What mass of Ba(OH)2 would handle the CO2 exhaled by the three astronauts during their eight-day mission? How does this mass compare to LiOH?

Question

On spaceships, it is important to use lightweight, non-bulky materials. The engineers chose LiOH over Ba(OH)2. What mass of Ba(OH)2 would handle the CO2 exhaled by the three astronauts during their eight-day mission? How does this mass compare to LiOH?

Answer 1

For LiOH:

3 men x 18.2 mol CO₂/men/day x 8 days = 436.8 total mols CO₂ exhaled

2LiOH + CO₂ ==> Li₂CO₃ + H₂O ... balanced equation for scrubbing CO₂ with LiOH

436.8 mols CO₂ x 2 mol LiOH / mol CO₂ x 23.95 g / mol = 20,923 g = 20.9 kg LiOH (3 sig. figs.)

For Ba(OH)₂:

3 men x 18.2 mol CO₂/men/day x 8 days = 436.8 total mols CO₂ exhaled

Ba(OH)₂ + CO₂ ==> BaCO₃ + H₂O ... balanced equation for scrubbing CO₂ with Ba(OH)₂

436.8 mols CO2 x 1 mol Ba(OH)2 / mol CO2 x 171 g / mol = 74,693 g = 74.7 kg Ba(OH)₂ (3 sig. figs.)

Thus, the mass of Ba(OH)₂ required would be about 3.5 times that of LiOH.