Carbon Dioxide Sources and Sinks Activity - Student Page

Student Directions

Launch: With a partner, discuss and write down everything you know about carbon dioxide. Contribute to a class list. As you investigate over the next few days, think about what are carbon dioxide sources and sinks and how carbon dioxide contributes to Earth’s climate.

Investigate: Carbon dioxide (CO2) provides the bubble in your soda pop and the “rise” in your baked goods. But it is also a very significant greenhouse gas. CO2 is important in maintaining the Earth’s average temperature of about 15°C (59°F). The CO2 traps infrared energy emitted from the Earth’s surface and warms the atmosphere. Currently, the amount of carbon dioxide and other greenhouses gases in the atmosphere is increasing causing global climate change. In this activity you will investigate some of the ways that carbon dioxide gets into and out of the atmosphere.

  • Where does CO2 come from?
  • How does CO2 get into the atmosphere?
  • What are ways that CO2 is taken out of the atmosphere?

Part 1: Detecting CO2

Create a T-chart in your science notebook as follows:

CO2Source CO2Sink
   

Materials (for each group of 3):

  • Safety goggles
  • ~12cm of masking tape (to make labels)
  • Sharpie
  • 6 test tubes
  • Test tube stopper with tubing
  • Test tube rack
  • A small beaker of BTB solution
  • A small beaker of vinegar
  • A small sample of baking soda
  • 1 2.5cm x 2.5cm square of foil
  • 1 15cm x 15cm square of foil
  • 3 cotton balls
  • 1 straw

Directions:

  1. With your group of 3, identify who will play each role. You will have the opportunity to have all three roles during this investigation.

    1. Equipment manager-collect all materials for the investigation; manage equipment use and safety.

    2. Facilitator and data collector-read protocol to your group; record observations and data.

    3. Technician-conduct investigation.

  2. With small pieces of masking tape, label the test tubes A thru E (one test tube will be unlabeled).

  3. Put test tubes A, B, and the unlabeled test tube in a test tube rack.

  4. Fill test tubes A and B approximately 1/3 full with the BTB solution and place in the rack. Test tube A will be used as a control.

  5. Fill the unlabeled test tube approximately 1/4 full of vinegar.

  6. Using the foil, make a small “boat” for the baking soda. Fill 1/2 full of baking soda. (hint: The ‘boat’ should be small enough to easily fit into the test tube and float on the vinegar).

  7. Carefully slide the foil boat inside the unlabeled vinegar test tube (hint: tilt the test tube at an angle and carefully slide the boat in, being careful not to allow the baking soda and vinegar to make contact).

  8. Plug the test tube with the stopper and tubing.

  9. Place the free end of the tubing in test tube B, making sure the end of the tubing reaches the bottom of the test tube.

    1. Place a cotton ball into the neck of the test tube B.

  10. Mix the vinegar and baking soda together by GENTLY swirling the unlabeled test tube from side-to-side Do NOT shake the test tube or turn it upside down.

Answer the following questions in your notebook.

  • What did you observe when the bubbles moved into the BTB solution in test tube B? Record your observations, adding both descriptions and sketches.

  • How can you use BTB an indicator for the presence of CO2?

Part 2: CO2 Sources and Sinks - Animals and Plants

Switch roles in your group.

  1. Fill test tube C approximately 1/3 full of BTB.

    1. Place a straw in the test tube.

    2. Place a cotton ball in the test tube opening.

  2. Gently blow in the straw.

Answer the following questions in your notebook.

  • What did you observe when you blew in test tube C? Record your observations, adding both descriptions and sketches.

  • How do the results of this investigation compare to Part 1?

  • Are animals a source of CO2? Describe how you know.

Switch roles in your group.

  1. Fill test tube D approximately 1/3 full of BTB.

    1. Place a sprig of Elodea into the test tube (Hint: Use a pencil to push it all the way to the bottom of the tube).

    2. Wrap the tube in foil so that no light can get in.

  2. Place in test tube rack and leave for at least 24 hours.

Next day

  1. Unwrap the foil. Record your observations in your notebook, adding both descriptions and sketches.

  2. Using the now-unwrapped test tube D with Elodea, leave in the light and observe what happens.

Answer the following questions in your notebook.

  • What did you observe when you first unwrapped the foil from test tube D? Record your observations, adding both descriptions and sketches.

  • What did you observe when you put the unwrapped test tube in the light? Be descriptive.

  • Are plants a source of CO2? Explain your thinking based on your investigations.

Part 3: Fossil Fuel Sources of CO2

You will watch a class demonstration provided by your teacher. Use your notebook to record observations, notes, and questions.

  1. Using test tube E, collect a sample of BTB from your teacher. You will compare all of your test tube samples.

Answer the following questions in your notebook.

  • What was in the balloon?

  • What did you observe when your teacher released the balloon’s contents into the beaker? Use both a description and sketches.

  • Compare the colors in all of the test tubes, A-E. Are they different? If so, why? Explain your reasoning.

  • Draw a picture in your science notebook showing how CO2 enters and gets taken out of the atmosphere. Use the ideas from your investigations and the demonstration. With your group, create a poster that represents your ideas of CO2 sources and sinks. Hang your poster on the classroom wall. Visit other group’s posters and add to your notebook any ideas that you gain.