Posted by Mike on .
Determine the density of methane (CH4) in g/L at 27.8oC and 1.1 atm.

Chemistry 
DrBob222,
The general gas formula of PV = nRT can be modified to
P*molar mass = density*R*T 
Chemistry 
Mike,
So I have gotten 2 different answers. I used V=nRT/P to get the volume. Which was 24.7. Then I used D=M/V and divided 16.042/24.7 to get .65g/L
Is that right? 
Chemistry 
DrBob222,
no. If you obtained two different answers why did you pick that one? You know something must be wrong. How did you get V = 24.7 L. If I plug those numbers into V =nRT/P I don't get that. But I do obtain a number that agrees with the formula I gave you.

Chemistry 
Mike,
V=nRT/P I used (1)(.0821)(300.8)/1=24.7

Chemistry 
DrBob222,
Two points.
If T is to 4 places I would use R as 0.08205 although that won't make much difference.
The other one makes more difference. P is 1.1 atm in the problem and not 1. 
Chemistry 
Mike,
Yes, thank you for catching that. So with the corrections (except I kept R as .0821) I got (1)(.0821)(300.8)/1.1=22.45. Then 16.042/22.45=0.71g/L
Is it now correct? I appreciate all your help!!! 
Chemistry 
DrBob222,
Yes. If that 1.1 is 1.1 and not 1.10 atm, then 0.71 is right. If it is 1.10 you should have one more place in your answer.

Chemistry 
Mike,
THANK YOU!!!