Question

The empirical formula of a compound is `CH_(2)O`. If its vapour density is 90, find out the molecular formula of the compound.

Answer 1

Empirical formula=`CH_(2)O`
Empirical formula weight = `= 12 + (1xx2) + 16 = 30`
Vapour density (VD) = 90
Molecular wieght =`VD xx 2 = 180`
Molecular formula = `("empirical formula")_(n)`
`n=("Molecular weight")/("Empirical formula weight")=180/30 = 6`
Thus, molecular formula = `(CH_(2)O)_(6) = C_(6)H_(12)O_(6)`
In stoichiometry, we find out the quantitative relationship between the reactants and the products on the basis of balanced chemical equation.