Help with molar mass of a gas

[From: ] [author: ] [Date: 12-07-02] [Hit: ]

197) =(.286) X (.0821) X (288) /( Molecular weight) or Z NOWsolves for the molecular weight. so you multiply both side by the molecular weight or in this case (Z ) use Z as a variable.(.642) X (.......

R= (constant) 0.0821
T= 288 remember to always use Kelvin, if it is in Celcius switch it using K= C + 273.

(.642) X (.197) = (.286) X (.0821) X (288) / ( Molecular weight) or Z

NOW solves for the molecular weight. so you multiply both side by the molecular weight or in this case ( "Z" ) use Z as a variable.

(.642) X (.197) X "Z" = (.286) X (.0821) X (288)

now multiply the .642 times the .197. and multiply the 3 things on the right. now just solve for Z. and divide the right side by the left

0.126474(Z) =6.7624128

divide to solve for Z

Z = 6.76 DIVIDED BY .126
Z = 53.7
Z= molecular weight

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start with these 2 equations...
PV = nRT
n = mass / mw

substitute and rearrange..
PV = (mass / mw) x RT
mw = mass x RT/(PV)

solve...
mw = (0.286g) x (0.08206 Latm/molK) x (288K) / ((0.642atm) x (0.197L))
mw = 53.4 g/mol

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questions?

12

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