Objective:
Campers will learn about how the air we exhale can cause problems in
enclosed spaces, what NASA has done about it, and how we use the technology
on Earth.
Materials:
4 medium sized flasks or bottles with narrow openings
clay to seal the flasks
flexible straws
carbon dioxide source—student's exhaled air
calcium hydroxide
lime water
Bad Breath Apparatus Diagram
Assemble apparatus as shown in the diagram for younger students; older
students should do the apparatus assembly themselves using a ledger sized
poster of the Bad Breath Apparatus Diagram. When assembling the apparatus,
you will want to make a short slit (1/4") in the end of one of the straws
at each joint so that one will fit inside the other. Note that the straw to
the right in each flask should be about an inch shorter than the other.
Copy the Observation Sheet.
Procedure:
- Discuss how we exhale carbon dioxide and discuss the need to rid the
small quarters of the space shuttle of it to prevent the astronauts from
suffocating.
- Explain that lime water is an indicator of carbon dioxide gas. In the
presence of lime water, carbon dioxide produces a fine powdery precipitate
that makes the solution appear milky white and Calcium hydroxide reacts
with CO2, binding it, thus removing it from the air.
- Have groups of 3-5 campers set up the apparatus in the diagram. Place
lime water in each of the 4 flasks.
- Add calcium hydroxide to the 2nd, 3rd and 4th beakers. As you seal each
flask again, you should check the seal on each by blowing into the left
straw in flask #1. You should see bubbles in each flask as you blow. If you
do not, there is a weak section.
- Have a camper exhale into the straw continuously for 10 minutes.
- Campers should observe and record the color of the liquid in each of
the 4 flasks during that 10 minute period, noting the changes that they see
after each minute.
- Discuss how NASA uses similar technology to clean the air in the
shuttle and how we use it to purify air for toll booth attendants.
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