the water; and a colorless gas (carbon dioxide) forms bubbles, which rise to the surface. These
changes are all evidence of a chemical reaction. The mixed calcium chloride, baking soda, and
water make an acid solution. Bromythymol blue works well, changing from a blue to a yellow.
Red cabbage juice (made by boiling the leaves of red cabbage) may be used if Bromythymol
blue is not available. Cabbage juice starts off blue or violet and changes to bright pink. There are
no special safety considerations for any of these indicators.
Calcium carbonate (chalk) does not dissolve in water, so it can be filtered out. Salt does
dissolve in water so it can not be filtered out. The gas escapes. The salt can be recovered
through evaporation. Unless measures are taken to capture the carbon dioxide as it is released
from the reaction, it is lost.
When citric acid and baking soda are mixed together in water, the mixture bubbles and froths
rapidly, then settles down to a clear liquid. This reaction also produces new materials, but the
only one we can observe is the carbon dioxide in the form of bubbles. The other new materials
are soluble in water and form a solution of sodium citrate.
When calcium chloride and citric acid are mixed together in water there is no evidence of a
reaction. Both materials merely dissolve in water.
When all three materials are mixed together and then water is added, something very
interesting happens. The mixture fizzes and turns clear, as in the reaction of citric acid and
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baking soda. Very slowly the mixture will turn milky white as a solid precipitates from the
reaction. The precipitate forms a crust on the surface, but cannot be easily crushed into a
powder. This precipitate is calcium citrate, a material that does not have an everyday
application.
This lesson will take at least 5 days to complete.
Advanced Preparation:
Set up materials for 2 stations with containers of the three chemicals: calcium chloride, baking
soda, and citric acid;
Label the measuring spoons students will use for the chemicals. Leave the spoon inside
each container so they won’t contaminate them.
With a permanent marker, mark the zip lock bags 1, 2, 3 for the groups.
Dilute 5 ml bromothymol blue provided in the kit with 2 cups of water. If not available red
cabbage juice (made by boiling the leaves of red cabbage) works just as well.
Have the 8 evaporating dishes ready in the trays for Part II, plus 8 more dishes for the powder.
Materials needed for a group of 4 students:
For Part I
3 zip lock bags marked 1, 2, 3
50 ml water
4 hand lenses
1 syringe (in Measurement Kit)
1 spoon of baking soda
1 spoon citric acid
1 spoon calcium chloride
TEACHER WILL NEED For Part II
1 evaporating dish
1 funnel
1 filter
vinegar
1 FOSS tray
dropper
1 pitcher with water & BB drops or red cabbage
juice
STUDENTS WILL USE THE ZIP LOCK BAGS TO MIX THEIR SUBSTANCES instead
of cups. The bags will expand when carbon dioxide is produced from the reaction. Make
sure the bags are marked with a permanent marker so they will not be confused.
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LESSON OVERVIEW
Brief Planning:

Read engaging scenario.

Discuss the problem based on engaging scenario and record it in the notebooks.

Discuss the way to solve the problem with groups, and then class records a class focus
question.

Discuss the chemicals used in the scenario and plan how to mix them.

Guide students in the creation of Chart 1 so everyone is testing at the same time.

Show students bags labeled 1, 2, 3.The order should be
1) calcium chloride with baking soda
2) calcium chloride with citric acid
3) baking soda with citric acid.

Demonstrate how Bromothymol Blue or red cabbage juice changes color when in contact
with CO2.

Demonstrate how to place the chemicals and water inside the bag and seal it immediately.

Safety Reminder: keep the lid on the calcium chloride when container is not in use.

Teacher will
o filter the precipitate left in bag 1
o place the liquid in 8 evaporating dishes
o place the powder in the filter in another 8 dishes.

Students make chart to record observations of substances left on filter and evaporating
dish.

To identify the powder left in filter students observe how vinegar reacts with chalk and
then with the powder in filter.

Making meaning conference (1) directed by teacher with claims based on evidence
students recorded in chart 1.

Check substances left in filter paper and evaporation dishes and record observations in
Chart 2.

Making Meaning Conference (2) with data from chart 2.

Claims and Evidence: write claims and evidence focusing on the guiding questions.
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
Conclusions: write sentences on how the evidence supported the prediction.

