Question

An unknown compound has the empirical formula CH2O and a molecular mass of 180 amu. What is the molecular formula of the compound

Answer 1

The empirical formula gives the simplest ratio of whole numbers of components in the compound. Molecular formula gives the actual composition of elements in the compound.
empirical formula - CH₂O
Mass of one empirical unit = 12 + (1x2) + 16 = 30 a.m.u
We have to next calculate how many empirical units make up the molecular formula. For that we have to divide molecular mass by mass of one empirical unit.
Number of empirical units = 180 a.m.u / 30 = 6
There are 6 empirical units 
Therefore molecular formula = 6 x(CH₂O) = C₆H₁₂O₆
Molecular formula = C₆H₁₂O₆