The carbon dioxide generated by the personnel in submarines and spacecraft must be removed from the air and the oxygen recovered. Submarine design teams have investigated the use of potassium superoxide, KO₂, as an air purifier because it reacts with carbon dioxide and releases oxygen (FIG. 3C.3):

Calculate the mass of KO₂ needed to react with 50. L of carbon dioxide at 25°C and 1.0 atm.

ANTICIPATE A volume of 50 L under normal conditions corresponds to about 2 mol CO₂, and the stoichiometry of the equation indicates that about 4 mol KO₂ would be needed. Because the molar mass of KO₂ is about 70 g · mol^–1, you should suspect that the answer will be close to 280 g.

PLAN Convert from the given volume of gas into amount of CO₂ molecules (by using the molar volume), then into the amount of KO₂ formula units (by using a mole ratio), and then into the mass of KO₂ (by using its molar mass). If the molar volume at the stated conditions is not available, then calculate the amount of gas molecules from the ideal gas law: n = PV/RT.

Transcribed Image Text:

4 KO₂ (s) + 2 CO₂(g) 2 K₂CO3(s) + 3 O₂(g)