Reflection: write a chemical word equation showing what happened in bag one, write a
definition of a chemical reaction. Write an investigable question that will allow for
further investigation.
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DAY ONE: ENGAGING SCENARIO
Use the template at the end of this lesson to make a transparency or copies for students to read
along.
“From Lesson 4 we now know that mixtures can be separated, even salt water solutions.
We were able to solve the problem, thanks to you. But I have another challenge for you.
I have 3 chemicals (show the containers) When two of the three are mixed together with
water they form a solution. But I do not know which ones to mix. I also know that when
two of these are mixed a chemical reaction occurs. I need to know which two produce
this reaction. The product or result I get is CO2, a chemical compound you are familiar
with. This is totally different from the original substances, which I cannot get back now.
The chemicals I have are: Baking soda (NaH CO3), Calcium Chloride (Ca Cl) and
citric acid (C6 H8 O7).
How can I solve my problem?”
Word Wall
Chemical reaction: when two or more elements join to form products with
different properties. A piece of evidence that a chemical reaction has taken place is
the release of gases or changes in temperature
Word Wall
Calcium chloride, citric acid, and backing soda examples of chemical compounds
FOCUS QUESTION (display, discuss by groups, record in notebooks)
Teacher says: “Let’s summarize what we heard in the scenario. First we need to know
which two chemicals will form a solution. Second we need to know which two chemicals will
form a chemical reaction when mixed. A chemical reaction happens when the chemicals are
mixed and we get something that is different than what we started with. We have three
chemicals: baking soda, citric acid, and calcium chloride.” (Write the names and chemical
formulas on the board.)
Teacher’s notes: Once the scenario is clarified, have students discuss with their group the focus
question and record it in their notebook. Have them share their ideas with the class. If a group
has problems with the focus question have them use the suggested class focus question below.
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Make sure they record it as the class focus question. Remember to give feedback for each
notebook component as you check them.
Suggested class focus question:
How can we determine which chemicals form a solution when mixed, and which
combinations produce a chemical reaction?
Check and provide feedback
PREDICTION (discuss by groups, record in notebooks)
As students finish writing their focus question, have them begin their discussion on how to solve
the problem. Allow some time for discussion. Display the materials they will use for this
investigation so they can decide how to solve their problem. Supervise while students are writing
their predictions and planning. Have students share their ideas. Reject or decline those that are
not safe or appropriate. Guide them to test the materials as safely as possible.
Prediction: (optional format)
If you mix baking soda and calcium chloride then you will get a solution because
there is Na in the substance and maybe it forms salt because salt has sodium and chlorine as
its parts.
I think that if calcium chloride and citric acid are joined we will get a chemical reaction
because the acid has the same elements as sugar.
Check and provide feedback
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DAY TWO: DATA CHART 1 (record in notebooks)
As the groups finish sharing predictions with the class they should decide on the way they will
test and organize their observations and data. Offer suggestions on how they can do this.
Teacher says, “I want to help you organize your data charts. What do we put in the first column
of our chart? The substances that we are going to mix. Let us do that. But which substances
should we put first?
Allow them time to discuss, have them share their ideas and record them on the board.
Teacher says, “I suggest that we try the following so we all know what we are testing and can
label them with numbers.”
1) Baking soda (NaH CO3) + Calcium Chloride (Ca Cl) + water (H2O)
2) Calcium Chloride (Ca Cl) + citric acid (C6 H8 O7) + water (H2O)
3) Baking soda (NaH CO3) + citric acid (C6 H8 O7) + water (H2O)
Sample data chart. Do not share what should be observed with the students.
Substances and Chemical Formulas
Observations
baking soda
calcium chloride
+ water
NaH CO3
Ca Cl
H 2O
NOTE: What to look for:
Fizzing, cloudy or milky white,
white material settles to the
bottom
2
calcium chloride
citric acid
+ water
Ca Cl
C6 H8 O7
H2O
NOTE: What to look for:
Clear, solid dissolves, no reaction
3
baking soda
citric acid
+ water
NaH CO3
C6 H8 O7
H2O
NOTE: What to look for:
Fizzing, clear solution
1
TEACHER NOTE: STUDENTS SHOULD OBSERVE CHANGES IN COLOR AND
TEMPERATURE, AS WELL AS SOME FIZZING. DO NOT TELL THEM THIS
BEFOREHAND.
In Bag #1
When calcium chloride and sodium bicarbonate (baking soda) are mixed together in water, the
mixture fizzes slowly, turns milky white, cools, and releases bubbles. Changes are happening.
An insoluble white precipitate – calcium carbonate (also known as chalk) forms and settles to the
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bottom of the container; sodium chloride (also known as table salt) forms but stays dissolved in
the water; and a colorless gas (carbon dioxide) forms bubbles, which rise to the surface. These
changes are all evidence of a chemical reaction. The mixed calcium chloride, baking soda, and
water make an acid solution. Bromythymol blue works well, changing from a blue to a yellow.
Red cabbage juice (made by boiling the leaves of red cabbage) may be used. Cabbage juice starts
