Chemistry
HS/Science
Unit: 08 Lesson: 01
The Mathematics of the Carbon Dioxide Scrubber
History
"Okay, Houston, we've had a problem here," said astronaut James A. Lovell to Houston
Mission Control at 55:55:35 after liftoff of the Apollo 13 mission on April 13, 1970. Apollo 13,
the third lunar landing mission, had started off with very few surprises. Mission Control in
Houston broadcast that the spaceship was in “real good shape” and that the crew on the
ground in Houston was “bored to tears.” Nobody mentioned boredom after that message.
At 55:46 into the flight, the crew had just completed a TV segment in which they
demonstrated the effects of weightlessness on activities in their living quarters. They
concluded with “this is the crew of Apollo 13 wishing everybody there a nice evening…” Nine minutes later, oxygen tank
#2 blew up causing oxygen tank #1 to leak into space. 200,000 miles from Earth, the Apollo 13 Command Module (CM)
had also lost two of its three fuel cells. It was crippled.
Mission Control decided to move the crew from the CM to the Lunar Module (LM) in order to return home. Although fuel in
the LM had to be conserved and water and food had to be rationed, a major concern was removal or “scrubbing” of
excess carbon dioxide from the LM environment.
Lithium hydroxide canisters were used in Apollo 13 to scrub carbon dioxide. Since there were not enough lithium
hydroxide canisters in the LM to do the job, they needed to use the canisters from the CM as well. However, the CM
canisters were not designed to be used in the LM.
Mission Control came up with a solution for the astronauts. They attached the CM canisters to the LM system with an
improvised arrangement they called “the mailbox.” The mailbox worked and the Apollo 13 astronauts were able to return
safely to Earth.
Chemical Reaction
In a scrubber canister, lithium hydroxide reacts with carbon dioxide in a multi-step process forming lithium carbonate and
water as the final products.
1. Use the space below to write the balanced chemical equation for scrubbers used in Apollo 13.
2. Use the balanced chemical equation to solve the five challenges on the next page.
References
NASA. (Photographer). (1970, April 29). Apollo 13 Prime Crew [Web Photo]. Retrieved from
http://commons.wikimedia.org/wiki/File:Apollo_13_Prime_Crew.jpg
Lovell, J. NASA, (1975). Apollo expeditions to the moon. Retrieved from website: http://history.nasa.gov/SP350/editor.html
©2012, TESCCC
05/08/13
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Chemistry
HS/Science
Unit: 08 Lesson: 01
The Mathematics of the Carbon Dioxide Scrubber
Challenge One
A major challenge in keeping the Apollo 13 crew alive during their return to Earth was that the Lunar Module was only
equipped for two people for two days, but had to sustain three people for four days. The lithium hydroxide canisters from
the LM's carbon dioxide scrubbers would not last for all four days. Although you don’t have to rely on the scrubbers to
keep you alive, how much lithium hydroxide would be required to remove 75.0 grams of carbon dioxide from the
environment if all you had to be concerned about is the carbon dioxide? Use dimensional analysis.
Challenge Two
The CM had a supply of replacement lithium hydroxide canisters, but they were shaped differently and would not fit the
LM's container. An adapter then had to be created from materials within the craft itself. The astronauts named the adapter
the "mailbox." How much carbon dioxide could be removed if 3.0 kilograms of lithium hydroxide were used? Use
dimensional analysis.
Challenge Three
There was a great deal of water condensation in the Lunar Module on the return leg of the mission due to reduced
temperatures. There was worry that the condensation build up could damage the electronics of the LM by causing a short
circuit and possible fire. The reaction between lithium hydroxide and carbon dioxide produces water as a product. How
much water would be produced from the reaction of the 3.0 kilograms of lithium hydroxide with the excess carbon dioxide
in the LM? Use dimensional analysis.
Challenge Four
The Apollo 13 mission was determined to be a “successful failure”. Although the astronauts did not land on the Moon, they
were successfully brought home. A thorough investigation of the explosion, based on records of manufacturing processes
and maintenance logs, tracked the failure of the oxygen tank to multiple faults. None of the problems, had they occurred
alone, would have been critical, but together they led to a near disaster for the crew of Apollo 13. How much carbon
dioxide would have been removed from the breathing environment if the scrubber reaction produced 50.0 kilograms of
lithium carbonate? Use dimensional analysis.
Challenge Five
Using the information provided on carbon dioxide scrubbers, design a group challenge using the chemical reaction for
carbon dioxide scrubbers. Write the problem so that another group will be interested in the problem, understand the
chemical question, and be able to provide an answer to the challenge with the information in the question. Exchange
challenges and complete the calculations for the other group challenges in the class.
©2012, TESCCC
05/08/13
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