PASCO TD-8565 Adiabatic Gas Law Apparatus - Manual (Page 15)

Experiment 3B: Work Done by an Adiabatic Process
© 2009 Physics Enterprises 15
D. Number of mol, n.
Calculate the volume of air (in cm 3 ) at the initial 10 cm height when the stopcock was
open to the atmosphere using
V
0
= π r 2 h
0
= _________ (cm 3 )
where r is half the diameter displayed on the label of the Adiabatic Gas Law Apparatus.
Calculate the number of mol of gas from Eq. (1.3), with the density of air at STP of ρ =
0.00129 g/cm
3 , the volume V
0
, and the molecular weight of air M
air
= (0.8*28+0.2*32) g/
mol (assuming 80% nitrogen and 20% oxygen).
Compute the change in internal energy of the air,
Compare the change in internal energy with the area under the P vs. V curve.
Compare the area under the curve with the prediction of Eq. 3.6b.
air
air
M
V
n
0
ρ
=
= Δ = Δ
T nR U
2
5
= __________ mol
____________ J