off blue or violet and changes to bright pink. There are no special safety considerations for any
of these indicators.
Calcium carbonate (chalk) does not dissolve in water, so it can be filtered out. Salt does
dissolve in water so it can not be filtered out. The gas escapes. The salt can be recovered
through evaporation. Unless measures are taken to capture the carbon dioxide as it is released
from the reaction, it is lost.
In Bag #2
When calcium chloride and citric acid are mixed together in water there is no evidence of a
reaction. Both materials merely dissolve in water.
In Bag #3
When citric acid and baking soda are mixed together in water, the mixture bubbles and froths
rapidly, then settles down to a clear liquid. This reaction also produces new materials, but the
only one we can observe is the carbon dioxide in the form of bubbles. The other new materials
are soluble in water and form a solution of sodium citrate.
Instructions for demonstration of Bromothymol Blue or red cabbage juice
Teacher says: “How are we going to know if we have made the gas CO2?” We will see bubbles,
or air coming out.
Teacher says, “Here is something that may help. Remember this blue liquid is BB?
What happens when I blow on it? Change color. What does the change in the BB indicate? That
CO2 is present. How can we use BB in our investigation?
We can place a couple of drops of BB in the water we will use to mix the chemicals. How
will you know if the mixture has CO2 ? If the liquid changes to yellow or light green.
The BB has to be mixed with the water so some drops of it are already in the water you will use
in your. Now we need to know how much water and the amount of the chemicals we will use.”
Note: Red cabbage juice starts off blue or violet and changes to bright pink.
FURTHER INSTRUCTIONS
Teachers says, “We will use only ONE spoonful of each substance. NO MORE than a spoonful.
The spoons are labeled so you do not get them mixed. There is one for each chemical.
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Teaching Notes:
Each substance should have its own spoon. They should not be contaminated by switching
spoons. LABEL THE SPOONS to avoid problems. Have them leave the spoon inside the
container once they have their chemical.
Read the instructions to students and demonstrate how to do it.
Make copies of the instructions below FOUND AT THE END OF THE LESSON so
students can follow them as they do their lab.
LAB INSTRUCTIONS
1. Put one spoonful of each of the chemicals baking soda (NaH CO3 ) + calcium chloride (Ca Cl )
in the ziplock bag #1.
2. Fill the syringe with the 25 ml of water that you can get from the materials station..
3. Close the zip bag, but leave an opening big enough to insert, or put in, the syringe.
4. PRESS ALL THE AIR OUT OF THE BAG.
5. QUICKLY add the 25 ml of water to the mixture, remove syringe and
close the bag immediately.
6. Gently shake the bag and record what you observe.
7. DO NOT OPEN THE BAG AT ANY TIME.
8. Carefully put the bag aside and begin testing the next pair of chemicals.
9. Repeat the same instructions for bags #2 [calcium chloride (Ca Cl) + citric acid (C6 H8 O7)]
and #3 [ (baking soda (NaH CO3 )+ citric acid (C6 H8 O7)].
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DAY THREE
Word wall:
Fizzing: making zzzz sounds
Bubbling: making bubbles
START THE INVESTIGATION
Once students have a chart ready and have understood the instructions remind them that they will
need to record everything they see, hear, or feel. Allow them to begin testing and supervise to
see that they are following directions. Have them use appropriate words for describing what they
see, hear, and feel in the bags.
TEACHER’S NOTES FOR FILTERING PRECIPITATE IN BAG ONE AND
EVAPORATING SOLUTION.
As students test and record their observations collect one sample of each of the bags to discuss
during the Making Meaning Conference.
There should be general agreement that bag #2 (calcium chloride and citric acid) formed a
solution and that bag #3 (baking soda and citric acid) formed a solution when it stopped fizzing,
bag #1 (baking soda and citric acid) will be the most controversial. Some may claim that it is not
a solution because of the white substance that settled out, some may suggest that bag #1 has a
solution with some white substance in it. Both are valid positions. This is why the vinegar test
is used with bag #1 on Day 4. (Vinegar will react by bubbling with the calcium carbonate
precipitate.)
Take an additional sample of bag #1 and filter the substance so the precipitate stays on the filter.
Place it outside to dry. Take the liquid substance from bag 1 and distribute it among 8
evaporating dishes. Set this aside for the follow day. Students will use these materials to observe
the dry substance that formed from the mixture and investigate with vinegar.
There is no new substance in bag #2, just merely a solution of citric acid and calcium chloride.
You may filter these and find that there were no materials in the filter paper and then evaporate
the solution to see what you will find with the dry substance and vinegar.
In bag #3 the reaction also produces new materials, but the only one we can observe is the
carbon dioxide in the form of bubbles. The other new materials are soluble in water and form a
solution of sodium citrate. You may filter these and find that there were no materials in the filter
paper and then evaporate the solution to see what you will find with the dry substance and
vinegar.
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DAY FOUR
Discussion on the substances formed in bag 1
Word Wall
Precipitate: solid substance that is made
when a chemical reaction occurs.
Teacher’s Notes:
It takes a day for the substance on filter paper to dry and the liquid in the evaporating dish to
