To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 3.5-L bulb, then filled it with the gas at 1.40 atm and 30.0 ∘C and weighed it again. The difference in mass was 5.5 g . What is the gas?

1 Answer
anor277
Jan 15, 2018

We gots #"dinitrogen"...."or carbon monoxide"....#

Explanation:

Well, we use the old Ideal Gas equation....

#PV=nRT="mass"/"molar mass"*RT#..

And so #"molar mass"=("mass"*RT)/(PV)#

...and we fill in the values....

#"molar mass"=(5.50*gxx0.0821*cancel(L*atm)/(cancelK*mol)*303.15*cancelK)/(1.40*cancel(atm)xx3.5*cancelL)#

#=27.9*g*mol^-1#

...and this mass is consistent with dinitrogen. Note that carbon monoxide would be a possibility, but for the fact that this is a HETEROATOMIC molecule.....

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