An unknown compound with a molar mass of 155.06 g/mol consists of 46.47% c, 7.80% h, and 45.72% cl. find the molecular formula for the compound.

The empirical formula should be first determined. Empirical formula is the simplest ratio of whole numbers of components in a compound.
for 100 g of the compound 
                                    C                                   H                             Cl
mass                       46.47 g                        7.80 g                          45.72 g
number of moles    46.47 g/12 g/mol       7.80 g/1 g/mol         45.72 g/35.5 g/mol
                                 = 3.87 mol                = 7.80 mol                = 1.29 mol
divide all by the least number of moles 
                                 3.87/1.29 = 3           7.80/1.29 = 6.04        1.29/1.29 = 1
when they are all rounded off to the nearest whole number 
number of atoms are as follows
C - 3
H - 6
Cl - 1
the empirical formula is C₃H₆Cl
molecular formula is the actual number of components in the compound 
molar mass  = 155.06 g/mol 
we have to find the mass of the empirical unit 
mass of C₃H₆Cl - (12 g/mol x 3) + (1 g/mol x 6) + (35.5 g/mol x 1) = 77.5 
we have to then find how many empirical units are in the molecular formula 
number of units = molecular mass / empirical unit mass
                          = 155.06 g/mol / 77.5 = 2.00
there are 2 empirical units 
molecular formula = 2 (C₃H₆Cl) 

molecular formula - C₆H₁₂Cl₂

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