evaporate. Use the suggestions from lesson 4 to do this.
Once these dry, pass the 8 samples around so students can see what has formed.
Teacher says: “Yesterday I took the contents of bag one, filtered it, and evaporated the liquid in
a dish. How does it compare to the chemicals we started with? I want you to help me investigate
what this substance might be.”
I will pass around some samples of the material so you can see it and feel it.
I have some hand lenses if you need them.
Record observations in your notebook of what you find.” Make a chart like the one on the board
so you can organize your information. (see chart below, there is also a template of this chart at
the end of this lesson)
DATA CHART 2 (record in notebooks)
Observing Substances from Bag One
Physical Properties
Observed
Substances left on
filter paper
NOTE: What to look for
Substance left in
evaporating dish
NOTE: What to look for
I think the substance is...
white substance; looks like talc
crystals that look like salt crystals
Teacher’s Notes:
Allow time for students to record their observations. They will probably say that the white
substance looks like talc and the crystals appear to be salt. Have them write why they think this
is in their charts. Check and see that students have their observations recorded in their charts.
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TESTING CHALK WITH VINEGAR (Have some chalk available and scrape off powder
with a pencil or a ruler)
Teacher says: “I see that you have enough information to help me solve my problem. First I
would like to show you something, Here is a small piece of chalk. I am going to put some drops
of vinegar on it. Tell me what you notice.” (prepare six samples so all students can see). Bubbles
and fizzing. “Now I am going to take a sample of the substance left on the filter paper and also
put vinegar in it. What do you think is going to happen?” It will make bubbles, too. Pass
around and put two or three drops of vinegar on their sample. Let students observe. “So what
could the substance that is in the filter be?” Chalk “Please record this in your chart.”
“Now I definitely think you are ready for the next part. I would like for everyone to have the
charts ready to start making some claims and evidence.”
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DAY FIVE: MAKING MEANING CONFERENCE (Teacher directed)
1) Making a class data chart: Get the overhead transparencies of the charts students should have in their
notebooks. Begin having them share what they found and filling in the information.
2) Looking for patterns from the class data chart.
Teacher guides students to analyze the chart by making claims supported by the evidence.
Teacher can say:
What claim can we make about the substances left on the filter paper?
What evidence did we have that bag 2 was a solution?
What claim can you make about bags 1 and 3 in relation to carbon dioxide?
What is the relationship between the heat, bubbling and fizzing and a chemical reaction?
How do you know if a new product is formed from a chemical reaction?
Model a T-chart inputting claims and evidence. See sample below. Teacher will guide students in writing
CLAIMS AND EVIDENCES based on the data chart. As they share information, assistance will be given
to students in making associations with the claims and evidence.
Examples
CLAIM
EVIDENCE
1. A chemical reaction occurred when we mixed
the citric acid with the calcium chloride
because there was some fizzing, bubbling, and change in
temperatures. Also the bag inflated and it changed color.
2. A different chemical compound
formed when mixing calcium chloride and
baking soda
because when we saw a different substance left on the
filter I saw something that looked like a salt crystal.
Teacher decides to list as many claims and evidence needed for students to understand the process. Once
finished teacher says: “Based on our claims and evidence let’s REVISIT THE GUIDING QUESTIONS and
discuss the possible answers using the evidence.” Teacher then goes over the guiding questions and checks to
see that students are able to answer them correctly.
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CLAIMS AND EVIDENCE (record in notebook
Teacher says,
“You are now going to write your own claims and evidence statements. I want you to look at the
GUIDING questions and write a claim based on the evidence that answers these questions. Revisit
the class data chart in order to write your claims. Record them in your notebook.” Teacher will see
students individually as they write their claims and evidence based on the guiding questions.
1) What causes a chemical reaction ?
2) How do we know if a chemical reaction has taken place?
3) How can we prove that a new substance has formed?
Example sentence st ructures:
I claim that ___________________I claim this because __________________.
I know that__________________. I know this because _________.
Share and discuss claims and evidence with the class .
Check and provide feedback.
RECOMMENDATION: Have students read page 23 - “What a Reaction” in their Science Stories.
CONCLUSION (record in notebooks)
CONCLSUION:
Students are asked to revisit their prediction. They are asked to write a statement that states
whether the evidence from their charts supported their prediction or not. They are to explain why,
with clear explanations regarding how the evidence supported or didn’t support their prediction.
Check and provide feedback
REFLECTION: (record in notebooks)
Students will revisit the “Big Idea”;
 They will write a new question/problem to start a new experiment based on the topic
covered.
 Students write their own definition of what a chemical reaction is.
 Students complete the following sentence: “What surprised me the most about this
investigation was……………

