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Chemical Magic    Mystery 1

Mystery 1 image

In this Mystery, students meet the alchemists, a historic group that used “potions” to try to transform materials. In the activity, students test what substances change the appearance of copper.

LESSON REVISED 1/11/18. If you prepped before then, use the previous version.

Beginning Exploration (1 of 15)
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Beginning Exploration (2 of 15)

DISCUSS (1 of 2):

Do you think there could really be a potion that does something amazing or valuable? (Do you think there are really liquids or mixtures that can transform things?) Why or why not?

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Beginning Exploration (3 of 15)

DISCUSS (2 of 2):

If you could make a potion, what would you want it to do?

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Beginning Exploration (4 of 15)
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Beginning Exploration (5 of 15)

GET A SUPPLY:

Everyone get 1 dull, brown penny. Then:

DISCUSS:

Suppose you wanted to make this dull brown penny bright and shiny. Can you think of any liquids in your house that might do that?

Why do you think those liquids might work?

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Beginning Activity Prep
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Activity Prep

In this activity, your students will test liquids to see which ones can clean the tarnish off a penny. Then, when one penny changes from dark and dirty to bright and shiny, they’ll have a chance to think about where the tarnish went. In a class, this activity works best when students work together in groups of four, but students can also work alone.

Two quick notes:

  • Review the instructions in Step 4 before you begin. In the next Mystery, you’ll need to reuse some of the materials from this Mystery so students can copperplate a steel nail.
  • If you’re working with a small group or solo student, you can make 1 cup of each solution, rather than 2 (see Step 3). When you set up your stations, just cut the “recipes” in half.

Step 1: Plan ahead

You’ll need old, tarnished pennies for this activity. For best results, use pennies dating from BEFORE 1982, when they were made from 95% copper. (Pennies made after 1982 are copper-plated zinc, which won’t work for this activity; in 1982, both varieties were made.)

If you’re working with a class, we suggest asking students to bring in pennies made before 1982. You can also buy penny rolls at the bank. We bought $3 worth, sorted out the pre-1982 pennies, and had exactly 40 to work with.

Step 2: Get your supplies

You'll need:

  • pre-1982 tarnished pennies (You’ll need at least one for each student, plus a few extras—that’s about 40 pennies for a class of 32. If you have a small group or solo student, you’ll need at least 20 pennies.)
  • measuring spoons and cups
  • 4 plastic food-storage containers that hold just over 3 cups each, like these. (You’ll need one container for each test station.)
  • tape for labeling containers
  • 4 cups of water
  • 2 tablespoons of liquid detergent
  • 4 cups of white vinegar (You’ll use vinegar again in Chemistry Mysteries 3, 4, and 5, so we suggest getting a gallon.)
  • 1 cup of salt (You’ll use another cup of salt in Chemistry Mystery 3, so we suggest getting a 26-ounce container.)
  • steel nails (Note that it’s important that you get steel nails like these—NOT stainless-steel nails, and NOT galvanized nails. We recommend asking at your local hardware store. If you can’t find steel nails, you can substitute steel washers as long as they are not galvanized and not stainless steel. You can also substitute jumbo paper clips.)
  • optional: an orange and a brown colored pencil for each group of students (For coloring dull and shiny pennies on worksheets.)

Step 3: Prepare for class

Print out these materials:

Prepare these four testing liquids in your labeled containers and set up separate test stations:

  • Station 1: Mix 2 tablespoons liquid detergent with 2 cups water in the Soapy Water container.
  • Station 2: Pour 2 cups of vinegar into the Vinegar container.
  • Station 3: Mix 6 tablespoons salt with 2 cups vinegar in the Salty Vinegar container. (It won't all dissolve, but add it anyway.)
  • Station 4: Mix 6 tablespoons salt with 2 cups water in the Salty Water container. (It won't all dissolve, but add it anyway.)

Step 4: After class—including preparation for the next Mystery

  • Save student work: Students will need their completed “Alchemist’s Potion” worksheets for the next Mystery. Make sure they’re stored somewhere safe.

  • Save the pennies in the Salty Vinegar solution: At the end of this Mystery, you’ll dump all the pennies into the Salty Vinegar to soak overnight. (If you made just 1 cup of salty vinegar, dump all 20 pennies into it.)

  • Add a nail: After students have left class, we recommend that you put a nail into the Salty Vinegar solution with the pennies—but don’t tell your students you’re doing it. You’ll find out why in the next Mystery, when your students will discover that the solution the pennies soaked in can change steel nail in a surprising way.

Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Exploration (6 of 15)
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Beginning Exploration (7 of 15)

DISCUSS:

Do you think oxygen turns the penny dark brown all the way through, or just on the surface? How could you figure it out?

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Beginning Exploration (8 of 15)
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Beginning Exploration (9 of 15)

DISCUSS:

How could you figure out which of these three ideas is true? Wind Map

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Beginning Exploration (10 of 15)
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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Beginning Activity: Test Like An Alchemist
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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

Learn more about the alchemists and how their work laid the foundation for the science of chemistry with these readings:

  • “Can You Turn Iron into Gold?” from Wonderopolis, a website dedicated to curiosity and imagination, created by the National Center for Families Learning.

  • From Alchemy to Chemistry from Newsela, a free service for teachers. (Reading includes comprehension questions and can be adjusted for reading level.)

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Activity: Zinc Inside

Try this experiment with a US penny made after 1982. These coins have a center made of zinc, a silvery metal that reacts with vinegar and salt.

  • Rub the penny's edge with sandpaper until you see silvery zinc. Do the same on the other side of the penny.
  • Mix 1-½ tablespoons salt and ½ cup vinegar in a clear container.
  • Drop in the penny and watch. What do you notice? Leave the penny in the mixture overnight.

In our experiment, the center of the penny dissolved leaving behind a thin shell of copper. What happened in your experiment?

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Video: Rusty Steel in Vinegar

Watch this time-lapse video, then discuss:

  • What do you think happened to the rust that was on the steel?
  • Do you have any ideas about why putting oil on the steel might keep it from rusting again?

To find out more about what happens to rust and tarnish in vinegar, watch the next Mystery, "Could you transform something worthless into gold?"

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