Name:__________________________Pd:_____________Date:______________
Law of Conservation of Mass Investigation Activity
In this activity you are going to use two mixtures, one will be water and salt, and the other will be
sodium carbonate solution and copper(II) chloride solution, to better understand the Law of
Conservation of Mass.
Introduction:
A: What is the Law of Conservation of Mass?
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B: Tell me what observations can be made when small amounts of salt and warm water mix? What
happens to the salt? What happens to the water?
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C: What do you think will happen when we mix the sodium carbonate and the copper(II) chloride
solutions? What will happen to the mass?
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Hypothesis:
What will happen to the mass of the solutions when mixed? (If, then, because)
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Name:__________________________Pd:_____________Date:______________
Materials:
The materials in this lab are
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Procedure:
Step 1: Pour a small amount of sodium carbonate into a glass vial, slightly less than half full. Seal the vial
with a cap and weigh the vial. Record the mass below.
Step 2: Pour a small amount of copper(II) chloride into a glass vial, slightly less than half full. Seal the
vial with a cap and weigh the vial. Record the mass below.
Step 3: Remove both caps from the two vials. Pour the clear sodium carbonate fluid into the vial with
the blue fluid, the copper(II) chloride. Seal the vial and record the mass below.
Step 4: Pour a small amount of water into a glass vial (no more than half full), put a cap on it. Weigh it
on the scale and record the mass below.
Step 5: Place a small amount of salt into a glass vial using a scoopula, and put a cap on it. Weigh it on
the scale and record the mass below.
Step 6: Take the caps off of the water and salt vials and pour all the water from the small glass vial into
the glass vial with salt in it. Replace the cap on the vial with both the water and salt in it.
Step 7: Shake the vial vigorously until the salt has dissolved into the water. Measure the mass of the vial
with the mixture in it. Record the mass below.
Step 8: Record your observations of the salt and water mixture in the observations section.
Step 9: Go back to the vial of blue solution. Record what you see in your observations.
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Name:__________________________Pd:_____________Date:______________
Results:
Quantitative Observations
grams
Description of vial contents
Mass of a glass vial (grams)
Mass of sodium carbonate in vial (grams)
Mass of copper(II) chloride in vial (grams)
Mass of the mixture of the two (grams)
Mass of the water in vial (grams)
Mass of the salt in vial (grams)
Mass of the mixture of the two (grams)
Observations:
Write down what you observe happening with the salt and the water, and talk about what happened
with the mass of the solution as well as what the solution looked like at the end of the experiment. (no
opinions here, just state facts you saw, and numbers you measured):
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Write down what you observe happening with the sodium carbonate and the copper(II) chlroide, and
talk about what happened with the mass of the solution as well as what the solution looked like at the
end of the experiment. (no opinions here, just state facts you saw, and numbers you measured):
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Name:__________________________Pd:_____________Date:______________
Analysis:
What do you think happened to the salt? Explain:
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What do you think is that cloudy material in the blue mixture? Was it there right away at the beginning
when you first mixed the two chemicals? What do you think is happening in the vial?
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Does the experiment follow the Law of Conservation of Mass? Explain:
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Name:__________________________Pd:_____________Date:______________
Conclusion CER:
Claim
(restate your hypothesis in this box)
Evidence
(restate the evidence you collected in a concise few sentences. This should
include your qualitative and quantitative evidence)
Reason
(your justification for your claim/hypothesis)
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Name:__________________________Pd:_____________Date:______________
Writing Scientific Arguments
C.E.R’s
The scientific curriculum at Smyrna High School will often include written responses known as
C.E.R’s, this stands for Claim, Evidence, and Reasoning. These responses will be structured
answers/arguments to scientific questions. The following is a guide to help the process of
building a well written scientific argument or C.E.R.
Claim
The claim is a statement about the results of an investigation.
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A complete one sentence answer to the question you’re investigating
It answers, “What can you conclude?”
It should describe the relationship between the dependent variable and independent
variable (if applicable)
This statement should not include any evidence or reasoning.
Evidence
The scientific data used to support the claim.
Evidence must be:
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Sufficient- Use enough evidence to support the claim
Appropriate- Use data that supports your claim. Leave out information that does not
support the claim.
Qualitative (data gathered from observations or your senses), or Quantitative
(numerical data), or a combination of both.
Reasoning
Statements that tie together the claim and the evidence
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Shows how and why the data count as evidence to support the claim
Provides the justification for why this evidence is important to this claim
Includes one or more scientific principles (content relevant to what is being covered or
what was covered in class) that are important to the claim and evidence
Your reasoning should not include an explanation of the scientific principle itself.
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