I have the first two parts answered but I don\'t know how to do the last part pl
ID: 2172066 • Letter: I
Question
I have the first two parts answered but I don't know how to do the last part please help! Human lung capacity varies from about 4.0L to 6.0L, so we shall use an average of 5.0L. The air enters at the ambient temperature of the atmosphere and must be heated to internal body temperature at an approximately constant pressure of 1.00 atm in our model. Suppose you are outside on a winter day when the temperature is -2.00F.Part A How many moles of air does your lung hold if the 5.0 L is at the internal body temperature of 37 C?
n = .196 mol
Part B How much heat must your body have supplied to get the 5.0 L of air up to internal body temperature, assuming that the atmosphere is all N2?
Q = 320 J
Part C
Suppose instead that you manage to inhale the full 5.0 L of air in one breath and hold it in your lungs without expanding (or contracting) them. How much heat would your body have had to supply in that case to raise the air up to internal body temperature?
Q = _____ J
Explanation / Answer
I redid your answers for 1st 2 parts & thery are fine.
in the 2nd part u had assumed the prcoess occuring at const pressure i.e 1 atm. This inherently involves volume changes i.e. expansion/contraction of lungs
and so you used Cp for heat calculation. (Cp = 29.1)
(0.196 mols )* (29.1)*(37 - (-18.9)) = 319 320 J
IN 3rd case, the volume of lungs is constant . So Cv is used [ Cp - Cv = R ]
(0.196)*(29.1 - 8.314 )*(37 - (-18.9)) = 227.74 J (ans)
hope this helps