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 the exhaled air at 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.

How many moles of water per breath?

n=PV/RT

P=vaporpressure V is volume of breath
T is temp.

Now, knowing moles per breath, convert that to one hour. Finally convert moles water to grams water.

thanks so much!! i thought it had something to do with partial pressures.

I am irked. GK gave you a correct answer 20 min ago, and you posted again. Besides being rude, it wastes volunteers time. Please don't do that again.

actually, it does. You have to use the partial pressure of water in the equation, just as I said, and as GK said.

Your question has already been answered here:

http://Jiskha.com/display.cgi?id=1224463048

The moles of a gas in a mixture, in this case water vapor,depends on the partial pressure of that gas independently of any other gases present. That comes out of Dalton's Law of Partial Pressures. I gave you a complete procedure on how to calculate the moles of H2O vapor. The moles can be easily converted to grams. Do multiple postings of the same question will not get you a more detailed answer.

sorry about that,i am just so busy.i am a really good student at chem,just had a really big doubt.the question was confusing and i thought mayb GK mistook it as well. but it wont happen again

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