Humans need to breath a mixture of gases at an appropriate pressure and temperat

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Humans need to breath a mixture of gases at an appropriate pressure and temperature, e.g., 1 bar & 298 K. Let us approximate the ideal mixture as 78.7% nitrogen, 21% oxygen, and 0.3% carbon dioxide. There are 6 astronauts on a space station, each of whom breathes in an average of 0.5 L per breath and takes about 15 breaths per minute. To keep the air breathable, some of it is removed, scrubbed (doesn’t change its composition) and returned, while some of it is purged (released) into space. What are the required net rates (kg/min) of 1) input of pure oxygen into the space station (ans = 0.2 kg/min), 2) input of pure nitrogen into the space station (ans = 0.65 kg/min), and 3) purge (ans = 0.86 kg/min) from the station to keep the station with an ideal mixture of gases at steady-state? The composition of exhaled air is 78.7% nitrogen, 16% oxygen, and 5.3% carbon dioxide (plus the rest). Composition is given as a mole percentage. Assume ideal gas and no mass loss during breathing (this isn’t technically true, you lose about 0.2 kg of carbon per ~17,000 breaths). Comment on how good of a setup you this would be to take care of the astronauts. Can you think of an alternative?

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