In: Chemistry
Part A
How long does it take a person at rest to breathe one mole of air 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 about 2.50 L of air at 1.00 atm and 25 ∘C. The epiglottis and the vocal cords then shut, trapping the air in the lungs, where it is warmed to 37 ∘C and compressed to a volume of about 1.70L by the action of the diaphragm and chest muscles. The sudden opening of the epiglottis and vocal cords releases this air explosively. Just prior to this release, what is the approximate pressure of the gas inside the lungs?
Express your answer numerically in atmospheres.
Part C
Helium-oxygen mixtures are used by divers to avoid the bends and are used in medicine to treat some respiratory ailments. What percent (by moles) of He is present in a helium-oxygen mixture having a density of 0.508 g/L at 25 ∘C and 721 mmHg?
Express your answer numerically as a percentage.