Question # A resting adult requires about 240-mL of pure oxygen/min andbreathes about 12 times every minute. If inhaled air contains 21percent oxygen by volume a

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ANSWERED A resting adult requires about 240-mL of pure oxygen/min andbreathes about 12 times every minute. If inhaled air contains 21percent oxygen by volume and exhaled air is 16 percent oxygen byvolume, what is the volume of air per breath? (Assume that thevolume of inhaled air is equal to that of exhaled air) Comments 2020-11-21
1. A resting adult requires about240-mL of pure oxygen/min and breathes about 12 times every minute.If inhaled air contains 21 percent oxygen by volume and exhaled airis 16 percent oxygen by volume, what is the volume of air perbreath? (Assume that the volume of inhaled air is equal to that ofexhaled air) oxygen reqd.= 240 ml/mt.
no.of breaths = 12/mt
oxygen reqd./breath $$\displaystyle={\frac{{{240}}}{{{12}}}}$$ = 20 ml.
oxygen in inhaled air = 21% $$\displaystyle={\frac{{{21}}}{{{100}}}}={0.21}$$
hence air reqd. to inhale $$\displaystyle={\frac{{{20}}}{{{0.21}}}}={\frac{{{2000}}}{{{21}}}}$$
air exhaled = air inhaled $$\displaystyle={\frac{{{2000}}}{{{21}}}}$$
oxygen in exhaled air = 16%=0.16
oxygen in exhaled air $$\displaystyle={\frac{{{2000}\times{0.16}}}{{{21}}}}={15.24}$$
2. $$\displaystyle{\frac{{{240}}}{{{12}}}}={20}{m}{L}$$
of oxygen/min
20mL=.37x
20mL = .37x (x=total volume per breath)
x=54.05
54.05-34mL=34.05mL
Because there is only 2 sig fig the answer is34mL volume air per breath.
I think thats right.