posted by CM on .
An adult takes about 15 breaths per minute, with each breath having a volume of 500mL. if the air that is inhaled is "dry", but he exhaled air is 1 atm pressure is saturated with water vapor at 37 degree C(body temp), what mass of water is lost from the body in 1hr? The vapor pressure of water at 37degree C is 47.1 mmHg.
I tried doing this with partial pressures but its not coming out right.Please Help!!
The volume of air inhaled in 1 hour is
(60 min/hr)(15 br./min) = 900 breaths
(900 br.)(0.500L/breath) = 450 L
To find moles of H2O, use the Ideal Gas Law:
PV = nRT
1 atm = 760 mm Hg
47.1mmHg/760 mmHg/atm = 0.061974 atm
P = 0.061974 atm for water vapor
R = 0.08206 L.atm/K.mol
T = 273 + 37 = 310K
Find moles of H2O:
n = PV / RT
Mass of H2O in grams is:
(moles H2O)(18.015 g/mol.H2O)
but the air that came out has a pressure of 1atm. doesnt that mean it has the partial pressure of air and water in it??
the question was
....but the exhaled air at 1atm pressure is saturated with water vapor.....