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The Arizona STEM Acceleration Project

Balloon Lab: Law of Conservation of Mass

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Balloon Lab: Law of Conservation of Mass

An 8th Grade STEM Lesson

Amber Caulkins

7/18/23

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Notes for Teachers

This lessons allows students to explore the Law of Conservation of Mass through a lab activity.

Students will develop a model to describe their findings after completing this lab.

List of Materials

  • Bell ringer type handout for opening discussion
  • Lab handout
  • Balloons
  • Baking Soda
  • Vinegar
  • Scale
  • Plastic spoon
  • Empty soda bottle

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Standards

Physical Science

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8.P1U1.1 Develop and use a model to demonstrate that atoms and molecules can be combined or rearranged in chemical reactions to form new compounds with the total number of each type of atom conserved.

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ELA Standard

8.SL.5 Include multimedia components and visual displays in presentations to clarify claims and findings and emphasize salient points.

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Mathematical Practices

5. Use appropriate tools strategically.

Science and Engineering Practices

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  • plan and carry out investigations
  • develop and use models
  • engage in argument from evidence

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Objective(s):

  • Describe the Law of Conservation of Mass
  • Identify the reactants and products in your lab analysis
  • Develop a model that demonstrates the Law of Conservation of Mass

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Intro/Driving Question/Opening

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What happens to matter when a chemical reaction occurs?

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Share your response with your table, beginning with seat 1.

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What happens to matter when a chemical reaction occurs?

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Develop a one sentence answer based on what your table discussed and one person will write your response on a white board.

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Hold Up Your White Board As The Teacher Reads Aloud The Responses.

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As a class we will determine the best answer and add it to our notebooks.

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LAB

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Question we are exploring:

In a closed system, will the mass remain the same after a chemical reaction takes place?

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Lab Directions

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1. Measure 45 mL of vinegar.

2. Add the vinegar to your bottle.

3. Stretch your balloon out several times.

4. Add 3 level teaspoons of baking soda to your balloon.

5. Carefully place the mouth of the balloon over the opening of the bottle to make tight seal. The balloon will hang to the side of the flask. The baking soda should not be mixed with the vinegar at this stage. Record observations on your lab handout.

6. Find the mass of the closed system (flask, vinegar, balloon, and baking soda) using your scale. Record the mass in the data table.

7. While the balloon is still attached to the flash, lift the balloon so that the baking soda falls into flask and combines with the vinegar.

8. Find the mass of the closed system again (flask, vinegar, balloon, and baking soda). Record the mass in the data table. Record all observations.

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Part 2:

1. Find the mass once the chemical reaction has occurred. Keep the balloon attached.

2. Record the data on your data table.

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Part 3:

1. Remove the balloon and let all the gasses escape.

2. Place the deflated balloon back onto the bottle.

3. Find the mass again.

4. Record the data on your data table.

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What are the reactants? What are the products?

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Use your handout to answer the following questions:

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  1. What evidence did you observe that indicated a chemical reaction took place?
  2. After the gas was released, what happened to the mass and why?
  3. Restate the Law of Conservation of Mass in your own words. Did your results support this statement?

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Draw a model of what occurred in the lab on your whiteboard.

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We will present our whiteboards to the class and discuss our findings.

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Use the Claim-Evidence-Reasoning Table to answer the following question:

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How is the lab an example of the Law of Conservation of Mass?

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Exit Ticket

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What is the Law of Conservation of Mass in your own words?

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Agenda (60 minutes) (1-2 Class Periods)

Opening Question & Discussion 5 minutes

Class Discussion 5 minutes

Lab & Present Responses 35 minutes

Write a CER Statement 10 minutes

Exit Ticket 5 minutes

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Assessment

  • Model developed after lab
  • Assessing the CER response
  • Exit Ticket

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Differentiation

  • Students who are having a difficult time understanding the assignment will be paired with a mentor student.
  • The teacher will also work with small groups as needed.
  • Provide key vocabulary with images.
  • Provide book and video resources as needed.

Remediation

Extension/Enrichment

An extension activity could be having students research and write about other examples of Conservation of Mass.