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Chemical Magic    Mystery 2

Mystery 2 image

In this Mystery, students investigate the alchemists’ claim of transforming ordinary metals into gold. In the activity, students coat a steel nail with copper and develop a particle model to explain what they observe.

THIS LESSON WAS REVISED ON JANUARY 11, 2018. If you've prepped prior to that date, we suggest using the previous version.

Could you transform something worthless into gold?

Beginning Activity Prep
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The King's Sword

To do this activity, you must have completed the activity in Mystery 1.

In this activity, students will add copper to a steel nail using the copper-rich solution made in Mystery 1. Students will work together in teams of four. Students working alone will need a helper for some steps, but should be able to do most of the activity on their own.

Step 1: Plan ahead

At the end of the last Mystery, you put all the pennies in a vinegar-and-salt solution, added a steel nail when students were gone, and then left the solution overnight. To prepare for this activity, check on that solution before class and look at the nail you put in. All or part of the nail should now be covered by a layer of copper.

Take the nail out of the solution, rinse it off, and set it aside to show your students during the last video. Save the penny-filled solution for students to use in this activity.

Students will also need the “Alchemist’s Potion, Part 1” worksheets that they completed in Mystery 1.

Step 2: Print out materials and get supplies

For the classroom, you’ll need:

  • the penny-filled salt-and-vinegar liquid from Mystery 1
  • the “Alchemist’s Potion, Part 1” worksheets students completed in Mystery 1
  • 4 plastic spoons (for students to scoop up the solution and pennies)
  • a plastic box or bin, plus binder clips or clothespins (to keep bags for students who need to leave their experiments overnight)
  • paper towels (for cleanup)

Each student will need:

Each group of four students will need:

  • a plastic or paper plate
  • 2 stick-on labels (or one label and a strip of masking tape)
  • a ziplock bag (either snack-size or sandwich-size will work)
  • a steel nail (As noted in Mystery 1 Activity Prep, it’s important to use steel nails like these—NOT stainless-steel nails, and NOT galvanized nails. 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.)
  • a 3-ounce paper cup (we use bathroom cups, also known as Dixie cups)
  • orange, brown, and grey pencils, crayons, or markers for drawing and to write on labels (optional)

Step 3: Prepare for class

To distribute materials quickly and easily, we recommend you set out plates, labels, and pencils or markers for each group, and then set up three stations for student use:

  • Station 1: Pennies in the vinegar-and-salt solution along with the spoons for scooping up pennies and one Dixie cup for each group
  • Station 2: A plastic bag for each group
  • Station 3: A steel nail for each group

Step 4: After class

If conditions are just right, copper forms on the steel quickly. But in many cases, students may need to leave their experiments for a few hours or even overnight to see results.

To store students' experiments overnight, we suggest clipping the bags to the sides of a plastic box or bin, with the bags hanging over the inside of the box. This ensures that the nail remains submerged in the liquid. In the unlikely event that one of the bag leaks, the bin will catch the vinegar.

Beginning Activity: The King's Sword
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Beginning Activity: The King's Sword
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Beginning Activity: The King's Sword
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Beginning Activity: The King's Sword
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Beginning Activity: The King's Sword
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Beginning Activity: The King's Sword
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Beginning Activity: The King's Sword
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Beginning Exploration (1 of 10)
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Beginning Exploration (2 of 10)

DISCUSS (1 of 3): Can you think of any tests you could do, that would help you figure out which idea is true?

2 possibilities

Here’s an idea we had...

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Beginning Exploration (3 of 10)

DISCUSS (2 of 3):

Suppose we give you a scale, a tool that measures weight. Using a scale, is there a test you could do to figure out which idea is true?

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Beginning Exploration (4 of 10)

DISCUSS (3 of 3):

If the vinegar and salt REMOVED the dull copper, then what should we find out when we weigh the penny before and after?

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Beginning Exploration (5 of 10)
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Beginning Activity: The King's Sword
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Beginning Exploration (6 of 10)
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Beginning Exploration (7 of 10)

DISCUSS:

Why do you think the alchemist left, never to be heard from again? Was there something he didn’t want the king to figure out?

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Beginning Activity Prep
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Beginning Activity: The King's Sword
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Beginning Activity: The King's Sword
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Beginning Exploration (8 of 10)
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Beginning Exploration (9 of 10)

DISCUSS (1 of 2):

Why do you think we couldn’t we see little bits of copper in the liquid?

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Beginning Activity: The King's Sword
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Beginning Exploration (10 of 10)
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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 are free with registration on ReadWorks, a nonprofit committed to providing teachers with research-proven, Common-Core-aligned readings. All readings include comprehension questions.

The Penny Experiment tells the story of a girl who experiments with pennies and vinegar and learns about why copper changes color. (Grade 6)

The Allure of Gold discusses why people have always valued gold. (Grade 6)

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Activity: Blue-Green Pennies

Vinegar and salt can make a penny bright and shiny. Can it change the copper of a penny in other ways?

If you read “The Penny Experiment” in our list of readings, you know the answer.

To try the experiment described in the story, follow these instructions from Buggy and Buddy to find out.

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Video: Penny in Nitric Acid

You’ve watched what happens to a penny in vinegar, a weak acid. What happens if you put a penny in nitric acid, a strong acid?

This experiment is too dangerous to try in your classroom, but it’s interesting to watch. In this video, scientist Wayne Breslyn demonstrates how to do the experiment safely.

The reaction creates a brown gas called nitrogen dioxide, which is dangerous to breathe. The humming you hear in the video is the fan of a fume hood. The fume hood removes the nitrogen dioxide so no one will breathe it.

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