In a room at 24.5 degrees Celsius a balloon is filled with helium to a pressure of 768.0 mmHg. What is the density?

1 Answer
Mar 3, 2018

Well, we want the expression rho_"density"="mass"/"volume"

Explanation:

And we gots PV=nRT="mass"/"molar mass"xxRT..

And thus Pxx"molar mass"=("mass"xxRT)/V

And so rho="mass"/V=(Pxx"molar mass")/(RT)

And thus....rho=((768*mm*Hg)/(760*mm*Hg*atm^-1)xx4.003*g*mol^-1)/(0.0821*(L*atm)/(K*mol)xx297.7*K)

=0.166*g*L^-1...and answer with units of density as required.

Will this balloon float?