Question

Whitney's lung capacity was measured as 3.3 l at a body temperature of 37 ∘c and a pressure of 746 mmhg . how many moles of oxygen is in her lungs if air contains 21% oxygen?

Answer 1

the ideal gas equation is PV=nRT  
 where P=pressure  
 V=Volume  
 n=no. of moles  
 R=universal gas constant  
 T=temperature  
 The universal gas constant (R) is 0.0821 L*atm/mol*K    
 a pressure of 746 mmhg =0.98 atm= 1 atm (approx)   
 T=37 degrees Celsius =37+273=310 K (convert it to Kelvin by adding 273)    
 V=0.7 L (only getting oxygen, get 21% of 3.3L)    
 Solution:  
 (1 atm)(0.7 L)=n(0.0821 L*atm/mol*K)(310 K)  
 0.7 L*atm=n(25.451 L*atm/mol)  
 n=0.0275 mole   
 Answer:   
n=0.0275 mole of oxygen in the lungs.