empirical formula is the simplest ratio of whole numbers of components in a compound.
the empirical formula - C₃H₅
mass of empirical formula - (12 g/mol x 3) + (1 g/mol x 5) = 41 g
we have to find how many empirical units make up the molecular formula
number of empirical units = molecular mass / mass of empirical formula
empirical units = 205.4 g/mol / 41 g = 5.00
molecular formula - n (C₃H₅)
n - number of empirical units
therefore n = 5