27. FRED, WE NEED A TREE IN HERE!

CABIN ATMOSPHERE AND CARBON DIOXIDE REMOVAL
SUBJECT: Science
GRADE: 7,8,9
GROUP SIZE: Large
TIME: 45 minutes
TYPE OF ACTIVITY: Teacher Demonstration
TEACHING STRATEGY: Guided Discovery
CONCEPTS: Solubility of Gasses Air Purification
SKILLS: Observation Inference Reading for Data

Objective: To understand that CO₂ can be removed from exhaled air.

apparatus setup diagram

Materials: Three 250ml flasks or bottles; glass tubing; rubber tubing; three two – hole stoppers to fit containers; lime water – Ca(OH)₂
Procedure:

Assemble the glass tubing, rubber Stoppers, rubber tubing as shown in the diagram.

SAFETY NOTE: NEVER ATTEMPT TO PUT GLASS TUBING THROUGH A STOPPER WITH BARE HANDS. PUT GLYCERIN ON THE TUBING FIRST WHICH WILL ALLOW IT TO SLIP INTO THE STOPPER EASILY.

Add lime water to each of the containers so that end of the long glass tubing in each will be covered. Be sure the short tube is clear of the liquid. Stopper bottles and have a student blow through one end of rubber tubing. The exhaled air will pass from one container to the next until it is expelled from the far end of the apparatus. Observe the color changes in containers. How do you account for the changes in the contents of each flask? Are all the containers the same now? What may have happened to cause them to be the way they are now?
Discuss with the students whether or not this system for the removal of Carbon Dioxide is a practical one for use on a spacecraft.
Extensions: Have the students explore NASA data to see how Carbon Dioxide is removed (scrubbed) from the air in a space vehicle. Explore the question: Why don’t we have to remove CO₂ from the atmosphere on Earth? Relate the removal of Carbon Dioxide to the process of photosynthesis in green plants. Plants have also been used on board space vehicles for the production of Oxygen.

Adapted from educational materials available from NASA Kennedy Space Center Teacher Resource Room