A compound contains 'N' and 'O' atom. The ratio of mass percentage of 'N' and 'O' is 7:16. If the vapour density of compound is 46, then find the no of 'O' atoms present per molecule of the compound.

Answer 1

%N/%O = 7/16 but 7/16 is the same as 14/32 and that means the empirical formula is NO2.
vapor density = 46 = mm gas/mm H2 = mmgas/2 so mm gas = 92 (where mm = molar mass)
empirical formula x some # = molecular formula = 96 so the unit # must be 2.
(NO2)2 or N2O4 must be the molecular formula.