Check and provide feedback
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Note: Many students may come up with a new question wondering what would happen
if all three chemicals were mixed together with water. When all three materials are mixed
together and then water is added, something very interesting happens. The mixture
fizzes and turns clear, as in the reaction of citric acid and baking soda. Very slowly the
mixture will turn milky white as a solid precipitates from the reaction. The precipitate
forms a crust on the surface, but cannot be easily crushed into a powder. This precipitate
is calcium citrate, a material that does not have an everyday application.
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ACHIEVED
CURRICULUM
PROFICENCY FEEDBACK:
This guide is:
 to be posted on the board/butcher paper so students know what is expected in
their notebooks
 to be an evaluation tool for teachers as students work in their notebooks.
 to be converted into questions as a student self assessment piece
PROFICIENCY FEEDBACK GUIDE
Mixtures and Solutions
LE5
S
T
Focus Question:
 One question written clearly
 Related to the scenario
Prediction
 One sentence
 Uses “because”
Data
2 Charts
 Chart 1 shows observations of reactions
 Chart 2 shows detailed observations of
filter and evaporating dish
 Complete and accurate
 Labeled with titles
Claims & Evidence
 3 complete sentences showing
understanding of guided questions.
Conclusion
 Accurately shows if prediction
was supported or not and explains
why
Reflection:
 Writes one question for further
investigation
 Writes own definition of what is a chemical
reaction.
 Completes sentence starter.
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ENGAGING SCENARIO
“From Lesson 4 we now know that mixtures can be
separated, even salt water solutions.
We were able to solve the problem, thanks to you. But I have
another challenge for you. I have 3 chemicals (show the
containers) When two of the three are mixed together with
water they form a solution. But I do not know which ones to
mix. I also know that when two of these are mixed a
chemical reaction occurs. I need to know which two
produce this reaction. The product or result I get is CO2, a
chemical compound you are familiar with. This is totally
different from the original substances, which I cannot get
back now. The chemicals I have are: Baking soda (NaH
CO3), Calcium Chloride (CaCl) and citric acid (C6 H8 O7).
How can I solve my problem?”
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LAB INSTRUCTIONS
1. Put one spoonful of each of the chemicals baking soda (NaH CO3 ) + calcium
chloride (Ca Cl ) in ziplock bag #1.
2. Fill the syringe with the 25 ml of water that you can get from the materials
station..
3. Close the zip bag, but leave an opening big enough to insert, or put in, the
syringe.
4. PRESS ALL THE AIR OUT OF THE BAG.
5. QUICKLY add the 25 ml of water to the mixture, remove syringe and
close the bag immediately.
6. Gently shake the bag and record what you observe.
7. DO NOT OPEN THE BAG AT ANY TIME.
8. Carefully put the bag aside and begin testing the next pair of chemicals.
9. Repeat the same instructions for bags #2 [calcium chloride (Ca Cl) + citric
acid (C6 H8 O7)] and #3 [ (baking soda (NaH CO3 )+ citric acid (C6 H8 O7)].
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CHART ONE - OBSERVING REACTIONS
Substances and Chemical
Formulas
1
baking soda
calcium chloride
+ water
NaH CO3
Ca Cl
H2O
2
calcium chloride
citric acid
+ water
Ca Cl
C6 H8 O7
H2O
3
baking soda
citric acid
+ water
NaH CO3
C6 H8 O7
H2O
Observations
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Part II
Observing Substances from Bag One
Substances
Physical Properties
Observed
I think the
substance is….
Substances left on
filter paper
Substances left in
evaporating dish
TESLA Mixtures and Solutions
DRAFT 07/01/08 – Option 1
Lesson 5 - Chemical Reactions, Reaction Products, and Reaction in a Zip Bag
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