LiOH and NaOH can each react with CO2

Question

to form the metal carbonate and H2O.
These reactions can be used to remove CO2
from the air in a spacecraft.
a. Write a balanced equation for each
reaction.
b.In order to remove 214.3 g CO2 from the air, what mass of NaOH would be consumed? What mass of LiOH would be required to remove the same amount of CO2?
c. Based on your calculations, explain why LiOH is used during space missions rather than NaOH even though LiOH can cost up to 20x more than the NaOH per gram. Hint: SpaceX is hoping to get the cost of launching material to space down to “only” $1000/pound.

Answer 1

a. 2LiOH + CO2 ==> Li2CO3 + H2O
2NaOH + CO2 --> Na2CO3 + H2O

b. mols CO2 = grams/molar mass = 214.3/44 = 4.87
Convert to mols NaOH. 4.87 mols CO2 x (2 mols NaOH/1 mol CO2) = 9.74 mols NaOH needed. mass NaOH = mols NaOH x molar mass NaOH 9.74 x 40 = about 390 g but that's an estimate. You do it more accurately.
Same process for LiOH. Mols is same so 9.74 x 23.9 = estimate 233 g.
c. mols needed is same for LiOH and NaOH but the molar mass is so much lower for LiOH than NaOH that it requires much less LiOH than NaOH to remove the same amount of CO2. That weight difference means saving a lot of fuel to transport and launch the rocket.