Question

If same moles of O2 diffuse in 18 sec and same mole of other gas diffuse in 45 sec then what is the molecular weight of the unknown gas?

Answer 1

diffisuion factor is directly proporsional to molecular weight of a gas
which helps us establish
(mwt. of O2) is directly proportional to (18secs)
which gets us to...
36*k=18 ....(k is constant of propartionality)
and thus k=1/2,
now in the unknown gas,
molecular weight*1/2=time
solving it gets us to molecular wt.=90