Chemistry Mystery: Solve A Crime With Chemistry!

Today you are at the scene of a chemistry crime!

 

The Scenario:

Your lab has been broken into, and 6 prominent local chemists have been identified as suspects.  Each have traces of a different substance on their clothing.

Some unidentified powder has been found in your lab – and you need to match it to one of the suspects so the police know who to focus on.

DownloadChemistry Mystery Lab Sheet

 

The Suspects:

Here are the suspects, and the substance found on their clothing:

Dr. Sweets Sugar
Dr. Baker Baking Soda
Dr. White Baking Powder
Dr. Jackson Cornstarch
Dr. Morgan Cream of tartar
Dr. Mastiff Borax or powdered laundry detergent

 

The Plan:

To prepare your analysis, you’ll first need to gather your materials.  You’ll need samples of each of the above substances, plus the following liquids for testing:

  • Iodine solution (add 1 teaspoon tincture of iodine to ¼ cup water)
  • White vinegar
  • Tap water
  • Red cabbage juice (instructions below)

How to make red cabbage juice:

  1. Tear 2 red cabbage leaves into small pieces, and place in a zip lock bag with 1 cup of warm water.  Remove as much air from the bag as possible before sealing.
  2. Squeeze the leaves through the bag until the water turns medium to dark blue.
  3. Pour the liquid from the bag into a cup.

 

Chemistry Testing Lab:

Once you have your materials together, set up your lab station.  You’ll need to complete the table below, so you know how the substances you are evaluating react to each of the testing liquids:

Iodine Vinegar Water Red Cabbage
Sugar
Baking Soda
Baking Powder
Cornstarch
Cream of tartar
Borax or powdered laundry detergent
  1. Put 1 teaspoon of the first liquid into a small cup or container, and add ¼ teaspoon of the first powder.
  2. If nothing happens, stir gently with a popsicle stick and evaluate again.
  3. Write down the reaction you see, or “no change”.
  4. Rinse and dry your container, and repeat with the next combination.

Solving The Crime:

Once your reference table is completed, the detective will give you a sample of the powder found at the scene.  Test it with your liquids – and let the detective know who to arrest!

 


Teacher Information:

–>DownloadChemistry Mystery Lab Sheet

 

Complete materials list:

  • Sugar
  • Baking Soda
  • Baking Powder
  • Cornstarch
  • Cream of tartar
  • Borax or powdered laundry detergent
  • Tincture of iodine
  • White vinegar
  • Red cabbage juice (instructions to prepare above)
  • Small cups or containers
  • 1 teaspoon and ¼ teaspoon measuring spoons
  • Popsicle sticks

 

Suspect Identification:

You can select your choice of powder for the suspect testing.

 

Expected results:

Iodine Vinegar Water Red Cabbage
Sugar Stays orange No change No change Blue
Baking Soda Stays orange Bubbling that ends quickly No change Blue
Baking Powder Bubbling, purple Bubbling Bubbling Pinkish-purple, then fades to blue, bubbles
Cornstarch Purple No change No change Blue
Cream of tartar Stays orange No change No change Pink
Borax or powdered laundry detergent Yellowish Sudsy No change Green