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Chemical Magic    Mystery 5

Mystery 5 image

In this Mystery, students investigate and model how gases cause explosions. In the activity, students experiment by combining baking soda and vinegar inside a sealed bag and observe how the gas bubbles produced cause the bag to inflate–and sometimes pop!

Why do some things explode?

Beginning Exploration (1 of 8)
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Beginning Exploration (2 of 8)

DISCUSS:

What makes these things explode? What’s going on?

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Beginning Exploration (3 of 8)
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Beginning Exploration (4 of 8)

DISCUSS:

Why do you think the containers were shattering?

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Beginning Activity Prep
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Activity Prep

This mystery includes two activities: a baking soda explosion in a plastic bag (carefully designed to avoid a mess), and a hands-on model that helps students understand why the plastic bag explodes.

Students will work in pairs for the first activity, and in groups of four for the second activity. Students working alone will need a partner for the first activity, and a few friends to help with the second activity.

Step 1: Gather supplies

To prepare supplies, you’ll need:

  • a ¼-cup measure
  • a plastic cup or container to hold the vinegar for each table of students (see Step 2)
  • a plastic or paper cup to hold the baking soda for each table of students (see Step 2)
  • paper towels for cleanup

Each student will need:

  • a ziplock snack bag, like this. (Use snack bags rather than sandwich bags. Sandwich bags need more vinegar and baking soda, and the resulting explosion is likely to overflow the plastic plate.)
  • a small paper cup (3-ounce bathroom cups, also known as Dixie cups, work well)
  • scissors

Each pair of students will need:

  • a plastic plate like these, or a large, sturdy paper plate (Note: You can wash and reuse plastic plates for future activities)
  • at least ¼ cup of vinegar (1 quart for a class of 32)
  • at least ¼ cup of baking soda (about 1½ pounds for a class of 32)
  • 2 plastic spoons, each holding about 1 teaspoon (students will use one for measuring vinegar, and the other for measuring baking soda)

Step 2: Print worksheets and prepare supplies

Print out:

For each table of four students (two pairs), prepare:

  • a container holding ½ cup of vinegar
  • a container holding ½ cup of baking soda
Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Exploration (5 of 8)
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Beginning Exploration (6 of 8)

DISCUSS:

On the back of your worksheet, draw a picture using a particle model to explain why the bag exploded. (Or you can label or add to the picture you drew earlier.)

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Beginning Exploration (7 of 8)
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Activity: Bag of Bubbles
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Beginning Exploration (8 of 8)
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Beginning Complete!

You've completed the Exploration & Activity!

If you have more time, view the assessment, reading and extension activity in the optional extras.

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Optional Extras

Below are ideas for extending this topic beyond the activity & exploration which you just completed.
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Readings

These readings will get students thinking about the gases that surround us, the Earth’s atmosphere. Free with registration on Newsela Elementary, they are in English or Spanish and can be adjusted for reading level. Writing prompts and quizzes are available for each reading.

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Activity: Inflate a balloon

Follow these instructions, to fill a balloon with carbon dioxide, the same gas that filled your plastic bag. Try the experiment, and then:

  • Draw a picture that shows what makes the balloon inflate.
  • Predict what will happen if you pinch the neck of the inflated balloon, take it off the bottle, then let it go. Draw a picture that shows what’s happens when you do that — and why it happens.

If you have time, experiment to figure out what ratio of baking soda to vinegar produces the most gas (and the biggest balloon).

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Discussion: Bread bubbles (part 1)

Look at the holes in this slice of banana bread. Each hole was made by a bubble that formed while the bread was baking. Those bubbles made the bread rise. bananabread

Go to the next slide to discuss where those bubbles came from.

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Discussion: Bread bubbles (part 2)

Here are the ingredients used to make banana bread:

  • vinegar
  • milk
  • butter
  • sugar
  • bananas
  • flour
  • baking soda
  • walnuts
  • eggs
  • Discuss:

    • Why do you think bubbles formed in the batter?
    • What do you think would happen if you left out the vinegar?

    See previous slide for a view of the holes in banana bread. See next slide for more about the bubbles in bread.

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    Discussion: Bread bubbles (part 3)

    Any bread or cake that rises as it bakes has bubbles in the batter. Take a look at some bread recipes. Can you figure out which ingredients make bubbles in each recipe?

    If you need help, check out this extensive discussion of leavening agents. (A leavening agent is a substance that produces gas to make bubbles in a batter.)

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