Ideal Gas law [Archive] - Physics Forums

ElectricMile

Feb17-05, 02:14 PM

Consider a high pressure gas cylinder of methane which exhibits a pressure of 200 atmosphers (absolute) at a temp. of 0*C in a small storage building. the building catches fire whcih causes the temp of the cylinder to rise to 1200*C. What would the pressure in the cylinder be then? express your answer in both atmopheres and in psi(lbf/in^2), assume methane behaves as an ideal gas.

ok. seems easy. but im confused about this whole ideal gas thing. do i always use (0.08205 atmos. liters/ mole K) for R?

if so then would i do...

(P1)(V)=(R)(T1) = (200)(V)=(0.08205)(273)
so, V = ((0.08205)(273))/(200) = 0.1119
but this number seems unlikley. but if so
(P2)(V)=(R)(T2) = (P2)(0.1119)=(0.08205)(1473)
so. P2 = 1080atm? am i doing this somewhat right?

vincentchan

Feb17-05, 02:36 PM

you don't need to evaluate the volume in this problem, since you don't have the molar number.
PV=nRT implies P/T=nR/V
whereas the right hand side is constant... therefore, you have
P_{i}/T_{i}=P_{f}/T_{f}