A compound with empirical formula AB2, has the vapour density equal to it's empirical formula weight. Find it's molecular formula.
Empirical formula = AB2
Empirical formula weight = V.D.
Molecular weight = 2 x V.D.
n=Molecular weightEmpirical formula weightn=2 x V.D.V.D.n=2\text{n} = \dfrac{\text{Molecular weight}}{\text{Empirical formula weight}} \\[0.5em] \text{n} = \dfrac{\text{2 x V.D.}}{\text{V.D.}} \\[0.5em] \text{n} = 2n=Empirical formula weightMolecular weightn=V.D.2 x V.D.n=2
∴ Molecular formula = n[E.F.] = 2[AB2] = A2B4
