Part A
How long does it take a person at rest to breathe one mole ofair if the person breathes 84.0 mL/s of air that is measured at 25∘C and 755 mmHg? Express your answer numerically in seconds.
Part B
Typically, when a person coughs, he or she first inhales about2.50 L of air at 1.00 atm and 25 ∘C. The epiglottis and the vocalcords then shut, trapping the air in the lungs, where it is warmedto 37 ∘C and compressed to a volume of about 1.70L by the action ofthe diaphragm and chest muscles. The sudden opening of theepiglottis and vocal cords releases this air explosively. Justprior to this release, what is the approximate pressure of the gasinside the lungs?
Express your answer numerically in atmospheres.
Part C
Helium-oxygen mixtures are used by divers to avoid the bends andare used in medicine to treat some respiratory ailments. Whatpercent (by moles) of He is present in a helium-oxygen mixturehaving a density of 0.508 g/L at 25 ∘C and 721 mmHg?
Express your answer numerically as a percentage.
