Question

50ml of each gas A and B takes 150and 200 seconds respectively for effusing through a pin hole under the similar condition. if molecular mass of gas B is 36,what will be the molecular mass of another gas?

Answer 1

rate of effusion of gas A/rate of effusion of gas B=
$\sqrt{ \frac{molecular \: weight \: of \: b}{molecular \: weight \: of \: a \: } }$
=> (50/150)/(50/200) =
$\sqrt{ \frac{36}{molecular \: weight \: of \: a } }$
=> molecular weight of a be x.
4/3=√36/x => on squaring on both sides,
${ (\frac{4}{3}) }^{2} = \frac{36}{x}$
=> 16/9= 36/x => x=36(9/16)= 20.50 grams.
Molecular weight of another gas B=20.50 grams .
Hope it helps you...