CHEMISTRY Question

Question

 In a space shuttle, the CO₂ that the crew exhales is removed from the air by a reaction within canisters of lithium hydroxide. Let's assume that one astronaut exhales about 825.  L of CO₂ daily. What mass of water will be produced when this amount reacts with LiOH? The other product of the reaction is Li2CO3.  When answering this question include the following:

1. Have both the unbalanced and balanced chemical equations.
2. Explain how to find the molar mass of the compounds.
3. Explain how the balanced chemical equation is used to find the ratio of moles (hint: step 3 in the video).
4. Explain how many significant figures your answer needs to have.
5. The numerical answer

Answer 1

-CO₂(g) + LiOH(s) ==> Li₂CO₃(s) + H₂O(g) ... unbalanced equation

-CO₂(g) + 2LiOH(s) ==> Li₂CO₃(s) + H₂O(g) ... balanced equation

-molar mass of a compound is the sum of the atomic masses (in g) of each element making up the compound

-The balanced equation tells us that the mole ratio of LiOH to CO₂ is 2:1 and the mole ratio of LiOH to H₂O is also 2:1. The mole ratio of CO₂ to H₂O is 1:1 also. No idea what step 3 in the video is so can't comment.

-The answer should have 3 significant figures because the only data given in the problem is 825. L which has 3 sig.figs.

-The numerical answer is based on the mol ratio of CO₂ : H₂O which is 1:1. However, mols of CO₂ will depend on the pressure and temperature in the shuttle, which we don't know. If we assume STP (standard temperature and pressure), the 1 mol of CO₂ = 22.4 L and we can find moles and grams of H₂O.

825 L CO₂ x 1 mol / 22.4 L x 1 mol H₂O / mol CO₂ = 36.83 mols H₂O

36.83 mols H₂O x 18.0 g H₂O/ mol = 662.9 g H₂O = 663 g H₂O (3 sig.figs.)